Symmetrical multipath method for determining the distance between two transceivers

TECHNOLOGICAL BACKGROUND OR INVENTION

1. Field of the Invention.

0001The invention relates to a method for determining the spatial distance between two wirelessly communicating transceivers from one another within a range of the order of 10 km. Furthermore, the invention relates to a system of at least two wirelessly communicating transceivers, which is designed to determine the spatial distance of the transceivers from one another within a range of the order of 10 km. Finally, the invention relates to a transceiver for performing the method mentioned.

2nd State of the art

0002Three different media are used to measure the distance of mobile and stationary objects: radio, infrared and ultrasound. Mainly the so-called pulse transit time driving is used. The transit time of transmitted pulses is determined by measuring the time of arrival (TOA) and comparing it with the start time of the pulses. With the known propagation speed in the medium, the distance is then calculated from the pulse transit time, which is also referred to in the context of this application as the signal transit time.

0003Another method for distance measurement measures the signal strength (Receive Signal Strength = RSS) of received pulses and uses this to estimate the distance. The signal strength is strongly influenced by interference, attenuation and reflections. Experience has shown that this method is too imprecise and unreliable for the distance measurement.

0004Another method with which the distance can also be calculated is the position determination by means of angle determination (angel of arrival = AOA) and triangulation. However, determining the distance of an object requires two cooperating devices with a known distance from one another. The angle measurement is relatively complex (special antennas, time expenditure) and imprecise due to interference, attenuation and reflections. If there is no line of sight, the angle measurement is severely restricted or no longer possible, depending on the medium used. Experience has shown that this method is too imprecise and unreliable for the distance measurement.

0005Infrared and ultrasound methods based on the pulse transit time method also have a considerable number of disadvantages. The range of the systems is not very large, common environmental influences such as daylight, sound sources or reflections disturb them strongly and signal attenuations such. B. by heavy smoke or haze already lead to the failure of these systems. Because of the disadvantages mentioned, these methods are not suitable for precise and reliable distance measurement

0006Pulse delay methods based on radio signals (English radio communication signals) are less sensitive to environmental disturbances and experience has shown that they are most accurate.

0007Classic radar systems are considered to be disadvantageous in terms of effort, interference immunity and the clear identification of objects. The reliability and accuracy strongly depend on the reflection properties of the object to be measured and the propagation conditions of the radar waves. In addition to the pulse transit time method, the angle determination method is used, which has the disadvantages already mentioned. The transmission of any data is not possible with the classic radar systems.

0008Widely used systems that use the distance measurement according to the pulse transit time method to determine the position are the satellite-based positioning systems. This includes, for example, the positioning system known as the Global Positioning System (GPS). The satellite-based systems have a number of disadvantages. The construction and operation of the infrastructure is very complex and expensive. With a reduced line of sight to the satellites, availability is greatly reduced due to weakening (e.g. narrow gorges, forest) and no longer provided due to shadowing (e.g. in buildings). In addition, only the own position determination is possible, but not the position determination of distant objects. In order to determine the distance to a distant object, an additional system for message transmission is required, since this is not possible via the satellites. Distance measurement is only possible by a second position determination and exchange of position data. The accuracy is also assessed as insufficiently accurate, since the errors of two position determinations in the distance calculation (1-3 m for differential GPS) can add up. Furthermore, the devices for position determination are characterized by measurement times that are too long of up to several minutes, which makes the distance determination of mobile objects too imprecise or no longer possible. As already mentioned, transmission of any data via the satellite-based systems is not possible. There is also a dependency on the operator, who can limit the accuracy and availability and may charge fees for use.

0009Another possibility of distance measurement is the position determination of mobile radio subscribers with the help of mobile devices, e.g. 8. Mobile phones for operation according to the GSM standard. However, the attainable accuracy of the position determination of at best 60 m is assessed as very disadvantageous. Here, too, there is a dependency on the operator, who charges fees for the use.

0010In other known methods and systems that measure the round trip time of a sequence of radio pulses between two transceivers (active pulse radar, see e.g. <patcit id="pcit0001" dnum="US6483454B1"><text>US 6,483,454 B1</text></patcit>), there are a number of disadvantages. In the known round-trip time methods according to the TOA principle (Time of Arrival), also called two-way method, there is a very large dependence of the accuracy of the position determination on the accuracy of the clock generators for time measurement. When data is transmitted at the same time, the pure pulse transit time in the medium results in relatively long round-trip intervals, which are caused by the transmission time of the data frames. A typical ratio is 1: 10,000. Very precise clock generators with an accuracy of better than ± 1 ppm and therefore cost-intensive components are necessary to achieve high accuracy. If inexpensive clock generators (± 50 ppm) were used, insufficient accuracy (approx. 10 m) could be achieved.

0011For this reason, the increase in accuracy is also achieved by shortening the round trip intervals. However, this has the consequence that less or no additional data can be transmitted and special message protocols have to be used. Standardized message protocols cannot be used, which is another major disadvantage of these methods with regard to the reusability or extensibility of standards.

0012The accuracy that can be achieved in the known methods also depends on the smallest unit of time measurement. To increase the accuracy, very small time units are used, which makes it necessary to use very fast clock generators and time counters (30 cm distance corresponds to 1 ns time unit or 1 GHz clock frequency). However, such faster time counters are considered to be very disadvantageous, since this goes hand in hand with an increase in energy consumption and the cost of implementation.

0013<patcit id="pcit0002" dnum="US2001053174A1"><text>US 2001/053174 A1</text></patcit> describes a method for determining distances in the range up to 1000 m, in which bits are exchanged between two transmitter receivers in two reciprocal round trips. A distance between the two transceivers is determined on the basis of transmission, reception, response and round-trip times.

SUMMARY OF THE INVENTION

0014The object of the invention is to provide a method for determining the distance, which is distinguished within a range of the order of 10 km by an increased accuracy of the distance measurement in comparison with known methods and at the same time the use of conventional quartz clock generators with an error of up to ± 50 ppm allows

0015Another object of the invention is to provide a method for determining the distance that is distinguished within a range of the order of 10 km by an increased accuracy of the distance measurement compared to known methods and thereby the use of clock generators with comparatively low frequencies in the range of approximately 100 MHz for time measurement in the transmitter receivers involved.

0016Another object of the invention is to provide a method for determining the distance which is characterized within a range of the order of 10 km by an increased accuracy of the distance measurement in comparison with known methods and at the same time generates a low energy requirement on the part of the transceivers involved.

0017A further object of the invention is to provide a method for determining the distance which is distinguished within a range of the order of 10 km by an increased accuracy of the distance measurement in comparison with known methods and at the same time enables the transceivers required to carry out the method to be produced cost-effectively

0018Another object of the invention is to provide a method for determining the distance that can be used in conjunction with known, standardized message protocols such as Bluetooth, WLAN or ZigBee without the data link layer of these protocols being modified (layer 2 according to the ISO / OSI reference model) must become.

0019According to a first aspect of the invention, a method for determining the spatial distance between two wirelessly communicating transceivers from one another is provided within a range of the order of 10 km. In the method of the invention, both transceivers each initiate at least one signal round trip, a signal round trip comprising the steps described below:<ol id="ol0001" compact="compact" ol-style=""><li>a) sending at least one request data frame, which contains a sequence of at least two signal pulses with a predetermined pulse time interval, from a first transmitter receiver initiating the signal rounding to a second transmitter receiver at a request transmission time,</li><li>b) receiving the request data frame at the second transceiver at a request reception time,</li><li>c) Sending a response data frame, which contains a sequence of at least two signal pulses with a predetermined pulse interval, from the second transceiver to the first transceiver at a response transmission time, which has a respective response time interval from the request reception time, and detection (Engl: Detect) of the respective response time interval ,</li><li>d) receiving the response data frame at the first transceiver initiating the signal round and detecting a response reception time associated with the reception of the response data frame relative to the request transmission time,</li></ol>

0020Furthermore, the method according to the invention comprises an evaluation with the steps:<ul id="ul0001" list-style="none" compact="compact"><li>e) Ascertaining a round trip time interval between the respective request transmission time and the respective response reception time for each signal round trip, this step being able to be carried out at any time after the relevant signal round trip,</li><li>f) determining a signal transit time between the two transceivers on the basis of the determined round time intervals and the response time intervals and</li><li>g) determining the spatial distance between the first and second transceivers by multiplying the signal transit time by a known propagation speed of the signal pulses.</li></ul>

0021In the method according to the invention, the signal round trips are carried out in such a way that the response time intervals are either identical or have a difference, in the case of carrying out more than one signal round trip initiated by each transceiver, the difference being a maximum of 200 microseconds.

0022The method according to the invention is distinguished on the one hand by its property as a symmetrical multi-way method. Two aspects of symmetry interact advantageously in a previously unknown way. A first aspect of symmetry of the method according to the invention is the combination of a first signal round, in which the first transceiver is the starting and destination point, with a second signal round, which has the second transceiver as starting and target point. The two transceivers can also initiate several signal rounds. The symmetrical multi-way method according to the invention makes the distance determination considerably less sensitive to fluctuations in the ambient temperature and the supply voltage than conventional methods for determining the distance. Furthermore, slight deviations in the performance parameters of circuits that are used in the transmitter receivers involved (so-called sample variations) do not significantly affect the accuracy of the distance determination.

0023The method according to the invention is also characterized by a second aspect of symmetry, in that the response time intervals in the first transceiver and in the second transceiver are either identical or have a difference, the amount of which is a maximum of 200 μs. A response time interval is the time difference between a time of reception of a request data frame and the transmission of a response data frame in response to the received request data frame at a transceiver. The response time interval depends on the processing time at the transceiver, for example in connection with checking the request data frame. Furthermore, the response time interval is determined by the length of a request data frame received and by protocol regulations, which can prescribe, for example, compliance with a minimum and a maximum response time interval. Fluctuations in the response time intervals are caused by circuit-related delays in the implementations of the transceivers.

0024Literally identical response time intervals are hardly possible from a technical point of view because the smallest deviations in the response time intervals can always be demonstrated with the corresponding measurement accuracy. In the context of this application, “identical” means the same values ​​of the response time intervals within the scope of the measurement accuracy, which is appropriate for a specific implementation. For example, in an implementation of the method according to the invention, only a relatively low accuracy of the location determination in the range of ± 2 m may be required. In such a case, a lower accuracy of the measurement accuracy is appropriate for a comparison of the response time intervals than with a required accuracy of ± 50 cm. Within the scope of such a reduced accuracy, response time intervals that have a slight difference with higher measurement accuracy can be assessed as identical. It should be noted that this explanation should only serve to interpret the term "identical". A comparison of response time intervals is not necessary when carrying out the method according to the invention. Such a comparison can serve to demonstrate the use of the method according to the invention. It is also conceivable that such a comparison is carried out within the scope of an exemplary embodiment.

0025With the method according to the invention, a distance determination at a distance of 10 km with an error caused by quartz tolerances of only ± 150 cm is made possible. Other sources of error are not taken into account in this specification

0026In a preferred embodiment, in which the difference in the response time intervals is a maximum of 20 microseconds, taking into account all error sources which, in addition to the error caused by quartz tolerances, can impair the accuracy of the method of the invention, one can in practice determine a distance of 10 km Accuracy of approx. ± 100 cm, for a distance of 1 km even ± 50 cm or better can be achieved.

0027For the surprisingly high accuracy of the method according to the invention achieved in relation to the simplicity of the required technical means, the combination of the feature of the signal round trips initiated by both transmitter receptions is identical to the feature or only within the framework of a difference of at most 200 μs (in the preferred exemplary embodiment at most 20 microseconds) Occurring response time intervals of very great importance, so far not recognized by experts. As will be explained in more detail below with the aid of error calculations and exemplary embodiments, this feature makes the error in the distance determination insensitive to conventional methods in relation to inaccuracies in the time measurement in the transceivers involved in the distance measurement. Relatively imprecise clock generators can therefore be used for time measurement without the accuracy of the distance determination being significantly reduced thereby. For example, commercially available, very inexpensive quartz crystals with a clock accuracy of ± 50 ppm and clock generators derived from quartz oscillator clocks with this accuracy are used without their errors causing a significant deterioration in accuracy. In this way, an accuracy of the distance determination that was previously not considered possible with such simple means is achieved

0028The method according to the invention enables a distance determination with the specified accuracy in a short time. A distance determination takes only about 2 ms.

0029The method according to the invention does not prescribe a fixed sequence between the first and the second signal round trip. In the method according to the invention, the steps of determining the respective round trip interval (steps e) and f)) can either be carried out immediately after the end of each signal round trip. Or it is waited until both signal rounds are completed before starting the evaluation in steps e) and f).

0030The method according to the invention is suitable for the simultaneous transmission of any data between mobile and stationary transceivers, in a data frame which at the same time contains the data for the distance measurement in the form of at least one signal pulse as a request data frame or response data frame.

0031The process does not require any additional infrastructure. It can also be used in buildings. With an estimated energy requirement of approximately 360 μJ per distance determination in the case of an implementation in an integrated circuit, another essential advantage of the invention is shown. Because of this low energy requirement, it is suitable for the use of battery-operated transmitter receivers with a long operating time.

0032The signal processing in the method according to the invention is particularly simple. Only basic arithmetic operations are used to determine the distance. The distance determination can therefore be carried out in a simple arithmetic unit or in a few clock cycles on a microprocessor. It is therefore available very quickly, especially immediately after the signal rounds have been carried out.

0033The method according to the invention is also suitable for high-precision and fast position determination, for speed measurement and for acceleration measurement, as will be explained in more detail below.

0034The method according to the invention can be used in communication networks. The use of suitable message protocols allows a very large number of stations in a limited space without endangering the reliability of the method according to the invention. The use of known message protocols enables the ability to carry out a distance determination on an ad-hoc basis without the need to previously negotiate process parameters.

0035Regulations of known standardized message protocols such as checksum calculation and encryption can further increase the reliability and security of the method according to the invention, as will be explained in more detail below.

0036The method according to the invention can, by combining a plurality of distance measurements according to the invention between more than two transceivers via one or more intermediate stations to distant stations, make it possible to determine the distance even over great distances with high precision.

0037The method according to the invention can be used wherever knowledge of a distance or a position or a change in position of people, animals or stationary and mobile objects is required. It can be used, for example, in the area of ​​wireless data transmission networks, building automation, industrial automation, material and goods logistics, vehicle and person navigation, or local and remote sensing. Further application examples are mentioned in the description of preferred exemplary embodiments.

0038In addition to the term round-trip interval, the term “round-trip time” is also used with the same meaning in the context of this application. In addition to the term response time interval, the term response time with the same meaning is also used. It is essential that these are not time points, but time differences. The round trip time interval is the duration of a signal round trip, that is the time interval (the time difference) between a request transmission time and a response reception time within a signal round trip. The response time interval is the time difference between a request reception time and a response transmission time within a signal round trip.

0039Additional features of exemplary embodiments of the method according to the invention are described below. Exemplary embodiments of the method according to the invention are also specified in the claims. Unless otherwise to the contrary directly and unambiguously results from the description or the claims, the exemplary embodiments can also be implemented in combination with one another.

0040In a preferred exemplary embodiment, a signal round trip initiated by the second transmitter-receiver is carried out in each case after a signal round trip carried out by the first transmitter-receiver. It is essential that the second transceiver initiates a signal round after it has sent the response data frame to the first transceiver. It goes without saying that the designation "second" and "first" transceiver is interchangeable in this exemplary embodiment. This method provides no or only a slight temporal overlap of the signal round trips. A slight temporal overlap of the signal round trips can result from the second transmitter-receiver initiating a signal round-trip by sending out a corresponding second request data frame before the first transmitter-receiver has received first response data frames previously sent. Since a distance of 10 km corresponds to a signal transit time of 30 microseconds, such an overlap, however, does not significantly accelerate the method.

0041The method of this exemplary embodiment is also referred to in the context of this application as a double-sided two-way method. When performing multiple signal rounds, it is referred to as a multi-sided two-way process

0042In an alternative exemplary embodiment, the signal round trips initiated by the two transceivers are coupled to one another. The second transceiver initiates the transmission of a signal round trip at the same time, the response data frame which is assigned to a first signal round trip initiated by the first transceiver simultaneously forming the request data frame of a second signal round trip initiated by the second transceiver. In this exemplary embodiment, step c) of a signal round trip initiated by the first transmitter-receiver simultaneously forms step a) of a signal round trip initiated by the second transmitter-receiver. This procedure can be agreed as a standard feature, for example. It can also be identified by sending out a special, combined request and response data frame that is interpreted and treated accordingly on the recipient side. Such a data frame is always referred to in this application as a "combined request and response data frame" in order to avoid confusion with the abbreviation "request and response data frame" also used, which is to be understood as "request data frame and response data frame". For the sake of completeness, it is noted that another short spelling used here, "start or response data frame", is to be interpreted as "request data frame or response data frame".

0043The present exemplary embodiment offers the advantage of a particularly high process economy. The distance between the first and the second transceiver is not run through four times, but only three times. Fewer steps are needed to determine the distance. This economical procedure is not associated with any loss of measuring accuracy. This goes hand in hand with a reduced energy requirement for the distance measurement, because fewer data frames have to be sent for this.

0044In detail, the two signal circuits of this exemplary embodiment comprise the steps listed individually below.

0045The first round of signals has the following steps:<ul id="ul0002" list-style="none"><li>a1) sending at least a first request data frame, which contains a sequence of at least two signal pulses with a predetermined pulse time interval, from a first transmitter-receiver initiating the signal rounding to a second transmitter-receiver at a first request transmission time,</li><li>b1) receiving the first request data frame at the second transceiver at a first request reception time.</li><li>c1 / a2) Sending a first response data frame, which contains a sequence of at least two signal pulses with a predetermined pulse time interval, from the second transceiver to the first transceiver at a first response transmission time, which has a respective response time interval from the first query reception time and which also has the second query -Send time forms,</li><li>d1 / b2) receiving the first response data frame at the first transceiver initiating the signal rounding and detecting a first response reception time associated with the reception of the first response data frame relative to the first request transmission time.</li></ul>

0046Steps c1) and d1) also form the first two steps of the second signal round, which can therefore also be referred to as steps a2) and b2). These are followed by the following steps at the end of the second signal round:<ul id="ul0003" list-style="none"><li>c2) sending a second response data frame, which contains a sequence of at least two signal pulses with a predetermined pulse interval, from the first transceiver to the second transceiver at a second response transmission time, which has a respective response time interval from the first response reception time,</li><li>d2) Receiving the second response data frame at the second transceiver initiating the signal round and detecting a second response reception time associated with the reception of the second response data frame relative to the first response transmission time, which, as mentioned above, in this exemplary embodiment also forms the second request transmission time.</li></ul>

0047In the context of this application, the present exemplary embodiment is also referred to as a symmetrical three-way method or in short as a three-way method. Further details of this exemplary embodiment are also explained in connection with the detailed description of preferred exemplary embodiments. It can also be expanded by continuing the signal round trips, which enables a higher accuracy of the distance determination.

0048If only one signal round trip initiated by the first transceiver and one by the second transceiver is carried out, the signal runtime becomes <i><b>T</b>_prop</i> between the first and second transceivers according to the formula <maths id="math0001" num="Formel 1:"><math display="block"><mrow><msub><mrow><mi>T</mi></mrow><mrow><mrow><mi mathvariant="italic">prop</mi></mrow></mrow></msub><mo>=</mo><mfrac><mrow><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">roundA</mi><mo>⁢</mo><mn>1</mn></mrow></msub><mo>-</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyB</mi><mo>⁢</mo><mn>1</mn></mrow></msub><mo>+</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">roundB</mi><mo>⁢</mo><mn>2</mn></mrow></msub><mo>-</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyA</mi><mo>⁢</mo><mn>2</mn></mrow></msub></mrow><mrow><mn>4</mn></mrow></mfrac></mrow></math><img file="EP1815267B1_D0001.tif" /></maths> determined This formula is used when the first and second signal rounding are carried out separately or, as in the last described exemplary embodiment, are carried out in a coupled manner. It can therefore be applied to a double-sided two-way process as well as to a three-way process.

0049In a further preferred exemplary embodiment of the method according to the invention, each transceiver initiates at least two signal rounds until the distance between the first and second transceiver has been traversed by a number of request and response data frames which is at least eight and a multiple of four. This means that at least four and multiples of two request data frames and at least four and multiples of two response data frames are transmitted. In this exemplary embodiment, each transceiver 2, 3, 4, .., can initiate n signal round trips. Accordingly, 4 request and 4 answer, 6 request and 6 answer, 8 request and 8 answer, 10 request and 10 answer frames etc. are possible. The sum of all frames is always a multiple of 4. In this embodiment<ul id="ul0004" list-style="dash"><li>become additional round time intervals in addition to the signal round trips initiated by the first transceiver <i><b>T</b>_roundAi</i> with i = 3, 5, 7, .., (n-2) of <i><b>T</b>_roundA3</i> to <i><b>T</b>_{roundA (n-2)}</i> determined, where n> 3 is an odd number, and</li><li>become additional round time intervals for the signal round trips initiated by the second transceiver <i><b>T</b>_{round Bk}</i> with k = 4, 6, 8, .., (n-1) of <i><b>T</b>_{round B4}</i> to <i><b>T</b>_{roundB (n-1)}</i> determined</li><li>where response time intervals <i><b>T</b>_{reply<b>Ak</b>}</i>, k = 2, 4, 6, 8, .., (n-1) of <i><b>T</b>_replyA2</i> to <i><b>T</b>_{replyA (n-1)}</i>, and <i><b>T</b>_replyBi</i>, i = 1, 3, 5, 7, .., (n-2). from<i><b>T</b>_replyB1</i> to <i><b>T</b>_{replyB (n-2)}</i> occur that have a mean difference according to the formula <maths id="math0002" num="Formel 2:"><math display="block"><mrow><mi mathvariant="normal">Δ</mi><mo>⁢</mo><msub><mrow><mi>T</mi></mrow><mrow><mi>re</mi><mrow><mi mathvariant="italic">plyAVG</mi></mrow></mrow></msub><mo>=</mo><mfrac><mrow><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyA</mi><mo>⁢</mo><mn>2</mn></mrow></msub><mo>-</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyB</mi><mo>⁢</mo><mn>1</mn></mrow></msub><mo>+</mo><mn>..</mn><mo>+</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyA</mi><mo>⁢</mo><mfenced separators=""><mi>n</mi><mo>-</mo><mn>1</mn></mfenced></mrow></msub><mo>-</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyB</mi><mo>⁢</mo><mfenced separators=""><mi>n</mi><mo>-</mo><mn>2</mn></mfenced></mrow></msub></mrow><mrow><mfrac><mrow><mi>n</mi><mo>-</mo><mn>1</mn></mrow><mrow><mn>2</mn></mrow></mfrac></mrow></mfrac></mrow></math><img file="EP1815267B1_D0002.tif" /></maths> have a maximum of 200, but preferably a maximum of only 20 microseconds. This formula maps the simple difference of the response time intervals in the case of only one signal round trip initiated by each transceiver to the case of a plurality of signal round trips.</li></ul>

0050In this embodiment, not only one but several signal round trips are initiated by both transmitter receptions. It is therefore the variant of a multiple-sided two-way method already mentioned above. The signal circuits are therefore not coupled, but carried out independently of each other. In this exemplary embodiment, the signal transit time between the first and the second transceiver can therefore be determined with increased accuracy on the basis of the multiplicity of the determined roundness intervals and the detected response intervals, which increases the precision of the distance determination. Details of the calculation of the signal transit time are explained below in the context of the detailed description of preferred exemplary embodiments.

0051In the present exemplary embodiment, the requirement according to the invention for a difference in the response time intervals of at most 200 (preferably 20) microseconds is either replaced by the requirement that an average difference according to the above formula has an amount which is at most 200 (preferably 20) microseconds. This condition is equivalent to the maximum difference of 200 (preferably 20) microseconds required when the first and second signal rounds are carried out once. In one process variant, both conditions are met at the same time.

0052It should be noted that in the present exemplary embodiment, the plurality of signal rounding pairs can occur with a pair of response time intervals, the difference of which has an amount of more than 200 or, in the preferred exemplary embodiment, more than 20 microseconds. However, this is then compensated for by a smaller difference in other response time intervals for other signal round-trip pairs and is therefore an exception. In the present case, the mean time difference of the response time intervals is essential for the accuracy of the distance determination.

0053Even in the coupled implementation of the signal round trips in the context of an exemplary embodiment which forms a symmetrical n-way method, the signal round trips can be carried out several times to increase the precision of the distance determination. In this embodiment<ul id="ul0005" list-style="dash"><li>each transceiver initiates at least two signal rounds until the distance between the first and second transceivers has been traversed by an odd number n> 3 request and response data frames) (i.e. an odd number n> 3 of the sum of all transmitted frames), with all additional round time intervals determined and all additional response time intervals are recorded,</li><li>after the first signal rounding step sequence has been carried out again, additional rounding time intervals <i><b>T</b>_roundAi</i> with i = 3, 5, 7, ..., (n-2), of <i><b>T</b>_roundA3</i> to <i><b>T</b>_{roundA (n-2)}</i> determined and</li><li>after repeated execution of the second signal rounding step sequence, additional rounding time intervals <i><b>T</b>_roundBk,</i> with k = 4, 8, 8, ..., (n-1), of <i><b>T</b>_roundB4</i> to <i><b>T</b>_{roundB (n-1)}</i> determined</li><li>where response time intervals <i><b>T</b>_replyAk,</i> k = 2, 4, 6, 8, ..., (n-1) of <i><b>T</b>_replyA2</i> to <i><b>T</b>_{replyA (n-1)}</i>, <i><b>T</b>_replyBi</i>, i = 1, 3, 5, 7, ..., (n-2) of <i><b>T</b>_replyB1</i> to <i><b>T</b>_{replyB (n-2)}</i> occur that have a mean difference according to the formula <maths id="math0003" num="Formel 3:"><math display="block"><mrow><mi mathvariant="normal">Δ</mi><mo>⁢</mo><msub><mrow><mi>T</mi></mrow><mrow><mi>re</mi><mrow><mi mathvariant="italic">plyAVG</mi></mrow></mrow></msub><mo>=</mo><mfrac><mrow><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyA</mi><mo>⁢</mo><mn>2</mn></mrow></msub><mo>-</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyB</mi><mo>⁢</mo><mn>1</mn></mrow></msub><mo>+</mo><mn>..</mn><mo>+</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyA</mi><mo>⁢</mo><mfenced separators=""><mi>n</mi><mo>-</mo><mn>1</mn></mfenced></mrow></msub><mo>-</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyB</mi><mo>⁢</mo><mfenced separators=""><mi>n</mi><mo>-</mo><mn>2</mn></mfenced></mrow></msub></mrow><mrow><mfrac><mrow><mi>n</mi><mo>-</mo><mn>1</mn></mrow><mrow><mn>2</mn></mrow></mfrac></mrow></mfrac></mrow></math><img file="EP1815267B1_D0003.tif" /></maths> have a maximum of 200, preferably a maximum of 20 microseconds. As already described above in the case of the multiple decoupled execution of signal concentricity pairs in the context of the multiple-double-sided two-way method, this exemplary embodiment enables a more precise determination of the distance and is also explained in more detail below in the context of the detailed description of preferred exemplary embodiments. The request data frames are also response data frames (overlap) at the same time, so that in this exemplary embodiment an odd number of frames is always transmitted.</li></ul>

0054In the above-mentioned exemplary embodiments, which provide for a multiple execution of the first and second signal rounding, the signal transit time is <i><b>T</b>_prop</i> according to the formula <maths id="math0004" num="Formel 4"><math display="block"><mrow><mtable columnalign="left"><mtr><mtd><msub><mrow><mi>T</mi></mrow><mrow><mrow><mi mathvariant="italic">prop</mi></mrow></mrow></msub><mo>=</mo><mfrac><mrow><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">roundA</mi><mo>⁢</mo><mn>1</mn></mrow></msub><mo>-</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyB</mi><mo>⁢</mo><mn>1</mn></mrow></msub><mo>+</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">roundB</mi><mo>⁢</mo><mn>2</mn></mrow></msub><mo>-</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyA</mi><mo>⁢</mo><mn>2</mn></mrow></msub><mo>+</mo><mn>..</mn><mo>+</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">roundA</mi><mo>⁢</mo><mfenced separators=""><mi>n</mi><mo>-</mo><mn>2</mn></mfenced></mrow></msub><mo>-</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyB</mi><mo>⁢</mo><mfenced separators=""><mi>n</mi><mo>-</mo><mn>2</mn></mfenced></mrow></msub><mo>+</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">roundB</mi><mo>⁢</mo><mfenced separators=""><mi>n</mi><mo>-</mo><mn>1</mn></mfenced></mrow></msub><mo>+</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyA</mi><mo>⁢</mo><mfenced separators=""><mi>n</mi><mo>-</mo><mn>1</mn></mfenced></mrow></msub></mrow><mrow><mn>2</mn><mo>⁢</mo><mfenced separators=""><mi>n</mi><mo>-</mo><mn>1</mn></mfenced></mrow></mfrac></mtd></mtr><mtr><mtd><mi>n</mi><mo>=</mo><mn>2</mn><mo>⁢</mo><mi>k</mi><mo>+</mo><mn>1</mn><mo>,</mo><mi>k</mi><mo>∈</mo><mi>N</mi><mo>></mo><mn>1</mn></mtd></mtr></mtable></mrow></math><img file="EP1815267B1_D0004.tif" /></maths> determined

0055In a further exemplary embodiment, the signal round trips are carried out overlapping in time, the request and response data frames of a signal round trip initiated by the first transceiver being transmitted on a different transmission channel than the request and response data frames of a signal round trip initiated by the second transceiver. In this way, the method according to the invention can be carried out more quickly.

0056Various exemplary embodiments of the method according to the invention relate to variants of the evaluation as part of the distance determination. The variants described below can each be combined with all of the exemplary embodiments described above. In a first variant, only the first, in a second variant only the second transceiver determines the spatial distance. The other transceiver transmits the round-trip time interval determined on its side and the response time interval that has occurred there. In a third variant, the two transceivers determine the spatial distance and transmit the previously determined round-trip time intervals and the response time intervals that have occurred to one another.

0057In a fourth variant, a third transceiver determines the spatial distance between the first and second transceivers, and the first and second transceivers transmit the determined round-trip intervals and response intervals beforehand alternatively or additionally to the third transceiver. This does not necessarily have to be a targeted transmission to the third transceiver. This variant can also be carried out so that the third transceiver transmits the round trip. and response time intervals between the first and second transceiver "listens in", thus communicating the round trip and response time intervals from both transceivers.

0058It is also conceivable that only the transmission and reception times are transmitted between the above-mentioned transmitter receptions and then the round trip and response times are determined.

0059In a further exemplary embodiment, the transmitted request and response data frames contain more than two signal pulses and the reception times of more than two signal pulses of a respective request or response data frame are recorded on the part of a respective receiver.

0060The detection of the reception and transmission times of the individual data frames uses a uniform reference time in the data frame, with respect to the times of which are determined. For example, the first signal pulse, in another example the last signal pulse, in another example any other signal pulse within each data frame is agreed or specified as a reference point. The number of signal pulses of the individual data frames can always be different as long as the reference time exists in all data frames.

0061In a further exemplary embodiment, the respective transmitter of a request or response data frame transmits signal pulses of the data frame at transmission times, which are shifted relative to a time grid, which is defined by the transmitter's predetermined pulse interval in the data frame to be transmitted, in such a way that the signal pulses are averaged to those by the time grid predetermined grid times are sent out. Such a procedure is also referred to below as dithering. In this way, the accuracy of the distance determination can be increased further, as will be explained in detail below.

0062Dithering can alternatively or, particularly preferably, additionally be used on the part of a respective receiver to increase the precision of the distance determination. The receiver of a request or response data frame shifts signal pulses of the received data frame relative to a time pattern which is defined by the pulse time interval of the received signal pulses, such that the shifted signal pulses are received on average with the pulse time interval predetermined by the transmitter.

0063A spread of the time shift of a signal pulse of the data frame on the part of the respective transmitter or the respective receiver is preferably greater than the accuracy of a time measurement on the part of the receiver. In the case of dithering generated by both the respective transmitter and the respective receiver, the spread of the sum of the time shifts of a signal pulse on the part of the respective transmitter and the respective receiver is greater than the accuracy of a time measurement on the part of the receiver.

0064When using dithering on the part of the transmitter, the reception times of a plurality of signal pulses contained in a received request or response data frame are preferably recorded relative to a time grid defined by the pulse time interval of the received signal pulses and an agreed reference point in the request or response data frame at the respective receiver of a data frame and saved.

0065In this case, the receiving transceiver in each case determines an average reception time with respect to the time grid after recording the reception times.

0066In a further exemplary embodiment of the invention, when determining a reception time of a signal pulse, the respective receiver determines the time at which a detected signal pulse has a maximum signal gain or a maximum value of a correlation with a predetermined signal pattern

0067After a determination of a reception time of a data frame and before a subsequent determination of a reception time of a next data frame, the respective receiver restarts a clock generator or oscillator used by it to determine transmission and reception times.

0068Alternatively, the respective receiver modulates the frequency of a clock generator or oscillator used by it for determining the transmission and reception times of the signal pulses during the reception of a data frame in accordance with a pseudo-random sequence.

0069In a further exemplary embodiment, errors caused by a multipath propagation of the signal pulses are reduced by the receiver determining the earliest point in time within a predetermined time window at which the received signal has a maximum when a pulse sequence in the received signal due to multipath propagation of an individual signal pulse is present in the received signal Assumes value.

0070In a further exemplary embodiment, the first and second transceivers agree the values ​​of the response time intervals before sending out a request data frame.

0071In order to make the distance determination inaccessible to third parties when the distance determination is carried out several times, the first and second transceivers agree a sequence of different values ​​of response time intervals before sending out a request data frame for the first implementation and adhere to the next response time interval that is subsequently specified in subsequent executions. The first and second transceivers preferably vary the response time interval as a function of an unknown pseudo-random number sequence.

0072A further increase in secrecy is achieved by the first and second transceivers transmitting secretly encrypted messages during the agreement of the response time intervals or the sequence of response time intervals.

0073The first and second transceivers preferably measure the response time interval used by them. The measured response time intervals are used to determine the distance. In this way the accuracy of the method of the invention is ensured.

0074In a further preferred exemplary embodiment of the method according to the invention, the signal pulses used for determining the distance are also used as information symbols

0075It is also particularly preferred to embed the method according to the invention in known transmission protocols of layer 2 of the OSI reference model. An internationally standardized transmission protocol is preferably used, which is in widespread use.

0076In a further particularly preferred exemplary embodiment, the signal pulses are formed by chirp pulses. Chirp pulses with increasing or decreasing frequency response are used. To further increase the accuracy of the distance determination, it is advantageous to use two complementary types of chirp pulses, which have an identical center frequency and pulse duration, but an opposite and symmetrical about the center frequency, increasing with one chirp pulse type and falling with the other chirp pulse type during the pulse duration, wherein the complementary chirp pulse types are used in an inquiry or response data frame in equal numbers in each case for determining the distance. The requirement of symmetry around the center frequency relates to the complementary chirp pulse types in comparison, not to the individual chirp pulse type.

0077In a further exemplary embodiment, a calibration run is carried out in that the first or the second or both transmitter-receivers before a first signal round as part of the distance determination to the respective other transmitter-receiver each have at least one signal round to determine the distance from one or from each with a known distance from the respective transmitter-receiver perform the arranged calibration transmitter-receiver, which additionally uses a response time interval known to the respective transceiver or to be transmitted in each case. The determination of the distance from the calibration transceiver follows the method according to the invention. In this exemplary embodiment, the spatial distance to the calibration transceiver thus determined and the known distance are compared. The comparison result is used for error correction in the context of the subsequent distance determination.

0078In this exemplary embodiment, either a current temperature at the location of a respective transceiver or a current supply voltage of a respective transceiver or both the temperature and the supply voltage are preferably determined before carrying out a distance determination or at intervals of the order of a second before or after.

0079Before or during the calibration, the first or the second or both transceivers save the comparison result for determining error data characteristic of the respective transceiver as a function either of the temperature at the location of a respective transceiver or as a function of the current supply voltage of a respective transceiver or as Function of both of the above parameters. Furthermore, the determined error data are used to determine an individual temperature and supply voltage-dependent error correction function for the respective transmitter receiver or a corresponding error correction table, which are stored in the respective transmitter receiver. Finally, distance values ​​determined in the course of a subsequent distance determination are corrected by using the error correction function or by using a correction value contained in the error table. If the distance is calculated only on the side of a single transceiver, the correction value must be transmitted in addition to the signal round-trip and response time intervals. Alternatively, the signal runout and response time intervals can be corrected before the transmission.

0080In further exemplary embodiments, the method according to the invention can also be used for speed and acceleration measurements. For speed determination, the distance determination is preferably repeated after a predeterminable or dynamically changeable measurement time interval. The dynamic changeability of the measurement time interval means that the measurement time interval can be changed while the speed measurement is being carried out. In this way, with a frequently changing speed, the frequency of the distance measurements can be increased in order to determine a more precise course of the speed of the two transceivers relative to one another. A speed value is determined by forming a distance difference between successively determined distance values ​​between the first and second transmitter-receivers and then forming a quotient from the distance difference and the measurement time interval the speed of the transmitter-receivers relative to one another.

0081In the case of an acceleration measurement with a predeterminable or dynamically variable speed measurement time interval, two speed values ​​are determined.

0082The acceleration of the transceivers is determined relative to one another by forming a speed difference after successively determined speed values ​​and then forming the quotient from the speed difference and the measurement time interval.

0083In a further exemplary embodiment, the number of signal round trips initiated by each transceiver is selected as a function of a predetermined accuracy of the distance determination.

0084In a further exemplary embodiment, the number of signal round trips is selected as a function of a predetermined upper limit of the duration of the distance determination.

0085According to a second aspect of the invention, as a development of the distance determination according to the invention, a method for determining the position of a first transmitter-receiver relative to at least one second transmitter-receiver is provided within a distance range of the order of 10 km, for determining the distance between the first and the or every second Transceiver a method according to one of the preceding claims is used.

0086The advantages of the position determination method according to the invention result from those of the distance determination method of the first aspect of the invention. Exemplary embodiments of the position determination method have the additional features of the exemplary embodiments of the distance determination method according to the invention described in this application either individually or in combination.

0087On the basis of the distance determination, the positions of a transceiver are determined, as is generally customary in methods for determining the position, by trilateration or multilateration with transceivers of known positions.

0088Influences of temperature, supply voltage and specimen scatter as well as the multipath propagation can lead to errors in the pulse transit times, which would result in an ambiguous result of the position during lateration. The distance determination method according to the invention can reduce these errors. More precise position coordinates can be determined by using additional, redundant transceivers with a known position and other known methods of improving the accuracy of the position determination.

0089Errors that arise due to an uneven distribution of the propagation properties of the medium (inhomogeneous multi-path propagation) can also be compensated for, since the distance measured values ​​become noticeable when determining the position and can be taken into account with appropriate weighting. The thus improved precision of the position coordinates of transceivers can in turn be used to improve the calculation of the distance between two transceivers.

0090According to a third aspect of the invention, a transceiver for wireless communication for determining the spatial distance from a second transceiver within a distance range of the order of 10 km is specified with the method according to claim 1.

0091The transceiver has a transmitter unit which is designed to initiate a first signal round to a second transceiver at a first query transmission time by sending out a first query data frame, which contains a sequence of at least two signal pulses with a predetermined pulse interval.

0092Furthermore, the transceiver according to the invention has a receiving unit which is designed to monitor the reception of a first response data frame transmitted in response to the first request data frame from the second transceiver and to detect a first response reception time associated with the reception of the first response data frame relative to the first request transmission time.

0093According to the invention, the transmitter unit is additionally designed<ul id="ul0006" list-style="dash"><li>after receiving a second request data frame initiating a second signal round from the second transceiver, to send a second response data frame, which contains a sequence of at least two signal pulses with a predetermined pulse time interval, to the second transmitter receiver with a response time interval from an assigned second request reception time of the second request data frame,</li><li>after receiving a first request data frame initiating a first signal round from a second transceiver, transmit a first response data frame, which contains a sequence of at least two signal pulses with a predetermined pulse time interval, with a response time interval relative to an assigned first request reception time of the first request data frame to the second transmitter receiver, and</li><li>upon receipt of the first request data frame from the second transceiver, to initiate a second signal round to the second transceiver at a second request transmission time by sending out a second request data frame, which contains a sequence of at least two signal pulses with a predetermined pulse interval,</li></ul>

0094According to the invention, the receiving unit is additionally designed to monitor the reception of a second response data frame transmitted in response to the second request data frame from the second transceiver and to detect a second response reception time associated with the reception of the second response data frame relative to the second request transmission time,

0095Finally, the transceiver according to the invention is designed to transmit the first and the second response data frames with a predetermined value of the response time interval relative to the respective request reception time with a temporal precision in which the response time intervals on the part of the first and second transceivers are either identical in the signal rounds carried out for determining the distance are or a difference if more than one signal round trip initiated by each transceiver is carried out, they have an average difference, the amount of which is a maximum of 200 microseconds, in a preferred exemplary embodiment a maximum of 20 microseconds.

0096Compliance with the described precision of the predetermined response time interval does not require the redesign of clock generators or oscillators to generate the response time interval. On the contrary, for example, commercially available, very inexpensive quartz crystals with a clock accuracy of ± 50 ppm or ± 20 ppm or clock generators derived from quartz oscillator clocks are used without their errors causing any appreciable deterioration in accuracy. In this way, an accuracy of the distance determination that was previously not considered possible with such simple means is achieved. Compliance with the precision described, however, requires that two transceivers according to the present invention be used to determine the distance.

0097The method according to the invention is based on the compensation of errors caused by quartz crystals by means of a symmetrical distance measurement which is initiated by the two transmitter receivers involved. In a variant of the method according to the invention, which in particular reduces the energy and channel bandwidth required for the distance measurement, the method according to the invention is carried out before a distance determination, which only comprises a single signal round trip. With this method, a clock generator error of both transceivers is also determined. The concentricity measurements of the method according to the invention can be used to determine the clock generator error. For a subsequent determination of the distance, which relates to at least one of the two transmitter-receivers of the previous distance measurement, only a single signal round trip is initiated, in deviation from the method according to the invention. An evaluation step is then carried out to determine the distance on the basis of this individual signal round trip. In the evaluation step of this subsequent distance determination, a falsification is calculated on the basis of the single signal round-trip provisionally determined distance value on the basis of the previously determined clock generator error of the transceiver in question for the final determination of the distance value. A clock drift can therefore be eliminated with the previously calculated and stored value. In this way it is made possible that in a series of distance determinations, not all distance determinations of both transmitter-receivers have to contain concentricity measurements, which in addition to saving energy also means saving channel bandwidth.

0098This exemplary embodiment has a lower accuracy than the continuous repetition of the method according to the invention. However, this reduced accuracy can be sufficient in a variety of applications. The method requires the establishment and maintenance of a database of crystal or clock generator errors in one of the transceiver stations (for example a central ranging station). Applications with many network nodes and high network utilization, in which the bandwidth used and the battery life are important, will often contain a central or coordinating unit that will take over the function of the ranging station. This ranging station will usually also contain the application with a database of information required, for example an application for tracking transceivers. Such stations are not subject to the same cost pressure as mobile devices.

0099Since crystal errors can change due to temperature variations, the coordinating ranging station preferably updates the database with crystal errors on a regular basis. Alternatively, such an update can also be initiated by temperature changes measured in a mobile device. However, it must be taken into account that the temperature changes typically take place only slowly and that the entire temperature range of - 40 ° C to 85 ° C relevant for quartz crystals is hardly covered within a short time. Therefore, crystal error measurements with the method according to the invention only have to be carried out relatively rarely, and the error values ​​stored in the database are mostly valid for a longer time.

0100Typically, the protocol for performing a ranging will be located at a higher protocol level together with other functions, such as security functions. This favors a smooth cooperation between the ranging functionality and an application, such as the tracking application, when maintaining the database.

0101Exemplary embodiments of the transceiver according to the invention are described below. It is pointed out that exemplary embodiments of the transceiver are also mentioned in the claims. Furthermore, further exemplary embodiments of the transceiver result from implementation of the additional features of the above-described exemplary embodiments of the method according to the invention for determining the distance and of the method according to the invention for determining the position. The method features described there can be implemented in electronic circuits using known methods of hardware or software design. Furthermore, it should be noted that the exemplary embodiments described here can be implemented both individually and in combination with one another, unless the contrary is apparent from the description or the claims

0102In a preferred exemplary embodiment, the transceiver has an evaluation unit which is connected to the transmitter and receiver unit and is designed to determine a round trip interval between the request-transmit time of a first or second request data frame sent by the transmitter unit and the response-reception time of one of the second transmitter-receiver received first or second response data frame.

0103In this exemplary embodiment, the evaluation unit preferably has a data connection to the second transmitter-receiver and is additionally designed to transmit a detected response time interval and a determined round-trip time interval to the second transmitter-receiver via the transmitter unit, or to receive a detected response time interval and a determined round-trip time interval on the part of the second transmitter-receiver via the reception unit and a signal delay T_prop to determine between the first and the second transceiver on the basis of the determined round-trip time interval and the response time intervals and the spatial distance between the first and second transceiver by multiplying the signal transit time T_prop to determine with a known propagation speed of the signal pulses.

0104In a further exemplary embodiment of the transceiver according to the invention, the transmitter unit is designed to send the second request data frame to the second transceiver to initiate the second signal round after the first response data frame.

0105In another exemplary embodiment, the transmission unit is designed to transmit a combined request and response data frame to the second transceiver at the second request transmission time with the predetermined response time interval relative to an assigned reception time of the first request data frame, which data frame functions both as a first response data frame and in a single data frame also combines the function of a second request data frame, and in which the receiving unit is designed to monitor the reception of a second response data frame transmitted in response to the combined request and response data frame from the second transceiver and to detect a second response reception time associated with the reception of the second response data frame relative to the second request transmission time.

0106In a further exemplary embodiment, the transmitting unit is designed to transmit request data frames and response data frames each with more than two signal pulses, and in which the receiving unit is designed to detect the reception times of more than two signal pulses of a respective request or response data frame.

0107In this exemplary embodiment, the transmission unit is preferably designed to transmit signal pulses of a data frame at transmission times that are shifted relative to a time grid that is defined by the transmitter's predetermined pulse interval in the data frame to be transmitted such that the signal pulses on average at the grid times specified by the time grid be sent out.

0108The receiving unit is preferably designed to shift signal pulses of a received data frame relative to a time grid, which is defined by the pulse time interval of the received signal pulses, such that the shifted signal pulses are received on average with the pulse time interval predetermined by the transmitter. The reception unit is preferably designed to determine an average reception time with respect to the time grid after detection of the reception times of the signal pulses.

0109In one exemplary embodiment with a particularly precise determination of reception times, the reception unit is designed to determine that time and to record it as the reception time of a signal pulse at which a detected signal pulse has a maximum signal gain or a maximum value of a correlation with a predetermined signal pattern.

0110In a further exemplary embodiment, the receiving unit is designed, after a determination of a request or response reception time of a request or response data frame and before a subsequent determination of a request or response reception time of a next request or response data frame, one for determining transmission and reception times restart the used clock generator or oscillator.

0111The receiving unit is preferably designed to check a received signal for the presence of a pulse sequence based on a multipath propagation of an individual signal pulse and, if such a pulse sequence is present, to determine the earliest point in time within a predetermined time window at which the received signal assumes a maximum value as the reception time of the signal pulse

0112In another embodiment, the transceiver is designed to agree the values ​​of the response time intervals with the second transceiver before sending out a request data frame.

0113A particularly preferred exemplary embodiment of the transceiver according to the invention is designed to measure the response time interval.

0114A further exemplary embodiment of the transceiver according to the invention is designed to agree a sequence of different values ​​of response time intervals with the second transceiver and to comply with the next response interval specified in the sequence when carrying out each subsequent distance determination.

0115A transceiver in which the transmitter unit is designed to use the signal pulses used for determining the distance as information symbols is particularly preferred.

0116Furthermore, the transmitting unit is particularly preferably designed to send out generated signal pulses in the form of chirp pulses and the receiving unit is designed to reconstruct signal pulses generated on the transmitter side from received chirp pulses.

0117It is advantageous if the transmitter unit is designed to emit two complementary types of chirp pulses, which have an identical center frequency and pulse duration, but an opposite and symmetrical around the center frequency, increasing with one chirp pulse type and falling with the other chirp pulse type during the frequency response Have pulse duration, wherein the complementary chirp pulse types are used in a request or response data frame in equal numbers in each case for determining the distance. A preferred exemplary embodiment of a transceiver with an evaluation unit is designed to repeat the distance determination after a predeterminable or dynamically changeable measurement time interval, and in which the evaluation unit is designed, to determine the speed of the transceivers relative to one another by forming a distance difference between successively determined distance values ​​between the first and second transceivers and then forming a quotient from the distance difference and the measurement time interval.

0118A further exemplary embodiment of the transceiver according to the invention is designed to measure acceleration, to determine two speed values ​​with a predeterminable or dynamically variable speed measurement time interval, and in which the evaluation unit is designed, to determine the acceleration of the transceivers relative to one another by forming a speed difference after successively determined speed values ​​and then forming the quotient from the speed difference and the measurement time interval.

0119According to a fourth aspect of the invention, an arrangement for determining the spatial distance between a first transceiver according to the invention and a second transceiver according to the invention is provided within a distance range of the order of 10 km.

0120The advantages of the arrangement according to the invention result from the advantages of the method according to the invention described above. Exemplary embodiments of the arrangement according to the invention, insofar as they are not described in more detail below and in the patent claims, correspond to the exemplary embodiments of the transceiver according to the invention.

0121The additional features of further exemplary embodiments of the arrangement according to the invention are described below.

0122In a preferred embodiment of the arrangement according to the invention, both transceivers have an evaluation unit which is connected to the respective transmitter unit and the respective receiver unit of the transceiver and is designed, for determining a round trip interval between the transmission time of a first or second request data frame sent by the transmission unit and the reception time of a first or second response frame received by the second transceiver.

0123A further exemplary embodiment of the arrangement according to the invention has a third transceiver, which has a distance determination unit with a data connection to the first and to the second transceiver. The third transmitter-receiver is designed, a data connection to the first and second transmitter-receivers for the transmission of round-trip intervals and response intervals to the third transmitter-receiver. Furthermore, the distance determination unit is designed, and<ul id="ul0007" list-style="dash"><li>to determine a signal transit time between the first and the second transceiver on the basis of the determined round trip interval and the response interval and</li><li>for calculating the spatial distance between the first and second transceivers by multiplying the signal transit time T_prop with a known propagation speed of the signal pulses.</li></ul>

0124In a further exemplary embodiment of the arrangement according to the invention, the first and second transceivers are designed to carry out the first and second signal rounding at least twice until the distance between the first and second transceivers has been traversed by a number of request and response data frames which is a multiple of four is to be determined, as well as all additional round trips and response time intervals, wherein the first and second transceivers are formed, response time intervals T_replyAk, k = 2, 4, 6, 8, .., (n-1) of T_replyA2 to T_{replyA (n-1)}, and T_replyB1, i = 1, 3, 5, 7, ..., (n-2) of T_replyB1 to T_{replyB (n-2)} to use a mean difference according to the formula <maths id="math0005" num=""><math display="block"><mrow><mi mathvariant="normal">Δ</mi><mo>⁢</mo><msub><mrow><mi>T</mi></mrow><mrow><mi>re</mi><mrow><mi mathvariant="italic">plyAVG</mi></mrow></mrow></msub><mo>=</mo><mfrac><mrow><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyA</mi><mo>⁢</mo><mn>2</mn></mrow></msub><mo>-</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyB</mi><mo>⁢</mo><mn>1</mn></mrow></msub><mo>+</mo><mn>..</mn><mo>+</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyA</mi><mo>⁢</mo><mfenced separators=""><mi>n</mi><mo>-</mo><mn>1</mn></mfenced></mrow></msub><mo>-</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyB</mi><mo>⁢</mo><mfenced separators=""><mi>n</mi><mo>-</mo><mn>2</mn></mfenced></mrow></msub></mrow><mrow><mfrac><mrow><mi>n</mi><mo>-</mo><mn>1</mn></mrow><mrow><mn>2</mn></mrow></mfrac></mrow></mfrac></mrow></math><img file="EP1815267B1_D0005.tif" /></maths> have a maximum of 200, preferably a maximum of 20 microseconds. The evaluation unit of the first transceiver is designed here, after repeated execution of the first signal rounding step sequence, additional rounding time intervals T_roundAi with i = 3, 5, 7, ..., (n-2) of T_roundA3 to T_{roundA (n-2)} to determine, where n is an odd number.

0125In this exemplary embodiment, the evaluation unit of the second transceiver is further designed, after repeated execution of the second signal rounding step sequence, additional rounding time intervals T_roundBk with k = 4, 6, 8, ..., (n-1) of T_roundB4 to T_{roundB (n-1)} to investigate.

0126In a further exemplary embodiment of the arrangement according to the invention, in which the transceivers are designed to carry out a symmetrical three-way method, each transceiver is preferably designed to initiate at least two signal round trips until the distance between the first and second transceivers has an odd number n> 3 request and response data frames have been run through, as well as determine all additional concentricity intervals and record response time intervals.

0127With this arrangement<ul id="ul0008" list-style="dash"><li>after repeated execution of the first signal rounding step sequence, additional rounding time intervals T_roundAi with i = 3, 5, 7, ..., (n-2), from T_roundA3 to T_{roundA (n-2)} determined and</li><li>after repeated execution of the second signal rounding step sequence, additional rounding time intervals T_roundBk, with k = 4, 8, 8, ..., (n-1), from T_roundB4 to T_{roundB (n-1)} determined</li><li>where response time intervals T_replyAk, k = 2, 4, 6, 8, ..., (n-1) of T_replyA2 to T_{replyA (n-1)}, T_replyBi, i = 1, 3, 5, 7, ..., (n-2) of T_replyB1 to T_{replyB (n-2)} occur that have a mean difference according to the formula <maths id="math0006" num=""><math display="block"><mrow><mi mathvariant="normal">Δ</mi><mo>⁢</mo><msub><mrow><mi>T</mi></mrow><mrow><mi>re</mi><mrow><mi mathvariant="italic">plyAVG</mi></mrow></mrow></msub><mo>=</mo><mfrac><mrow><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyA</mi><mo>⁢</mo><mn>2</mn></mrow></msub><mo>-</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyB</mi><mo>⁢</mo><mn>1</mn></mrow></msub><mo>+</mo><mn>..</mn><mo>+</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyA</mi><mo>⁢</mo><mfenced separators=""><mi>n</mi><mo>-</mo><mn>1</mn></mfenced></mrow></msub><mo>-</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyB</mi><mo>⁢</mo><mfenced separators=""><mi>n</mi><mo>-</mo><mn>2</mn></mfenced></mrow></msub></mrow><mrow><mfrac><mrow><mi>n</mi><mo>-</mo><mn>1</mn></mrow><mrow><mn>2</mn></mrow></mfrac></mrow></mfrac></mrow></math><img file="EP1815267B1_D0006.tif" /></maths> have a maximum of 200, preferably a maximum of 20 microseconds.</li></ul>

0128In a further exemplary embodiment of the arrangement according to the invention, an additional calibration transmitter-receiver with an evaluation unit is provided, which is arranged at a known distance from the first or second transmitter-receiver and which uses a response time interval which is known or in each case to be transmitted

0129In this exemplary embodiment, the first or the second or both transmitter-receivers are designed to carry out at least one pair of signal circuits for determining the distance from the calibration transmitter-receiver as part of the determination of the distance to the other transmitter-receiver before a first signal round trip.

0130Furthermore, the first or second transmitter-receiver is designed to compare the spatial distance to the calibration transmitter-receiver determined in this way and to be known and to use the comparison result in the context of the subsequent distance determination for error correction.

0131In a preferred embodiment of the arrangement according to the invention, the first or the second transceiver or both transceivers are designed, to measure either a current temperature at the location of a respective transceiver or a current supply voltage of a respective transceiver or both the current temperature and the current supply voltage during the execution of a distance determination or at the interval of the order of a second before or after.

0132By using temperature-insensitive components, which are used in particular for the detection of the pulses in the receiver, the negative influences of the ambient temperature or manufacturing tolerances can be avoided.

0133In practice, mechanical surface wave filters that show a strong temperature dependence are often used to compress a pulse. In addition, these components have properties that are dependent on the specimen, which are due to the mechanical tolerances of the manufacture and cause different temporal behavior. The temporal errors would lead to great inaccuracies in the distance measurement.

0134The principle of operation of these analog components in the transceiver according to the invention is therefore preferably implemented in digital electronic circuits which have significantly less dependence on temperature and manufacturing tolerances. For example, the compression of a chirp pulse, which is used for the transmission of information symbols, can be implemented in the receiver with a digital correlator as an electronic circuit.

0135In one exemplary embodiment of an arrangement according to the invention for determining the spatial distance between a first transceiver and a second transceiver according to the invention, a database unit is provided in one of the transceivers, which is designed to determine and store clock generator errors from transceivers on the basis of a previously determined distance determination. The first and the second transmitter-receivers are designed, after determining their clock generator errors, to carry out the following distance determinations, in deviation from the method according to the invention, with only a single signal round-trip and with one evaluation step. The evaluation unit of the transceiver is designed to calculate, in the evaluation step, a falsification of a distance value preliminarily determined after the single signal round with access to the clock generator error of the participating transceiver previously stored in the database unit for the final determination of the distance value. With this arrangement, the previously described method is implemented, in which the method according to the invention is carried out at regular intervals, and in the meantime a simpler distance determination method is carried out with only a single signal round trip.

BRIEF DESCRIPTION OF THE FIGURES

0136<dl id="dl0001"><dt>FIG. 1</dt><dd>shows a schematic representation of an embodiment of the method according to the invention in the form of a 3-way method.</dd><dt>FIG. 2nd</dt><dd>shows a timing diagram for explaining the timing of the 3-way method of FIG <figref idref="f0001">Figure 1</figref>.</dd><dt>FIG. 3rd</dt><dd>shows a second embodiment of the invention in the form of a generalized n-way method, in which the distance between two transceivers is traversed by an odd number of data frames.</dd><dt>FIG. 4th</dt><dd>shows a timing diagram to explain the timing of the n-way method of the <figref idref="f0002">Figure 4</figref>.</dd><dt>FIG. 5</dt><dd>shows a third embodiment of the method according to the invention for determining the distance in the form of a double-sided two-way method.</dd><dt>FIG. 6</dt><dd>shows a timing diagram for explaining the timing of the double-sided two-way method of the <figref idref="f0003">Figure 6</figref>.</dd><dt>FIG. 7</dt><dd>shows a schematic * representation to explain a fourth embodiment in which a multiple-double-sided two-way method is carried out by repeating signal rounds.</dd><dt>FIG. 8th</dt><dd>shows a timing diagram to explain the timing of the multi-sided two-way method of the <figref idref="f0004">Figure 8</figref>.</dd><dt>FIG. 9</dt><dd>shows a timing diagram for explaining a fifth embodiment in which dithering is carried out on the transmitter side.</dd><dt>FIG. 10th</dt><dd>shows a timing diagram to explain the receiver-side behavior in the case of transmitter-side dithering according to <figref idref="f0005">Figure 10</figref>.</dd><dt>FIG. 11</dt><dd>shows an example of an arrangement of two transceivers with inherently implemented dithering based on a block diagram.</dd><dt>FIG. 12th</dt><dd>shows a timing diagram for explaining the timing of the transmission of a pulse when using the transceiver arrangement of the <figref idref="f0006">Fig. 11</figref>.</dd><dt>FIG. 13</dt><dd>shows for further explanation of the transceiver arrangement of the <figref idref="f0006">Fig. 11</figref> a time diagram to explain the time resolution of the individual measurements.</dd><dt>FIG. 14</dt><dd>shows on the basis of a block diagram an embodiment variant of a transceiver according to the invention with external distance calculation and application module implemented in an integrated circuit module.</dd><dt>FIG. 15</dt><dd>shows in a block diagram an embodiment of a transceiver with an integrated distance calculation module.</dd><dt>FIG. 16</dt><dd>shows in a block diagram an embodiment of a transceiver, which is characterized by an integrated distance calculation and application module.</dd><dt>FIG. 17th</dt><dd>shows in a block diagram an embodiment of a transceiver with an implementation of the measurement of the round trip interval and the response interval.</dd><dt>FIG. 18th</dt><dd>shows in a block diagram an embodiment of a transceiver, which implements a measurement of the round trip interval and additionally a measurement of the error of the round trip interval.</dd><dt>FIG. 19th</dt><dd>shows in a block diagram an embodiment of a transceiver, which implements a controller for generating the response time interval and additionally a measurement of the error of the response time interval.</dd><dt>Fig. 20</dt><dd>shows a block diagram of a transceiver that implements an averaging method</dd></dl>

DESCRIPTION OF PREFERRED EMBODIMENTS

0137A number of preferred exemplary embodiments are described in more detail below with reference to the figures mentioned.

1. Three-way method for determining the distance

0138A 3-way method for determining the distance between two transceivers is described below as the first exemplary embodiment of the invention with reference to FIGS. 1 and 2. In this embodiment, the first and second signal rounding described above are coupled. The chronological sequence of the signal rounds is first described. The accuracy of the distance measurement according to this exemplary embodiment is then discussed in detail.

1.1 Signal circuits in the three-way process

0139<figref idref="f0001">Figure 1</figref> shows a schematic representation of the 3-way method for determining the distance between a first transceiver A and a second transceiver B. The designation 3-way was chosen because a total of three data frames are transmitted as part of the distance determination.

0140The transceiver A transmits a first data frame 10 to the second transceiver B. The data frame 10 consists of a sequence of signal pulses with a known frequency of the signal pulses.

0141The data frame 10 is received by the transceiver B, checked and, if the check is successful, sent by sending a second data frame 12 to the first transceiver A. The structure of the second data frame corresponds to that of the first data frame. This does not mean that data frames 10 and 12 must be identical. They have a sequence of signal pulses with a known pulse frequency only for the purpose of distance determination. Different additional messages can be transmitted with the data frames.

0142The first transceiver A checks the received second data frame 12 and sends a third data frame 14 to the second transceiver B after a successful check from <figref idref="f0001">Figure 2</figref> is explained in more detail.

0143<figref idref="f0001">Figure 2</figref> shows a timing diagram for explaining the timing of the 3-way method of FIG <figref idref="f0001">Figure 1</figref>. In the diagram of the<figref idref="f0001">Figure 2</figref> Two time axes 20 and 22 are shown, which represent the temporal course of the transmission and reception activities of the first transceiver A on the time axis 20 and of the second transceiver B on the time axis 22. To simplify the display of each data frame<figref idref="f0001">Figure 1</figref> in <figref idref="f0001">figure 2</figref> only one signal pulse shown This corresponds to the actual situation in that a reference point must be agreed within the data frame in order to determine the times of transmission and reception. A suitable reference point is the time of the maximum amplitude of a specific signal pulse of the data frame, for example the first signal pulse (frame start) or the last signal pulse (frame end). Another reference point can also be agreed between the transceivers A and B.

0144At a time T_TA1 the first transceiver A sends the first data frame 10 to the second transceiver B. The latter receives the first data frame 10 in the form of a received signal 10 'after a signal propagation time T caused by the distance between the transceivers A and 8 and the propagation speed of the medium_prop. Received data frames such as the data frame 10 'as such are distinguished from the transmitted data frame by a prime in the context of this description for the sole reason that they are received signals which are due to multiple propagation, signal attenuations and similar known effects from the respectively transmitted data frame can distinguish. Ideally, a sent and a received data frame do not differ

0145After checking the received data frame 10 ', the second transceiver B sends the second data frame 12 to the first transceiver A. The time interval between the reception time T_RB1 of the first data frame 10 'and the transmission time T_TB1 of the second data frame 12 is the response time interval T_replyB. The first transceiver A receives the second data frame 12 after the signal propagation time T._prop in the form of a reception signal 12 'at a reception time T_RA1. The time interval between the first transmission time T_TA1 and the reception time T_RA1 on the side of the transceiver A forms a first round trip interval T_roundA1.

0146The first transceiver A replies to the reception of the second data frame 12 with the third data frame 14. In this case, the time between the receipt of the received signal 12 'at time T passes_RA1 and sending out the third data frame 14 at time T._TA2 a time interval T_replyA2. After a signal run time T_prop the third data frame 14 reaches the second transceiver B at a reception time T._RB2.

0147Between the transmission of the second data frame 12 and the reception of the third data frame 14 at the second transceiver B, a second signal round-trip takes place, which has a total duration T_roundB2 needed.

0148An essential feature of the present method is that the first round of signals begins and ends at the first transceiver A, while the second round of signals begins and ends at the second transceiver B. Furthermore, an essential feature of the exemplary embodiment described here is that the response time intervals T_replyB1 and T_replyA2 are identical or have a difference, the maximum amount of which is 20 µs. The response time intervals can be caused by response times, which are defined in transmission protocols, by the length or duration of the transmitted data frames as well as by device-internal delays caused by the frame check or other processes within a transceiver.

0149From the round trip intervals T_roundA1 and T_roundB2 After deducting the known response times, an average signal delay in the transmission medium is determined. The following formula is used for this: <maths id="math0007" num=""><math display="block"><mrow><msub><mrow><mi>T</mi></mrow><mrow><mrow><mi mathvariant="italic">prop</mi></mrow></mrow></msub><mo>=</mo><mfrac><mrow><msub><mi>T</mi><mi mathvariant="italic">roundA</mi></msub><mo>-</mo><msub><mi>T</mi><mi mathvariant="italic">replyB</mi></msub><mo>+</mo><msub><mi>T</mi><mi mathvariant="italic">roundB</mi></msub><mo>-</mo><msub><mi>T</mi><mi mathvariant="italic">replyA</mi></msub></mrow><mrow><mn>4</mn></mrow></mfrac></mrow></math><img file="EP1815267B1_D0007.tif" /></maths>

0150From the mean signal transit time T determined according to formula (6)_prop the distance d is determined as follows on the basis of a known propagation speed of the data frames in the transmission medium between the transceivers A and B: <maths id="math0008" num="Formel 6:"><math display="block"><mrow><mi>d</mi><mo>=</mo><msub><mi mathvariant="italic">cT</mi><mi mathvariant="italic">prop</mi></msub><mn>.</mn></mrow></math><img file="EP1815267B1_D0008.tif" /></maths>

0151In the above description it was assumed that the distance between the transceivers A and B does not change during the measurement. To a good approximation, this is a valid assumption even with moving transceivers. Also, to simplify the display of error-free round time intervals T_round and response time intervals T_reply went out. In practice, one naturally calculates with erroneous values ​​and the method according to the invention determines the distance in spite of erroneous values ​​with the accuracy explained above. The details given here for accuracy are based on an error analysis that takes into account incorrect runout and response time intervals.

1.2 Accuracy of the distance determination

0152For the purpose of the following illustration, the symbols used in the above formula (2) are simplified in their indices without changing their meaning. The simplified formula (2 ') has the same meaning as formula 2:<maths id="math0009" num="Formel 6':"><math display="block"><mrow><msub><mrow><mi>T</mi></mrow><mrow><mrow><mi mathvariant="italic">prop</mi></mrow></mrow></msub><mo>=</mo><mfrac><mrow><msub><mi>T</mi><mi mathvariant="italic">roundA</mi></msub><mo>-</mo><msub><mi>T</mi><mi mathvariant="italic">replyB</mi></msub><mo>+</mo><msub><mi>T</mi><mi mathvariant="italic">roundB</mi></msub><mo>-</mo><msub><mi>T</mi><mi mathvariant="italic">replyA</mi></msub></mrow><mrow><mn>4</mn></mrow></mfrac></mrow></math><img file="EP1815267B1_D0009.tif" /></maths>

0153Clock generators of both transceivers A and B, which are used for measuring the round trip intervals and determining the response times, generally have errors due to implementation variants of the circuits, temperature influences, manufacturing tolerances and aging.

0154This results in a deviation of the clock frequency of the clock generators from their nominal frequency. Due to the nominal frequency deviations at both transceivers, error-prone concentricity intervals (<i>T_roundA</i>', <i>T_roundB</i>') measured. In addition, incorrect response times (<i>T_replayA</i>', <i>T_replyB</i>') generated. This results in the relative error E for the calculated pulse transit time or the distance calculated from it_tab according to formula 7 below: <maths id="math0010" num="Formel 7:"><math display="block"><mrow><msub><mrow><mi>T</mi></mrow><mrow><mrow><mi mathvariant="italic">prop</mi></mrow></mrow></msub><mo>⁢</mo><mfenced separators=""><mn>1</mn><mo>+</mo><msub><mi>E</mi><mi mathvariant="italic">tab</mi></msub></mfenced><mo>=</mo><mfrac><mrow><msub><mi>T</mi><mi mathvariant="italic">roundA</mi></msub><mo>⁢</mo><mi>ʹ</mi><mo>-</mo><msub><mi>T</mi><mi mathvariant="italic">replyB</mi></msub><mo>⁢</mo><mi>ʹ</mi><mo>+</mo><msub><mi>T</mi><mi mathvariant="italic">roundB</mi></msub><mo>⁢</mo><mi>ʹ</mi><mo>-</mo><msub><mi>T</mi><mi mathvariant="italic">replyA</mi></msub><mo>⁢</mo><mi>ʹ</mi></mrow><mrow><mn>4</mn></mrow></mfrac></mrow></math><img file="EP1815267B1_D0010.tif" /></maths>

0155The nominal frequency deviations are shown as relative deviations or time errors (E_tA and E_tB) of the measured or generated times from the actual time intervals according to Formula 8 to Formula 11 as follows: <maths id="math0011" num="Formel 8:"><math display="block"><mrow><msub><mi>T</mi><mi mathvariant="italic">roundA</mi></msub><mo>⁢</mo><mi>ʹ</mi><mo>=</mo><msub><mi>T</mi><mi mathvariant="italic">roundA</mi></msub><mo>⁢</mo><mfenced separators=""><mn>1</mn><mo>+</mo><msub><mi>E</mi><mi mathvariant="italic">tA</mi></msub></mfenced></mrow></math><img file="EP1815267B1_D0011.tif" /></maths><maths id="math0012" num="Formel 9:"><math display="block"><mrow><msub><mi>T</mi><mi mathvariant="italic">replyA</mi></msub><mo>⁢</mo><mi>ʹ</mi><mo>=</mo><msub><mi>T</mi><mi mathvariant="italic">replyA</mi></msub><mo>⁢</mo><mfenced separators=""><mn>1</mn><mo>+</mo><msub><mi>E</mi><mi mathvariant="italic">tA</mi></msub></mfenced></mrow></math><img file="EP1815267B1_D0012.tif" /></maths><maths id="math0013" num="Formel 10:"><math display="block"><mrow><msub><mi>T</mi><mi mathvariant="italic">roundB</mi></msub><mo>⁢</mo><mi>ʹ</mi><mo>=</mo><msub><mi>T</mi><mi mathvariant="italic">roundB</mi></msub><mo>⁢</mo><mfenced separators=""><mn>1</mn><mo>+</mo><msub><mi>E</mi><mi mathvariant="italic">tB</mi></msub></mfenced></mrow></math><img file="EP1815267B1_D0013.tif" /></maths><maths id="math0014" num="Formel 11:"><math display="block"><mrow><msub><mi>T</mi><mi mathvariant="italic">replyB</mi></msub><mo>⁢</mo><mi>ʹ</mi><mo>=</mo><msub><mi>T</mi><mi mathvariant="italic">replyB</mi></msub><mo>⁢</mo><mfenced separators=""><mn>1</mn><mo>+</mo><msub><mi>E</mi><mi mathvariant="italic">tB</mi></msub></mfenced></mrow></math><img file="EP1815267B1_D0014.tif" /></maths>

0156The error of the pulse transit time or the distance (E_tab) is determined as follows: <maths id="math0015" num="Formel 12:"><math display="block"><mrow><msub><mi>E</mi><mi mathvariant="italic">tab</mi></msub><mo>=</mo><msub><mrow><mi>½</mi><mrow><mi>E</mi></mrow></mrow><mrow><mi mathvariant="italic">tA</mi></mrow></msub><mo>+</mo><msub><mrow><mi>½</mi><mrow><mi>E</mi></mrow></mrow><mrow><mi mathvariant="italic">tB</mi></mrow></msub><mo>+</mo><mfrac><mrow><msub><mi>T</mi><mi mathvariant="italic">replyA</mi></msub><mo>-</mo><msub><mi>T</mi><mi mathvariant="italic">replyB</mi></msub></mrow><mrow><mn>4</mn><mo>⁢</mo><msub><mi>T</mi><mi mathvariant="italic">prop</mi></msub></mrow></mfrac><mo>⁢</mo><mfenced separators=""><msub><mi>E</mi><mi mathvariant="italic">tB</mi></msub><mo>-</mo><msub><mi>E</mi><mi mathvariant="italic">tA</mi></msub></mfenced></mrow></math><img file="EP1815267B1_D0015.tif" /></maths>

0157In order to be able to better estimate the effects of the pulse transit time or the distance, the following two cases of the nominal frequency deviations (time errors) are assumed.<ol id="ol0002" ol-style=""><li>a) The relative time errors are both the same size (EtA = EtB).</li><li>b) The amount of the relative time errors is the same, but with a different sign (EtA = - EtB).</li></ol>

0158In case a) the relative error of the distance corresponds to the arithmetic mean of the relative time errors according to the following formula 13: <maths id="math0016" num="Formel 13:"><math display="block"><mrow><msub><mi>E</mi><mi mathvariant="italic">tab</mi></msub><mo>=</mo><msub><mrow><mi mathvariant="normal">½</mi><mrow><mi>E</mi></mrow></mrow><mrow><mi mathvariant="italic">tA</mi></mrow></msub><mo>+</mo><msub><mrow><mi mathvariant="normal">½</mi><mrow><mi>E</mi></mrow></mrow><mrow><mi mathvariant="italic">tB</mi></mrow></msub></mrow></math><img file="EP1815267B1_D0016.tif" /></maths>

0159In practice, the latter are very small. For example, commercially available and very inexpensive quartz crystals have an error of less than ± 0.005% over a temperature range of -40 to 85 ° C. This results in a very small error in the distance measurement. In this case, the precision of the distance measurement is also independent of the absolute runout and response times - the time errors only affect the pulse runtime.

0160In case b), the relative error essentially depends on the ratio of the response time difference (T_replyA - T_replyB) - at four times the pulse duration (see formula 14). <maths id="math0017" num="Formel 14:"><math display="block"><mrow><msub><mi>E</mi><mi mathvariant="italic">tab</mi></msub><mo>=</mo><mfrac><mrow><msub><mi>T</mi><mi mathvariant="italic">replyA</mi></msub><mo>-</mo><msub><mi>T</mi><mi mathvariant="italic">replyB</mi></msub></mrow><mrow><mn>4</mn><mo>⁢</mo><msub><mi>T</mi><mi mathvariant="italic">prop</mi></msub></mrow></mfrac><mfenced separators=""><mn>2</mn><mo>⁢</mo><msub><mi>E</mi><mi mathvariant="italic">tA</mi></msub></mfenced></mrow></math><img file="EP1815267B1_D0017.tif" /></maths>

0161At this point, an essential advantage of the method implementation according to the invention is evident: the compliance of very small response time differences according to the invention improves the precision of the distance measurement. In the case of identical response time intervals, the precision of the distance measurement is independent of the absolute concentricity and response time intervals. The ideal case of identical time intervals is approximated sufficiently precisely by observing a maximum difference in the response time intervals of a maximum of 20 microseconds. While the upper limit of 20 microseconds represents the currently preferred exemplary embodiment, it should be pointed out that the method according to the invention can still be used to carry out a distance measurement that is sufficiently accurate for many applications, even if the response time intervals differ by a maximum of 200 microseconds.

0162In order to clarify the validity of these findings, the influence of the response time differences on the precision of the distance measurement was based on concrete numerical values ​​for different distances (i.e._FROM) and different response time differences (ΔT_reply = T_replyA - T_replyB) calculated. A group of constellations with different pairs of relative time error values ​​(E_tA, E_tB), which in the interval E_tA = -50..0..50 ppm and E_tB = -50..0..50 ppm, the distance measurement errors are calculated using formula 15. Then the pair with the greatest error of distance measurement was Δ_dAB This determines the maximum error of the distance measurement Δ_dAB are in the table below depending on the distance between the first and second transceivers and on the difference between the response time intervals Δ<i>T_reply</i> shown.<tables id="tabl0001" num="0001"><table frame="all"><tgroup cols="6"><colspec colnum="1" colname="col1" colwidth="15mm" /><colspec colnum="2" colname="col2" colwidth="26mm" /><colspec colnum="3" colname="col3" colwidth="27mm" /><colspec colnum="4" colname="col4" colwidth="24mm" /><colspec colnum="5" colname="col5" colwidth="26mm" /><colspec colnum="6" colname="col6" colwidth="27mm" /><thead><row><entry valign="top"><i>d_FROM</i></entry><entry valign="top"><i>ΔT_reply</i> = 20 ns</entry><entry valign="top"><i>ΔT_reply</i> = 200 ns</entry><entry valign="top"><i>ΔT_reply</i> = 2 µs</entry><entry valign="top"><i>ΔT_reply</i> = 20 µs</entry><entry valign="top"><i>ΔT_reply</i> = 200 µs</entry></row></thead><tbody><row><entry>10th cm</entry><entry>± 0.015 cm</entry><entry>± 0.15 cm</entry><entry>± 1.5 cm</entry><entry>± 15 cm</entry><entry>± 150 cm</entry></row><row><entry>1 m</entry><entry>± 0.015 cm</entry><entry>± 0.15 cm</entry><entry>± 1.5 cm</entry><entry>± 15 cm</entry><entry>± 150 cm</entry></row><row><entry>10th m</entry><entry>± 0.05 cm</entry><entry>± 0.15 cm</entry><entry>± 1.5 cm</entry><entry>± 15 cm</entry><entry>± 150 cm</entry></row><row><entry>100 m</entry><entry>± 0.5 cm</entry><entry>± 0.5 cm</entry><entry>± 1.5 cm</entry><entry>± 15 cm</entry><entry>± 150 cm</entry></row><row><entry>1 km</entry><entry>± 5 cm</entry><entry>± 5 cm</entry><entry>± 5 cm</entry><entry>± 15 cm</entry><entry>± 150 cm</entry></row><row><entry>10th km</entry><entry>± 50 cm</entry><entry>± 50 cm</entry><entry>± 50 cm</entry><entry>± 50 cm</entry><entry>± 150 cm</entry></row></tbody></tgroup></table></tables>

0163The table above shows that the inventive method up to the difference in the response time intervals <i>ΔT_reply</i> of 20 µs and a distance between the transceivers A and B of 10 km enables an amazingly accurate distance determination with an error caused by quartz tolerances of only ± 50 cm. However, even if there is a difference in the response time intervals<i>ΔT_reply</i> 200 µs and a distance between the transceivers A and B of 10 km or less achieved sufficient accuracy for many applications. For example, the accuracy of ± 150 cm is usually sufficient to determine in which room of a building a person is. If, for example, protocol regulations make it difficult to comply with the preferred difference of the response time intervals of 20 microseconds, clock generators with tighter tolerances can be used to increase the accuracy of the distance measurement, in which the relative time error values ​​(E_tA, E_tB) for example in the interval E_tA = -20..0..20 ppm and E_tB = -20..0..20 ppm. Such clock generators, however, are hardly more expensive considering the total cost of a transceiver system.

2nd n-way method

0164The following is based on the <figref idref="f0002">Figures 3 and 4</figref> as a second embodiment, a generalization of the 3-way method described above is described. In the n-way method described here, the distance between two transceivers is traversed by an odd number of n data frames.

0165First of all, the procedure is described. The accuracy of this n-way method is then derived mathematically.

2.1 Signal circuits in the n-way process

0166The n-way method essentially represents a generalization of the 3-way method described under 1.

0167A data frame 30 is emitted by a first transceiver A and received by a second transceiver B. This data frame is checked there and, after successful completion of the check, a second data frame 32 is sent to the first transceiver A with a response time interval.

0168The first transceiver A checks the second data frame 32 and sends a third data frame, likewise with a delay in a response time interval to the second transceiver B. Any number of data frame pairs can be transmitted to this sequence of data frames. Examples are in<figref idref="f0002">Figure 3</figref> data frames 34, 36, and 38 are shown. A total of n data frames are transmitted. Data frames 36 and 38 are n<figref idref="f0002">Fig. 3</figref> summarized by a curly bracket as a data frame pair 40 and drawn in dashed lines to symbolize that a multiple repetition of the transmission of such data frame pairs can take place within the scope of the present exemplary embodiment. The response time intervals<i>T_replyAk,</i> k = 2,4,6,8, ... (n-1) of <i>T_replyA2</i> to <i>T_{replyA (n-1),}</i> and <i>T_replyBi,</i> i = 1,3,5,7, .., (n-2) of <i>T_replyB1</i> to <i>T_{replyB (n-2)}</i> have a mean difference according to the formula <maths id="math0018" num=""><math display="block"><mrow><mi mathvariant="normal">Δ</mi><mo>⁢</mo><msub><mrow><mi>T</mi></mrow><mrow><mi>re</mi><mrow><mi mathvariant="italic">plyAVG</mi></mrow></mrow></msub><mo>=</mo><mfrac><mrow><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyA</mi><mo>⁢</mo><mn>2</mn></mrow></msub><mo>-</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyB</mi><mo>⁢</mo><mn>1</mn></mrow></msub><mo>+</mo><mn>..</mn><mo>+</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyA</mi><mo>⁢</mo><mfenced separators=""><mi>n</mi><mo>-</mo><mn>1</mn></mfenced></mrow></msub><mo>-</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyB</mi><mo>⁢</mo><mfenced separators=""><mi>n</mi><mo>-</mo><mn>2</mn></mfenced></mrow></msub></mrow><mrow><mfrac><mrow><mi>n</mi><mo>-</mo><mn>1</mn></mrow><mrow><mn>2</mn></mrow></mfrac></mrow></mfrac></mrow></math><img file="EP1815267B1_D0018.tif" /></maths> whose maximum amount is 20 microseconds. In a variant of this method, there are also the response time intervals<i>T_replyA2</i> and <i>T_replyB1</i> either identical or have a difference, the maximum amount of which is 20 microseconds.

0169The entire pulse transit time in the transmission medium is determined from the measurement of the round trip time of this message sequence, similar to the 3-way method

0170<figref idref="f0002">Figure 4</figref> shows in analog representation <figref idref="f0001">Figure 2</figref> the course of the procedure over time, showing only one pulse for each data frame.

0171The calculation of the arithmetic mean of the signal transit time T_prop is done using the following formula: <maths id="math0019" num=""><math display="block"><mrow><mtable columnalign="left"><mtr><mtd><msub><mrow><mi>T</mi></mrow><mrow><mrow><mi mathvariant="italic">prop</mi></mrow></mrow></msub><mo>=</mo><mfrac><mrow><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">roundA</mi><mo>⁢</mo><mn>1</mn></mrow></msub><mo>-</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyB</mi><mo>⁢</mo><mn>1</mn></mrow></msub><mo>+</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">roundB</mi><mo>⁢</mo><mn>2</mn></mrow></msub><mo>-</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyA</mi><mo>⁢</mo><mn>2</mn></mrow></msub><mo>+</mo><mn>..</mn><mo>+</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">roundA</mi><mo>⁢</mo><mfenced separators=""><mi>n</mi><mo>-</mo><mn>2</mn></mfenced></mrow></msub><mo>-</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyB</mi><mo>⁢</mo><mfenced separators=""><mi>n</mi><mo>-</mo><mn>2</mn></mfenced></mrow></msub><mo>+</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">roundB</mi><mo>⁢</mo><mfenced separators=""><mi>n</mi><mo>-</mo><mn>1</mn></mfenced></mrow></msub><mo>+</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyA</mi><mo>⁢</mo><mfenced separators=""><mi>n</mi><mo>-</mo><mn>1</mn></mfenced></mrow></msub></mrow><mrow><mn>2</mn><mo>⁢</mo><mfenced separators=""><mi>n</mi><mo>-</mo><mn>1</mn></mfenced></mrow></mfrac></mtd></mtr><mtr><mtd><mi>n</mi><mo>=</mo><mn>2</mn><mo>⁢</mo><mi>k</mi><mo>+</mo><mn>1</mn><mo>,</mo><mi>k</mi><mo>∈</mo><mi>N</mi><mo>></mo><mn>1</mn></mtd></mtr></mtable></mrow></math><img file="EP1815267B1_D0019.tif" /></maths>

0172From the signal runtime <b><i>T_prop</i></b> the distance can be calculated again.

0173Since the total round trip time T_round If the n-way method is also not measured directly, the directly measured partial concentricity intervals (T_roundA1, T_roundB2, .., T_{roundA (n-2)}, T_{roundB (n-1)}) used. The response times (T_replyA2, T_replyB1, ..., T_{replyA (n-1)}, T_{replyB (n-2)}) Both transceivers must be known.

2.2 Accuracy of the n-way method

0174If the sum of the differences in the response times (T_replyA2, T_replyB1, ..., T_{replyA (n-1)}, T_{replyB (n-2)}) according to the invention kept very small or is zero (<i>T_replyA2</i>-<i>T_replyB1</i>+..+<i>T</i>_{<i>replyA</i>(<i>n</i>-1)}-<i>T</i>_{<i>reply</i>(<i>n</i>-2)}→ 0), this symmetrical n-way method as with the 3-way method described above achieves the advantage of an unexpectedly high accuracy of the distance measurement. This is explained in more detail below.

0175The relative time errors on the part of the transceivers A and B already explained above under 1.2 results in the relative error E for the determined pulse transit time or the distance calculated therefrom_tab according to formula 16: <maths id="math0020" num="Formel 16:"><math display="block"><mrow><msub><mi mathvariant="italic">T</mi><mi mathvariant="italic">prop</mi></msub><mo>⁢</mo><mfenced separators=""><mn>1</mn><mo>+</mo><msub><mi>E</mi><mi mathvariant="italic">tab</mi></msub></mfenced><mo>=</mo><mfrac><mrow><mrow><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">roundA</mi><mo>⁢</mo><mn>1</mn></mrow></msub><mo>⁢</mo><mi>ʹ</mi><mo>-</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyB</mi><mo>⁢</mo><mn>1</mn></mrow></msub><mo>⁢</mo><mi>ʹ</mi><mo>+</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">roundB</mi><mo>⁢</mo><mn>2</mn></mrow></msub><mo>⁢</mo><mi>ʹ</mi><mo>-</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyA</mi><mo>⁢</mo><mn>2</mn></mrow></msub><mo>⁢</mo><mi>ʹ</mi><mo>+</mo><mn>..</mn><mo>+</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">round</mi><mo>⁢</mo><mfenced separators=""><mi>n</mi><mo>-</mo><mn>2</mn></mfenced></mrow></msub><mo>⁢</mo><mi>ʹ</mi><mo>-</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyB</mi><mo>⁢</mo><mfenced separators=""><mi>n</mi><mo>-</mo><mn>2</mn></mfenced></mrow></msub><mo>⁢</mo><mi>ʹ</mi><mo>+</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">roundB</mi><mo>⁢</mo><mfenced separators=""><mi>n</mi><mo>-</mo><mn>1</mn></mfenced></mrow></msub><mo>⁢</mo><mi>ʹ</mi><mo>-</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyA</mi><mo>⁢</mo><mfenced separators=""><mi>n</mi><mo>-</mo><mn>1</mn></mfenced></mrow></msub><mo>⁢</mo><mi>ʹ</mi></mrow></mrow><mrow><mn>2</mn><mo>⁢</mo><mfenced separators=""><mi>n</mi><mo>-</mo><mn>1</mn></mfenced></mrow></mfrac></mrow></math><img file="EP1815267B1_D0020.tif" /></maths>

0176Taking into account the error E_tA and E_tB according to formula 17 to formula 20 <maths id="math0021" num="Formel 17:"><math display="block"><mrow><msub><mi>T</mi><mi mathvariant="italic">roundAn</mi></msub><mo>⁢</mo><mi>ʹ</mi><mo>=</mo><msub><mi>T</mi><mi mathvariant="italic">roundAn</mi></msub><mo>⁢</mo><mfenced separators=""><mn>1</mn><mo>+</mo><msub><mi>E</mi><mi mathvariant="italic">tA</mi></msub></mfenced><mo>,</mo><mrow><mspace width="2em" /></mrow><mi>n</mi><mo>=</mo><mn>2</mn><mo>⁢</mo><mi>k</mi><mo>+</mo><mn>1</mn><mo>,</mo><mrow><mspace width="2em" /></mrow><mi>k</mi><mo>∈</mo><mi>N</mi></mrow></math><img file="EP1815267B1_D0021.tif" /></maths><maths id="math0022" num="Formel 18:"><math display="block"><mrow><msub><mi>T</mi><mi mathvariant="italic">replyAn</mi></msub><mo>⁢</mo><mi>ʹ</mi><mo>=</mo><msub><mi>T</mi><mi mathvariant="italic">replyAn</mi></msub><mo>⁢</mo><mfenced separators=""><mn>1</mn><mo>+</mo><msub><mi>E</mi><mi mathvariant="italic">tA</mi></msub></mfenced><mo>,</mo><mrow><mspace width="2em" /></mrow><mi>n</mi><mo>=</mo><mn>2</mn><mo>⁢</mo><mi>k</mi><mo>,</mo><mrow><mspace width="2em" /></mrow><mi>k</mi><mo>∈</mo><mi>N</mi><mo>></mo><mn>0</mn></mrow></math><img file="EP1815267B1_D0022.tif" /></maths><maths id="math0023" num="Formel 19:"><math display="block"><mrow><msub><mi>T</mi><mi mathvariant="italic">roundBn</mi></msub><mo>⁢</mo><mi>ʹ</mi><mo>=</mo><msub><mi>T</mi><mi mathvariant="italic">roundBn</mi></msub><mo>⁢</mo><mfenced separators=""><mn>1</mn><mo>+</mo><msub><mi>E</mi><mi mathvariant="italic">tB</mi></msub></mfenced><mo>,</mo><mrow><mspace width="2em" /></mrow><mi>n</mi><mo>=</mo><mn>2</mn><mo>⁢</mo><mi>k</mi><mo>,</mo><mrow><mspace width="2em" /></mrow><mi>k</mi><mo>∈</mo><mi>N</mi><mo>></mo><mn>0</mn></mrow></math><img file="EP1815267B1_D0023.tif" /></maths><maths id="math0024" num="Formel 20:"><math display="block"><mrow><msub><mi>T</mi><mi mathvariant="italic">replyBn</mi></msub><mo>⁢</mo><mi>ʹ</mi><mo>=</mo><msub><mi>T</mi><mi mathvariant="italic">replyBn</mi></msub><mo>⁢</mo><mfenced separators=""><mn>1</mn><mo>+</mo><msub><mi>E</mi><mi mathvariant="italic">tB</mi></msub></mfenced><mo>,</mo><mrow><mspace width="2em" /></mrow><mi>n</mi><mo>=</mo><mn>2</mn><mo>⁢</mo><mi>k</mi><mo>+</mo><mn>1</mn><mo>,</mo><mrow><mspace width="2em" /></mrow><mi>k</mi><mo>∈</mo><mi>N</mi></mrow></math><img file="EP1815267B1_D0024.tif" /></maths> the error of the signal transit time or the distance can be determined: <maths id="math0025" num="Formel 21:"><math display="block"><mrow><msub><mi>E</mi><mi mathvariant="italic">tab</mi></msub><mo>=</mo><msub><mrow><mi>½</mi><mrow><mi>E</mi></mrow></mrow><mrow><mi mathvariant="italic">tA</mi></mrow></msub><mo>+</mo><msub><mrow><mi>½</mi><mrow><mi>E</mi></mrow></mrow><mrow><mi mathvariant="italic">tB</mi></mrow></msub><mo>+</mo><mfrac><mrow><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyA</mi><mo>⁢</mo><mn>2</mn></mrow></msub><mo>-</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyB</mi><mo>⁢</mo><mn>1</mn></mrow></msub><mo>+</mo><mn>..</mn><mo>+</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyA</mi><mo>⁢</mo><mfenced separators=""><mi>n</mi><mo>-</mo><mn>1</mn></mfenced></mrow></msub><mo>-</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyB</mi><mo>⁢</mo><mfenced separators=""><mi>n</mi><mo>-</mo><mn>2</mn></mfenced></mrow></msub></mrow><mrow><mn>2</mn><mo>⁢</mo><mfenced separators=""><mi>n</mi><mo>-</mo><mn>1</mn></mfenced><mo>⁢</mo><msub><mi>T</mi><mi mathvariant="italic">prop</mi></msub></mrow></mfrac><mo>⁢</mo><mfenced separators=""><msub><mi>E</mi><mi mathvariant="italic">tB</mi></msub><mo>-</mo><msub><mi>E</mi><mi mathvariant="italic">tA</mi></msub></mfenced></mrow></math><img file="EP1815267B1_D0025.tif" /></maths>

0177The sum of the response time differences <maths id="math0026" num=""><math display="block"><mrow><mfenced separators=""><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyA</mi><mo>⁢</mo><mn>2</mn></mrow></msub><mo>-</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyB</mi><mo>⁢</mo><mn>1</mn></mrow></msub><mo>+</mo><mn>..</mn><mo>+</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyA</mi><mo>⁢</mo><mfenced separators=""><mi>n</mi><mo>-</mo><mn>1</mn></mfenced></mrow></msub><mo>-</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyB</mi><mo>⁢</mo><mfenced separators=""><mi>n</mi><mo>-</mo><mn>2</mn></mfenced></mrow></msub><mo>=</mo><mrow><mo>∑</mo><mi mathvariant="normal">Δ</mi></mrow><msub><mi>T</mi><mi mathvariant="italic">reply</mi></msub></mfenced></mrow></math><img file="EP1815267B1_D0026.tif" /></maths> divided by their number <maths id="math0027" num=""><math display="inline"><mrow><mfenced><mfrac><mrow><mi>n</mi><mo>-</mo><mn>1</mn></mrow><mrow><mn>2</mn></mrow></mfrac></mfenced></mrow></math><img file="EP1815267B1_D0027.tif" /></maths> an average Δ<i>T_replyAVG</i> for response times according to Formula 22 below: <maths id="math0028" num="Formel 22:"><math display="block"><mrow><mfrac><mrow><mrow><mo>∑</mo><mi mathvariant="normal">Δ</mi></mrow><msub><mi>T</mi><mi mathvariant="italic">reply</mi></msub></mrow><mrow><mfrac><mrow><mi>n</mi><mo>-</mo><mn>1</mn></mrow><mrow><mn>2</mn></mrow></mfrac></mrow></mfrac><mo>=</mo><mrow><mi mathvariant="normal">Δ</mi></mrow><msub><mi>T</mi><mi mathvariant="italic">replyAVG</mi></msub></mrow></math><img file="EP1815267B1_D0028.tif" /></maths>

0178In this way, the error of the signal transit time can be represented in a simplified manner as follows (formula 23) <maths id="math0029" num="Formel 23:"><math display="block"><mrow><msub><mi>E</mi><mi mathvariant="italic">tab</mi></msub><mo>=</mo><msub><mrow><mi>½</mi><mrow><mi>E</mi></mrow></mrow><mrow><mi mathvariant="italic">tA</mi></mrow></msub><mo>+</mo><msub><mrow><mi>½</mi><mrow><mi>E</mi></mrow></mrow><mrow><mi mathvariant="italic">tB</mi></mrow></msub><mo>+</mo><mfrac><mrow><mrow><mi mathvariant="normal">Δ</mi></mrow><msub><mi>T</mi><mi mathvariant="italic">replyAVG</mi></msub></mrow><mrow><mn>4</mn><mo>⁢</mo><msub><mi>T</mi><mi mathvariant="italic">prop</mi></msub></mrow></mfrac><mo>⁢</mo><mfenced separators=""><msub><mi>E</mi><mi mathvariant="italic">tB</mi></msub><mo>-</mo><msub><mi>E</mi><mi mathvariant="italic">tA</mi></msub></mfenced></mrow></math><img file="EP1815267B1_D0029.tif" /></maths>

0179Two cases of time errors are again considered to estimate the error properties. Identical to the 3-way method, the relative error of the distance corresponds to the arithmetic mean of the relative errors E_tA and E_tB (see formula 13) if both errors are equal (E_tA = E_tB). Similar to the 3-way method, errors of the same amount with different signs (E_tA = - E_tB) the error essentially depends on the ratio of the mean value of the response time differences to the four times the signal transit time according to formula 24: <maths id="math0030" num="Formel 24:"><math display="block"><mrow><msub><mi>E</mi><mi mathvariant="italic">tab</mi></msub><mo>=</mo><mfrac><mrow><mrow><mi mathvariant="normal">Δ</mi></mrow><msub><mi>T</mi><mi mathvariant="italic">replyAVG</mi></msub></mrow><mrow><mn>4</mn><mo>⁢</mo><msub><mi>T</mi><mi mathvariant="italic">prop</mi></msub></mrow></mfrac><mo>⁢</mo><mfenced separators=""><msub><mi>E</mi><mi mathvariant="italic">tB</mi></msub><mo>-</mo><msub><mi>E</mi><mi mathvariant="italic">tA</mi></msub></mfenced></mrow></math><img file="EP1815267B1_D0030.tif" /></maths>

0180The precision of the distance measurement in the n-way method compared to the 3-way method is also independent of the absolute concentricity and response time intervals. The error becomes smaller as the distance increases.

0181In practical implementations of transceivers, the response time differences can, as already mentioned, be kept very small, but often cannot be avoided due to scanning errors in the digital system components. However, if the response times in an n-way measurement are evenly varied or scattered, the mean value of the response time differences becomes very small (Δ<i>_TreplyAVG</i> → 0), since negative differences can also occur. In practical implementations, this is approximated in that the scanning errors occur randomly. The average of the differences in the response time intervals tends to be significantly smaller than the difference in response time intervals in the 3-way process:<maths id="math0031" num=""><math display="block"><mrow><mrow><mi mathvariant="normal">Δ</mi></mrow><msub><mi>T</mi><mi mathvariant="italic">replyAVG</mi></msub><mo>&lt;</mo><mfenced open="|" close="|" separators=""><msub><mi>T</mi><mi mathvariant="italic">replyA</mi></msub><mo>-</mo><msub><mi>T</mi><mi mathvariant="italic">replyB</mi></msub></mfenced><mn>.</mn></mrow></math><img file="EP1815267B1_D0031.tif" /></maths> (compare formula and formula 23). The relative error of the distance is thus smaller than in the 3-way method, and the n-way method also proves to be accurate for the distance measurement.

3rd Double-sided two-way process

0182Based on <figref idref="f0003">Figures 5 and 6</figref> a double-sided two-way method is described below as the third exemplary embodiment of the method according to the invention for determining the distance.

3.1 Signal circuits in the double-sided two-way process

0183To carry out a first signal round-trip, a first data frame 42 is transmitted by a first transmitter-receiver A and received by a second transmitter-receiver B in the form of a received data frame 42 '.

0184This received data frame 42 'is checked by the transceiver 42 and, if successful, with a response time interval for receiving the first data frame 42', a first subsequent data frame in the form of a second data frame 44 is sent to the first transceiver A. The reception of the second data frame 44 at the first transceiver A in the form of a reception signal 44 ′ completes the first signal round trip.

0185To carry out a second signal round, the second transceiver B sends a third data frame 46 to the first transceiver A, which in turn checks the received third data frame 46 'and a second subsequent data frame in the form of a fourth data frame 48 with a response time interval for receiving the third data frame 46' second transceiver (B) sends. The reception of the fourth data frame 48 sent out at the second transceiver B in the form of a reception signal 48 ′ completes the second signal round.

0186The method is carried out in such a way that the response time intervals T_replyA2 and T_replyB1 on the part of the first and second transceivers are either identical or have a difference, the maximum amount of which is 20 microseconds.

0187This two-way message exchange, which was started once by both transceivers and is used to determine the distance in two different signal circuits, is referred to as a two-sided two-way process. The two signal rounds can be carried out in succession in the same transmission channel, or the exchange can take place at the same time or overlapping when using two separate message channels.

0188The pulse transit times in the transmission medium are determined from the measurements of the round trip intervals of the message sequences after deduction of the known response times.

0189The respective pulse transit times are calculated as follows (see Formula 25 and Formula 26): <maths id="math0032" num="Formel 25:"><math display="block"><mrow><msub><mrow><mi>T</mi></mrow><mrow><mrow><mi mathvariant="italic">propA</mi></mrow></mrow></msub><mo>=</mo><mfrac><mrow><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">roundA</mi><mo>⁢</mo><mn>1</mn></mrow></msub><mo>-</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyB</mi><mo>⁢</mo><mn>1</mn></mrow></msub></mrow><mrow><mn>2</mn></mrow></mfrac></mrow></math><img file="EP1815267B1_D0032.tif" /></maths><maths id="math0033" num="Formel 26:"><math display="block"><mrow><msub><mrow><mi>T</mi></mrow><mrow><mrow><mi mathvariant="italic">propB</mi></mrow></mrow></msub><mo>=</mo><mfrac><mrow><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">roundB</mi><mo>⁢</mo><mn>2</mn></mrow></msub><mo>-</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyA</mi><mo>⁢</mo><mn>2</mn></mrow></msub></mrow><mrow><mn>2</mn></mrow></mfrac></mrow></math><img file="EP1815267B1_D0033.tif" /></maths>

0190The calculated pulse transit times (T_propA, T_propB) are then averaged (see formula 27) and the distance is then calculated from the averaged pulse duration. <maths id="math0034" num="Formel 27:"><math display="block"><mrow><msub><mrow><mi>T</mi></mrow><mrow><mrow><mi mathvariant="italic">prop</mi></mrow></mrow></msub><mo>=</mo><mfrac><mrow><msub><mi>T</mi><mi mathvariant="italic">propA</mi></msub><mo>+</mo><msub><mi>T</mi><mi mathvariant="italic">propB</mi></msub></mrow><mrow><mn>2</mn></mrow></mfrac></mrow></math><img file="EP1815267B1_D0034.tif" /></maths>

0191The calculation can be summarized as follows by using Formula 25 and Formula 26 in Formula 27 (see Formula 28). <maths id="math0035" num="Formel 28:"><math display="block"><mrow><msub><mrow><mi>T</mi></mrow><mrow><mrow><mi mathvariant="italic">prop</mi></mrow></mrow></msub><mo>=</mo><mfrac><mrow><msub><mi>T</mi><mi mathvariant="italic">roundA</mi></msub><mo>-</mo><msub><mi>T</mi><mi mathvariant="italic">replyB</mi></msub><mo>+</mo><msub><mi>T</mi><mi mathvariant="italic">roundB</mi></msub><mo>-</mo><msub><mi>T</mi><mi mathvariant="italic">replyA</mi></msub></mrow><mrow><mn>4</mn></mrow></mfrac></mrow></math><img file="EP1815267B1_D0035.tif" /></maths>

0192The calculation according to this formula 28 is therefore identical to the 3-way method. In the same way as there, the spatial distance between the two transceivers A and B can be calculated from the pulse transit time.

3.2 Accuracy of the double-sided two-way process

0193Since the calculation of the pulse transit time of the double-sided two-way process is identical to the 3-way process (compare formula 28), and the errors can be taken into account in the same way as with the 3-way process (formula 8 to formula 11) , the same function for the relative error of the pulse duration or distance results as for the 3-way method (see formula 12). The double-sided two-way process can thus be used as an alternative to the 3-way process with identical error properties, which is the essential feature of this process

4th Multi-sided, two-way process

0194The following is based on the <figref idref="f0004">Figures 7 and 8</figref> describes a fourth exemplary embodiment of the method according to the invention, in which repetition of signal concentricity pairs and a multiple, double-sided, two-way method is carried out.

4.1 Signal circuits

0195At the beginning of a first signal round 50, a first data frame 52 is transmitted by a first transceiver A and received by a second transceiver B. This received data frame 52 'is checked there and, if successful, a subsequent data frame in the form of a second data frame 54 with a response time interval T_replyB1 sent to the first transceiver A to receive the first data frame 52 '. The reception of the second data frame 54 at the first transceiver A ends the first signal round 50.

0196At the start of a second signal round 56, the second transceiver B sends a third data frame 58 to the first transceiver A. This received data frame 58 'is checked there and, if successful, a subsequent data frame in the form of a fourth data frame 60 with a response time interval T._replyA2 to receive the third data frame 58 'sent to the second transceiver B. The reception of the fourth data frame 60 at the second transceiver B ends the second signal round 56.

0197The two-way two-way message exchange described so far is carried out a total of n-1 times. The procedure is carried out so that the response time intervals<b><i>T_replyAk</i>,</b> k = 2,4,6,8. ,, (n-1) of <b><i>T_replyA2</i></b> to <b><i>T</i>_{<i>replyA (n-1</i>)}<i>,</i></b> and <b><i>T_replyBi</i>,</b> i = 1,3,5,7 .., (n-2) of <b><i>T_replyB1</i></b> to <b><i>T</i>_{<i>replyB</i>(<i>n-2)</i>}</b> occur that have a mean difference according to the formula <maths id="math0036" num=""><math display="block"><mrow><mi mathvariant="normal">Δ</mi><mo>⁢</mo><msub><mrow><mi>T</mi></mrow><mrow><mi>re</mi><mrow><mi mathvariant="italic">plyAVG</mi></mrow></mrow></msub><mo>=</mo><mfrac><mrow><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyA</mi><mo>⁢</mo><mn>2</mn></mrow></msub><mo>-</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyB</mi><mo>⁢</mo><mn>1</mn></mrow></msub><mo>+</mo><mn>..</mn><mo>+</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyA</mi><mo>⁢</mo><mfenced separators=""><mi>n</mi><mo>-</mo><mn>1</mn></mfenced></mrow></msub><mo>-</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyB</mi><mo>⁢</mo><mfenced separators=""><mi>n</mi><mo>-</mo><mn>2</mn></mfenced></mrow></msub></mrow><mrow><mfrac><mrow><mi>n</mi><mo>-</mo><mn>1</mn></mrow><mrow><mn>2</mn></mrow></mfrac></mrow></mfrac></mrow></math><img file="EP1815267B1_D0036.tif" /></maths> exhibit.

0198The signal rounds can take place in succession in the same transmission channel. Alternatively, when using two or more separate message channels, two or more signal round trips can be carried out simultaneously or overlapping in time. In the sequential variant, the direction of the two-way message sequences is not tied to a specific order. The individual message sequences are independent of one another.

0199The pulse transit times from both sides (see formula 29 and formula 30) are calculated from the respective measured round time intervals and the known response time intervals. <maths id="math0037" num="Formel 29:"><math display="block"><mrow><msub><mi>T</mi><mi mathvariant="italic">propAx</mi></msub><mo>=</mo><mfrac><mrow><mrow><msub><mi>T</mi><mi mathvariant="italic">roundAx</mi></msub><mo>-</mo><msub><mi>T</mi><mi mathvariant="italic">replyBx</mi></msub></mrow></mrow><mrow><mn>2</mn></mrow></mfrac><mo>,</mo><mrow><mspace width="2em" /></mrow><mi>x</mi><mo>=</mo><mn>2</mn><mo>⁢</mo><mi>k</mi><mo>+</mo><mn>1</mn><mo>,</mo><mrow><mspace width="2em" /></mrow><mi>x</mi><mo><</mo><mi>n</mi><mo>,</mo><mrow><mspace width="2em" /></mrow><mi>k</mi><mo>∈</mo><mi>N</mi></mrow></math><img file="EP1815267B1_D0037.tif" /></maths><maths id="math0038" num="Formel 30:"><math display="block"><mrow><msub><mrow><mi>T</mi></mrow><mrow><mrow><mi mathvariant="italic">propBy</mi></mrow></mrow></msub><mo>=</mo><mfrac><mrow><msub><mrow><mi>T</mi></mrow><mrow><mrow><mi mathvariant="italic">roundBy</mi></mrow></mrow></msub><mo>-</mo><msub><mrow><mi>T</mi></mrow><mrow><mrow><mi mathvariant="italic">replyA</mi></mrow><mi>y</mi></mrow></msub></mrow><mrow><mn>2</mn></mrow></mfrac><mo>,</mo><mrow><mspace width="2em" /></mrow><mi>y</mi><mo>=</mo><mn>2</mn><mo>⁢</mo><mi>k</mi><mo>,</mo><mrow><mspace width="2em" /></mrow><mi>x</mi><mo><</mo><mi>n</mi><mo>,</mo><mrow><mspace width="2em" /></mrow><mi>k</mi><mo>∈</mo><mi>N</mi><mo>></mo><mn>0</mn></mrow></math><img file="EP1815267B1_D0038.tif" /></maths>

0200The impulse running times (<i>T</i>_{<i>propAx</i>,}<i>T_propBy</i>) are then averaged (see formula 31) and the distance is then calculated from the averaged pulse duration. <maths id="math0039" num="Formel 31:"><math display="block"><mrow><msub><mrow><mi>T</mi></mrow><mrow><mrow><mi mathvariant="italic">prop</mi></mrow></mrow></msub><mo>=</mo><mfrac><mrow><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">propA</mi><mo>⁢</mo><mn>1</mn></mrow></msub><mo>-</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">propB</mi><mo>⁢</mo><mn>2</mn></mrow></msub><mo>+</mo><mn>..</mn><mo>+</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">propA</mi><mo>⁢</mo><mfenced separators=""><mi>n</mi><mo>-</mo><mn>2</mn></mfenced></mrow></msub><mo>+</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">propB</mi><mo>⁢</mo><mfenced separators=""><mi>n</mi><mo>-</mo><mn>1</mn></mfenced></mrow></msub></mrow><mrow><mfenced separators=""><mi>n</mi><mo>-</mo><mn>1</mn></mfenced></mrow></mfrac></mrow></math><img file="EP1815267B1_D0039.tif" /></maths>

0201The calculation can be summarized as follows by inserting Formula 29 and Formula 30 into Formula 31 (see Formula 32). <maths id="math0040" num="Formel 32*:"><math display="block"><mrow><mtable columnalign="left"><mtr><mtd><msub><mrow><mi>T</mi></mrow><mrow><mrow><mi mathvariant="italic">prop</mi></mrow></mrow></msub><mo>=</mo><mfrac><mrow><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">roundA</mi><mo>⁢</mo><mn>1</mn></mrow></msub><mo>-</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyB</mi><mo>⁢</mo><mn>1</mn></mrow></msub><mo>+</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">roundB</mi><mo>⁢</mo><mn>2</mn></mrow></msub><mo>-</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyA</mi><mo>⁢</mo><mn>2</mn></mrow></msub><mo>+</mo><mn>..</mn><mo>+</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">roundA</mi><mo>⁢</mo><mfenced separators=""><mi>n</mi><mo>-</mo><mn>2</mn></mfenced></mrow></msub><mo>-</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyB</mi><mo>⁢</mo><mfenced separators=""><mi>n</mi><mo>-</mo><mn>2</mn></mfenced></mrow></msub><mo>+</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">roundB</mi><mo>⁢</mo><mfenced separators=""><mi>n</mi><mo>-</mo><mn>1</mn></mfenced></mrow></msub><mo>-</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyA</mi><mo>⁢</mo><mfenced separators=""><mi>n</mi><mo>-</mo><mn>1</mn></mfenced></mrow></msub></mrow><mrow><mn>2</mn><mo>⁢</mo><mfenced separators=""><mi>n</mi><mo>-</mo><mn>1</mn></mfenced></mrow></mfrac></mtd></mtr><mtr><mtd><mi>n</mi><mo>=</mo><mn>2</mn><mo>⁢</mo><mi>k</mi><mo>+</mo><mn>1</mn><mo>,</mo><mi>k</mi><mo>∈</mo><mi>N</mi><mo>></mo><mn>1</mn></mtd></mtr></mtable></mrow></math><img file="EP1815267B1_D0040.tif" /></maths>

0202The calculation is thus identical to the n-way method described above, a special case of which is the 3-way method described above

0203Since the sum of the differences in response times (T_replyA2, T_replyB1, ..., T_{replyA (n-1)}, T_{replyB (n-2)}) is kept very small or completely disappears in the course of the process according to the invention (<i>T_replyA2</i>-<i>T_replyB1</i>+..+<i>T</i>_{<i>replyA</i>(<i>n-</i>1)}-<i>T</i>_{<i>reply</i>(<i>n</i>-2)} → 0) one can speak of a symmetrical multi-sided two-way process.

4.2 Accuracy of the multi-sided two-way process

0204Since the calculation of the pulse transit time of the multi-sided two-way method is identical to the n-way method (compare formula 32 and formula 15), and the errors can be taken into account in the same way as with the n-way method (Formula 17 to Formula 20), the relative error of the pulse duration or distance results in the same function as with the n-way method (see Formula 22). The multiple-sided two-way method can thus be used as a replacement for the n-way method with identical error properties, which is the essential feature of this method.

5. Dithering and avering

0205In the following, the fifth exemplary embodiment of the method according to the invention is shown in FIG <figref idref="f0005 f0006 f0007 f0008">Figures 9 to 13</figref> describes a method that can be applied to all the exemplary embodiments described above, with which the accuracy of the distance determination can be further increased.

0206The capacity C of a transmission channel, ie the amount of information that can be transmitted in a certain time, is determined by Shannon's theorem of channel capacity (see formula 33). <maths id="math0041" num="Formel 33:"><math display="block"><mrow><mi>C.</mi><mo>=</mo><mi>B</mi><mrow><msub><mrow><mi>log</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>⁢</mo><mfenced separators=""><mn>1</mn><mo>+</mo><mi mathvariant="italic">SNR</mi></mfenced></mrow></mrow></math><img file="EP1815267B1_D0041.tif" /></maths>

0207B denotes the bandwidth of the channel and SNR the signal-to-noise ratio. This can be done in a certain time<i>T</i> the amount of information / transferred (see Formula 34). <maths id="math0042" num="Formel 34:"><math display="block"><mrow><mi>I.</mi><mo>=</mo><mi mathvariant="italic">BT</mi><mrow><msub><mrow><mi>log</mi></mrow><mrow><mn>2</mn></mrow></msub></mrow><mfenced separators=""><mn>1</mn><mo>+</mo><mi mathvariant="italic">SNR</mi></mfenced></mrow></math><img file="EP1815267B1_D0042.tif" /></maths>

0208The accuracy of a value of a quantity that is transmitted as information is proportional to the amount of information that is available for the transmission of the value, for example in the form of available decimal places. Since the available bandwidth B and output power, which determine the signal-to-noise ratio SNR, are limited for various reasons, for example due to legal regulations, the amount of information can only be increased by increasing the duration of the transmission T, see. Formula 34. It is therefore obvious to use the arrival times of as many impulses as possible as a basis for the exact determination of the arrival time (ToA = Time of Arrival) of a data frame and thus to increase the amount of information.

0209Regarding <figref idref="f0005">Fig. 9</figref> a data frame a to be sent consists of a sequence of pulses a1, a2, a3 to an with a known pulse frequency, which occurs in a known pulse period T._i reflects.

0210In the dithering carried out in the present exemplary embodiment, however, the pulse periods are not constant. Individual pulses b1 to bn of a data frame b transmitted according to the dithering method each have a time deviation ΔT_ijon, j = 1, 2, ..., n ,.

0211Ideally, the deviations are ΔT_ij completely evenly distributed, and the sum of the deviations is zero: <maths id="math0043" num="Formel 35:"><math display="block"><mrow><mi mathvariant="normal">Δ</mi><mrow><msub><mrow><mi>T</mi></mrow><mrow><mi>i</mi><mo>⁢</mo><mn>1</mn></mrow></msub></mrow><mo>+</mo><mi mathvariant="normal">Δ</mi><mrow><msub><mrow><mi>T</mi></mrow><mrow><mi>i</mi><mo>⁢</mo><mn>2</mn></mrow></msub></mrow><mo>+</mo><mi mathvariant="normal">Δ</mi><mrow><msub><mrow><mi>T</mi></mrow><mrow><mi>i</mi><mo>⁢</mo><mn>3</mn></mrow></msub></mrow><mo>+</mo><mn>..</mn><mo>+</mo><mi mathvariant="normal">Δ</mi><mrow><msub><mi>T</mi><mi mathvariant="italic">in</mi></msub></mrow><mo>→</mo><mn>0</mn></mrow></math><img file="EP1815267B1_D0043.tif" /></maths>

0212The following is based on <figref idref="f0005">Fig. 10</figref> describes an averaging carried out in combination with dithering. In averaging, differences in arrival times are ΔT_iRXi individual received pulses b1 ', b2' to bn 'are measured relative to the nearest raster points of a fixed time raster R. The grid R corresponds to the pulse period T_i and has a fixed reference (synchronous) to the time grid (clock generator) of the receiving device of a transceiver.

0213Any detected pulse of the data frame is assigned to the grid as a reference point (tToA '), and the grid is adjusted as precisely as possible to the pulse sequence once per data frame. The achievable accuracy of the adjustment depends on the time grid / clock generator of the receiving device.

0214Since the deviations in the context of dithering are much smaller than the pulse period T_i are dimensioned, a clear assignment of the raster points to the detected pulses is guaranteed. The measurements of the deviations (ΔT_iRXi) are accumulated and then arithmetically averaged see formula 36). Since in dithering the sum of all deviations ideally results in zero, the mean value corresponds to Δ<i>T</i>_{<i>iR</i>XAVG} the difference in the exact arrival time of the data frame (<i>t_ToA</i>) to the reference point (<i>t_ToA</i>'). <maths id="math0044" num="Formel 36:"><math display="block"><mrow><mi mathvariant="normal">Δ</mi><mo>⁢</mo><msub><mi>T</mi><mi mathvariant="italic">iRXAVG</mi></msub><mo>=</mo><mfrac><mrow><mi mathvariant="normal">Δ</mi><mo>⁢</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">iRX</mi><mo>⁢</mo><mn>1</mn></mrow></msub><mo>+</mo><mi mathvariant="normal">Δ</mi><mo>⁢</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">iRX</mi><mo>⁢</mo><mn>2</mn></mrow></msub><mo>+</mo><mn>..</mn><mo>+</mo><mi mathvariant="normal">Δ</mi><mo>⁢</mo><msub><mi>T</mi><mi mathvariant="italic">iRXn</mi></msub></mrow><mrow><mi>n</mi></mrow></mfrac></mrow></math><img file="EP1815267B1_D0044.tif" /></maths><maths id="math0045" num="Formel 37:"><math display="block"><mrow><msub><mi mathvariant="italic">t</mi><mi mathvariant="italic">ToA</mi></msub><mo>=</mo><msub><mi mathvariant="italic">t</mi><mi mathvariant="italic">TOA</mi></msub><mo>⁢</mo><mi>ʹ</mi><mo>-</mo><mi mathvariant="normal">Δ</mi><mo>⁢</mo><msub><mi>T</mi><mi mathvariant="italic">iRXAVG</mi></msub></mrow></math><img file="EP1815267B1_D0045.tif" /></maths>

0215The additional method features described below are particularly suitable when using a dithering and averaging method in connection with the method of the invention:<ol id="ol0003" ol-style=""><li>a) Since the deviations inserted on the transmitter side determine the available pulse duration and there should be little loss of bandwidth with this method, the deviations at the transmitter set amount to only a small fraction of the pulse period.</li><li>b) Dithering can be inserted when sending, receiving or in both processes at the same time. The latter variant contributes in particular to the simple improvement of the uniform distribution of the dithering. Evenly distributed noise in the transmission link as well as the transmitter and receiver circuit is conducive to the method, since it improves the uniform distribution of the dithering.</li><li>c) The difference between the largest positive and negative deviation must be larger, i.e. the measurement resolution on the receiver side, in order to achieve a distribution over at least two different quantization levels (measurement resolution). The most efficient solution is therefore dithering, in which the difference between the deviations is greater than the measurement resolution<i>T_r</i> on the receiver side (see formula 38), but much smaller than the pulse period <i>T_i</i>. <maths id="math0046" num="Formel 38:"><math display="block"><mrow><msub><mi>T</mi><mi>r</mi></msub><mo>&lt;</mo><mi mathvariant="normal">Δ</mi><mo>⁢</mo><msub><mrow><mi>T</mi></mrow><mrow><msub><mi>i</mi><mi>Max</mi></msub></mrow></msub><mo>-</mo><mi mathvariant="normal">Δ</mi><mo>⁢</mo><msub><mrow><mi>T</mi></mrow><mrow><msub><mi>i</mi><mi>min</mi></msub></mrow></msub><mo>&lt;</mo><mo>&lt;</mo><msub><mi>T</mi><mi>i</mi></msub></mrow></math><img file="EP1815267B1_D0046.tif" /></maths></li><li>d) Furthermore, all pulses or only a part of the pulses of a data frame can be subjected to dithering.</li></ol>

5.2 Transceiver with dithering / averaging

0216Dithering is already inherent in practical versions of transceivers. For various reasons, which bring advantages for the implementation, digital modules are interconnected, which are operated at different clock frequencies. Low clock frequencies are useful, for example, where the temporal behavior with these clock frequencies is sufficient, but have the advantage of low power consumption. High clock frequencies are used wherever a fast temporal behavior of the circuit is required. As a rule, the lower clock frequencies are used to carry out the processing of the data of the message frames (coding, decoding). These clock frequencies are only a small multiple of the data rate or the pulse frequency. For the synthesis and the detection of the individual impulses (message symbols) clock frequencies are used which have to be several times the bandwidth of the impulse in the baseband or on an intermediate frequency in order to achieve the desired properties of the circuits. If the clocks are derived from different sources, the different clock frequencies are not synchronized. The frequencies can also be dimensioned so that the smallest common multiple goes towards infinity. At the transition of a signal from one clock domain to the other, this results in a sampling error that has a random distribution. These random deviations produce "jittering" or "dithering" of the transmitted pulses and are generally regarded as an undesirable effect.

0217However, this effect is of particular advantage for the implementation of an exemplary embodiment of a transceiver according to the invention and an arrangement according to the invention for determining the distance, because it implements the dithering of the pulses in the transmitter and also in the receiver of transmitter receivers without further measures.

0218Further circuit measures for implementing dithering are not necessary, but can also be implemented within the scope of this invention.

0219<figref idref="f0006">Fig. 11</figref> shows an example of an implementation of an arrangement of two transceivers with inherent dithering and illustrates the transmission of a message frame in one direction.

0220A transceiver TRX1 acts as a transmitter and the transceiver TRX2 functions as a receiver. A frame is generated, ie encoded, in the transceiver TRX1, and the signal pulses to be transmitted (hereinafter also referred to briefly as pulses) are generated and transmitted at a pulse frequency by a module TXDL. A pulse 72 to be transmitted is sampled by a module TXDH and synthesized as a digital baseband signal

0221A module TX converts the baseband signal into an analog signal, amplifies it and then radiates it via an antenna 74. The pulse frequency is based on a time base that a module GL uses. The module GL passes a resulting clock signal CKL1 to the module TXDL.

0222However, the module TXDH is supplied with a clock signal CKH1, which is generated in a module GH and which is based on an independent time base which is unsynchronized with respect to the module GL.This results in a systematic scanning error which, on a statistical average, corresponds to half the period of CKH1.

0223Reception-related modules of the TRX1 transceiver are shown in dashed lines and are not explained in detail. Their function results from the following description of the reception-related modules of a second TRX2 transceiver.

0224In the second transceiver TRX2, a pulse radiated in via its antenna 76 is amplified in a module RX and digitized into a baseband signal 78. In a module RXDH1, the baseband signal 78 is sampled with a clock CKH2, and a pulse is detected, for example by digital correlation.

0225The digital sampling in the module RXDH1 results in a further systematic sampling error, which on average corresponds to half the period of the clock signal CKH2. Scanning a detected pulse 80 by means of a module RXDL with a clock CKL2 again results in a scanning error which, however, is measured at CKL2 due to a low clock frequency. For this purpose, a pulse 82 sampled by a module RXDH1 connected downstream of module RXDH1 is sampled again by a further module RXDH2 with the clock at CKH2, as a result of which a further temporal sampling error of the received pulse arises. The scanning error of the RXDL module is counted using a CNTH module.

0226The clock frequency of the clock signal CKL2 is based on a time base, which a module GL uses, which supplies the module RXDL with a clock signal. The modules RXDH, RXDH2 and CNTH are supplied with the clock signal CKH2, which is generated in a module GH and which is based on an unsynchronized time base that is independent of the module GL. The modules RXDH and CNTH measure the arrival time of the received pulse with the clock CKH2, so that the measurement accuracy of the arrival time corresponds to the period of this clock. Overall, the individual pulses are systematically shifted on the time axis by superimposing the three sampling errors. The transceivers can be designed and set up so that the ratio of the frequencies CKL1 to CKH1 or CKL2 to CKH2 generates a distribution of the scanning errors that is as even as possible The frequencies CKH1 and CKH2 are designed identically for reasons of design simplification, but are not synchronized in phase and frequency and can therefore be shifted so slightly to one another that the scanning errors are distributed as evenly as possible The clock frequencies of CKL1 and CKL2 are identical, but also unsynchronized and in practice show slight deviations from each other (e.g. quartz tolerances), but can also happen to be synchronous with each other.

0227In addition, all clock frequencies have unsystematic, random phase errors in practice. As already mentioned, noise in the transceivers and on the transmission link can lead to further slight temporal shifts in the pulses.

0228All of these measures and effects lead to a superposition of systematic and random effects and thus to a very randomly distributed time shift of the individual impulses. In addition, the superimposition leads to dithering, which approximates the condition according to Formula 40.

0229<figref idref="f0007">Fig. 12</figref> shows the timing of the transmission of a pulse when using the transceiver arrangement of the <figref idref="f0006">Fig. 11</figref>. The time differences ΔTTX, ΔTRX1 and ΔTRX2 correspond to the systematic scanning errors. The times marked with an asterisk (*) are delays independent of the phase constellation of the various clocks, the values ​​of which are known.

0230A further improvement in the uniform distribution of the dithering can be achieved by restarting the clock generators GH between the transmission of two message frames or by frequency-modulating the clock generators with a pseudo-random sequence during the transmission. The frequency modulation takes place in a very narrow range. In addition, the clock generators GL can be restarted between the distance measurements.

5.3 Accuracy of distance determination when using dithering and averaging

0231Since the resolution of the individual measurements of Δ<i>_TiRXI,</i> see. <figref idref="f0008">Fig. 13</figref>, is limited in practice by the clock frequency available for this purpose, the measurement of the individual pulses is subjected to an error.

0232The limitation results from the necessity to improve the feasibility of a realization (e.g. through maximum possible clock frequencies depending on the manufacturing process of a realization), to reduce the current consumption and to keep the costs of the component (e.g. use of an inexpensive design) low. Because the uncertainty of quantization is statistically ½<i>Tr</i> is the measurement value Δ<i>T_iRXi</i> this amount added.

0233With a finite number of measured values ​​(Δ<i>T_iRXi</i>) the absolute error results from the measurement errors mentioned above <i>E_toA</i> the measured arrival time (see formula 39). <maths id="math0047" num="Formel 39:"><math display="block"><mrow><msub><mi mathvariant="italic">t</mi><mi mathvariant="italic">ToA</mi></msub><mo>+</mo><msub><mi mathvariant="italic">E</mi><mi mathvariant="italic">ToA</mi></msub><mo>=</mo><msub><mi mathvariant="italic">t</mi><mi mathvariant="italic">TOA</mi></msub><mo>⁢</mo><mi>ʹ</mi><mo>-</mo><mi mathvariant="normal">Δ</mi><mo>⁢</mo><msub><mi>T</mi><mi mathvariant="italic">iRXAVG</mi></msub></mrow></math><img file="EP1815267B1_D0047.tif" /></maths>

0234The error is E_ToA assuming ideally evenly distributed deviations of the pulses, as is well known, in the following manner depending on the number of measurements n carried out and the individual measurement resolution T._r(see formula 40). <maths id="math0048" num="Formel 40:"><math display="block"><mrow><msub><mi>E</mi><mi mathvariant="italic">ToA</mi></msub><mo>≤</mo><mo>±</mo><mfrac><mrow><mn>1</mn></mrow><mrow><mi>n</mi></mrow></mfrac><mo>⁢</mo><msub><mi>T</mi><mi>r</mi></msub></mrow></math><img file="EP1815267B1_D0048.tif" /></maths>

0235Since in practice the ideal uniform distribution of the deviations of the detected pulses would be very unlikely or could only be achieved with complex realizations, the error E falls_ToA correspondingly larger than according to formula 40.

0236Further exemplary embodiments are described below, the additional features of which can be applied to the different variants of the method for determining the distance described above, in order to improve its accuracy, security or protocol embedding.

6. Peak detection

0237The accuracy of the determination of a time of reception can be improved by suitable peak detection methods. A digital correlation method is first described below. An analog compression process is then described.

6.1 Peak detection through digital correlation

0238In this method, the pulse from which the arrival time is measured is detected by a digital correlator (so-called sliding correlator). The received signal is digitally quantized and usually stored over the duration of a message symbol. The stored values ​​are then continuously compared with an expected pattern. The result of the comparison is shown as a digital numerical value. To detect a pulse, this numerical value can be compared to a threshold value (fixed threshold), or the largest numerical value reached is selected in a time window. The latter option is used for measuring the time of reception, since it most accurately determines the time with the best signal gain

6.2 Peak detection through analog compression

0239Here, the received signal is summed up (compressed) with an electronic or mechanical circuit (mechanical surface wave filter) in such a way that the received signal is represented as an analog pulse at a certain point in time. The analog compression is designed in such a way that it uses the peak of the analog pulse to determine exactly the point in time (constant delay can be included) with the best signal gain. The analog voltage can be compared with a reference voltage (comparator). By measuring and averaging the times of exceeding and falling below the threshold value of the analog comparator, the peak of the analog pulse can be determined most accurately in terms of time, insofar as the analog pulse has a symmetrical shape.

7. Qualification and identification of signal impulses

0240Measures are described below with which it can be ensured that signal pulses detected on the receiver side are provided for a distance determination. These measures include a gating process, a plausibility check, an integrity check and an identification of received signal pulses.

7.1 Gating

0241The detected pulses of a data frame generate a short-term signal which is repeated for the subsequent pulses with the known pulse period. Since the pulse period is known to the receiver, a grid with the known pulse frequency can be defined for any pulse after synchronization. At the grid points (time of the subsequently expected pulses), short time windows let the detected pulses through to the measuring device for the arrival time, while in the time periods between the windows the detected pulses are blocked or filtered out. Thus, pulses that are detected by interferers, noise and multipath propagation can be masked out, which further increases the reliability and accuracy of the distance measurement. If several pulses fall in the time window, the first pulse is always detected, the subsequent pulses are also hidden. The time window is only a fraction of the pulse period in order to achieve a good filtering effect against the above-mentioned interferers. However, they must have a certain minimum duration because the pulse synchronization is subject to a certain error and the individual pulse intervals are not constant due to the dithering method used.

7.2 Plausibility check

0242Checking the arrival time of the pulses of received data frames for plausibility makes use of known devices and methods of existing message protocols and can therefore advantageously be implemented without great effort. Due to the protocol, the data frames have certain data fields which are used to check the received data frames. The check is carried out for certain codes, which means that the data frames can be classified as permissible and valid, as well as classified. Alternatively or additionally, the validity can be checked at the application level (higher protocol layers or application layer) using signatures in the user data areas (payload) of data frames. If the plausibility check of data frames is successful, the arrival times of the individual impulses, which are used as message symbols, can also be regarded as plausible.

7.3 Integrity check

0243The integrity of the data frames can be checked to determine whether the detected pulses were actually sent out by the transmitter. In this case, checksums are generated in existing message protocols over certain fields of the data frame and attached to the data frame (CRC). In the frame decoder of the receiver, for example, the checksum for the fields actually received is then recalculated and compared with the checksum received. If the test is successful, then a very high statistical certainty (better than 10¹⁰ ) determine whether the impulses were received in an unadulterated manner. By using this well-known set-up of existing message protocols, the reliability and accuracy of the distance measurement can be efficiently improved, since only the actually transmitted pulses of the data frames are used to determine the arrival time.

7.4 Identification of the signal pulses

0244The affiliation of pulses to a transceiver and thus to a specific position can be done via the unique identification of the data frames. The address fields (e.g. IEEE station addresses) of existing message protocols are also used, which ensure a clear assignment (origin) of a message to a sender-recipient. The arrival times of the pulses can thus be unambiguously assigned to a particular transceiver and the reliability of the distance measurement is thus improved without additional effort

8th. Exchange of measurement data for distance determination

0245To calculate the pulse duration and the distance from it, certain measured values ​​must be exchanged between the cooperating transceivers.

0246One possibility is the exchange of the send and receive times of the message frames, from which the round trip and response times and, in turn, the pulse transit times and the distances can be calculated. Alternatively, it is also possible to exchange the runout and response time intervals already determined in the transmitter receivers.

0247The time measurement values ​​can be exchanged symmetrically, which means that the distance can be calculated in both cooperating transceivers or only one-sided transmission is carried out if the calculation of the distance in one of the transceivers is sufficient. The time measurement values ​​can be transmitted either publicly (within reach of any transceiver) or secretly (only understandable to the two cooperating transceivers).

8.1 Exchange of transmission and reception times (ToA)

0248In order to calculate the round trip and response times, from which the pulse transit time or distance is then calculated, the measured reception and transmission times of the message frames can be transmitted. The time values ​​are transmitted in a predefined or later negotiated format. The advantage of the transmission is that not every transceiver has to be equipped to calculate the round trip or response times. If the knowledge of the distance is not only useful and desirable between the cooperating transceivers, the transmission of the measured times of reception and transmission can be carried out efficiently, for example as a broadcast (saving of bandwidth of the message channel, saving of electrical energy). The measured times can be corrected before transmission due to falsification by external influences (e.g. temperature). Alternatively, the correction can also be carried out in the transceiver that calculates the round trip and response times. To do this, the correction values ​​must either be transferred additionally or must already be known. The optional use of an "eternal" time scale also has the advantage that the measured values ​​can easily be uniquely assigned to the respective message frame.

8.2 Transmission of the round trip and response time intervals

0249Alternatively, the runout and response time intervals can be transmitted to calculate the pulse duration and the distance from it. The time values ​​are transmitted in a previously defined or later negotiated format.

0250If the knowledge of the distance is not only sensible and desirable between the cooperating transceivers, the transmission of the round trip and response times can also take place as a broadcast, for example. The calculation of the round trip and response times from the measured reception and transmission times of the message frames need only be carried out once in this variant. The determined times can also be corrected due to falsification by external influences before the transmission. Alternatively, the correction can also be carried out in the transceiver that calculates the distance. To do this, either the correction values ​​must also be transferred or they are already known. With the transmitted times, however, the assignment to certain message frames is necessary, which must be transmitted in addition to the time values ​​(e.g. by numbering the message frames).

8.3 Transmission of the pulse duration or the distance

0251If the calculation of the pulse transit time or the distance is carried out only in one of two cooperating transceivers, it is possible to transmit these calculated results. This has the advantage that the computational effort, although it is relatively small, only has to be carried out once. In addition, only certain transceivers need to be equipped accordingly. If the knowledge of the distance is not only sensible and desirable between the cooperating transceivers, the transmission of the distance can also take place as a broadcast, for example (see 5.3.1). In addition, the distance calculation only has to be carried out once.

9. Measures to protect and increase the security of the process

9.1 Authorization of distance measurement

0252The measurement of distances requires cooperating transceivers for the exchange of messages. The distance measurement can, however, be permitted or blocked depending on a specific situation. Blocking is necessary, for example, to guarantee the "privacy" of a certain user group or to control the traffic density of the transmission channel. The test procedure in a transceiver, which grants permission to measure the distance and thus agrees to cooperate with another transceiver, can be negotiated beforehand or set in advance. Well-known authentication methods are used in the test procedure. Authentication can take place, for example, via station addresses, signatures, encrypted signatures or encrypted messages. One-time signatures and / or one-time keys can be used to increase the security of the method. After successful one-sided or mutual authentication, the transceivers then cooperate in the individual steps, such as exchanging messages and exchanging the measurement data of the distance measurement (e.g. round trip and response times). A simple way of integrating the test method into the distance measurement message exchange is to use encrypted messages that use a secret key that is known on both sides. Only if the decryption of a first data frame at a transceiver was successful does the transceiver send the second (encrypted) data frame, etc. until a message exchange takes place, for example, according to one of the multi-way processes used

9.2 Encrypted transmission as part of the distance determination

0253The use of an appropriate encryption method with high security also serves to protect privacy and protect against eavesdropping data. For example, well-known substitution and transposition methods and methods combined therefrom can be used. Long key lengths (at least 128 bits) and the use of one-time keys guarantee the corresponding protection of the process. The existing encryption method of a message protocol used for the distance measurement can be used for this. The following data can be exchanged for the distance measurement: transmission and reception times, response and round trip intervals, calculated pulse delay times or distances calculated from them. The data can be secretly exchanged between the cooperating transceivers, or can also be transmitted publicly in certain applications, for example to give any transceiver the opportunity to gain knowledge of the distances between various other transceivers. This is useful, for example, where the distance information between the transceivers of a network should be spread as quickly and efficiently as possible. By using a secret but shared key, for example, all "initiated" transceivers can listen to this information. If no protection of this information is necessary, it can optionally be transmitted unencrypted.

9.3 Secret response time intervals

0254As illustrated in the methods of this invention, the response times T_reply be known to calculate the distance. For this purpose, the determined, exact response times or only the deviation from a specified response time are transmitted to the cooperating transceiver for the calculation of the distance. The deviations from the specified response time cannot be avoided in practical implementations and are therefore permitted within certain tolerance limits. The definition of the tolerance of the response time depends on the desired accuracy of the distance measurement and this in turn on the difference between the response time intervals or their mean values. The response time or its deviation can be transmitted in encrypted form and thus made inaccessible to a third transceiver, which offers a certain protection of the distance determination. However, since the response time could be known within certain tolerance limits, for example by a known, generally applicable definition in a realization, by measuring realizations with a previously unknown but firmly implemented response times (e.g. the same type of integrated circuit) or by listening to messages from transceivers with a known distance and then correlating or calculating the response time, the distance could be successfully determined with some accuracy (e.g. ± 100 ns tolerance of the response time corresponds to a distance to be covered a pulse of ± 30 m). If the deviations are evenly distributed, listening to the message exchange over a longer period of time and then averaging the time measurements could determine the distance again with high accuracy (if the realization or listening to the message exchange over a known distance is known, the average would also be the Response time known). Therefore, with this method, the response time is changed by the user in steps larger than those already caused by the tolerances in such a way that the variation of the response time deviations occurs unevenly (asymmetrically to the mean). A secret response time can be set or negotiated in a closed user group and changed at any time. Optionally, it is possible to change the response times according to a previously agreed scheme. In addition, the response times can also be changed according to a random or pseudo-random pattern and these can then be made known to the cooperating station by encrypted transmission. It should only be noted that the response time differences during a distance measurement are within the tolerance limits.

10th Measures to improve the compensation of temperature and supply voltage variations

10.1 Complementary signal pulses

0255Deviations of the carrier frequency in the transmitter from the selection frequency in the receiver can cause deviations in the arrival time of the detected symbols in certain modulation methods. Since the transceivers are not synchronized in phase and frequency and do not have to be synchronized or mutually calibrated to one another for the method of this invention, deviations in the frequencies of the transceivers (frequency offset effect) cannot be ruled out. In practice, the mixing frequencies derived from the carrier and selection frequencies can be derived and calibrated with good precision from a local reference frequency (quartz oscillator), but the reference frequencies are also subject to deviations (e.g. quartz tolerances). An advantage of this invention is the low impact of the quartz tolerances so that industrially available types of quartz can be used. This advantage must not be offset by the effect described here. Furthermore, for example, temperature changes in a circuit implementation (e.g. by changing the ambient temperature or by self-heating) cause a slight change in the derived or calibrated mixing frequencies, which can lead to the significant change in the arrival time of the detected symbols. So-called complementary pulses are therefore used to compensate for this effect. The complementary pulses have the property of causing temporal deviations of the detected pulses with the same amount, but with opposite signs. Ats complementary pulses can be used, for example, monotonically rising and falling chirp pulses that have an identical center frequency and the same duration. If the number of complementary pulses detected is equal, the sum of the time deviations is always zero. Since the various complementary pulses are generally used as different information symbols and data are represented with the information symbols, the distribution and the quantitative ratio of the complementary pulses to one another depend on the data information which is to be transmitted. An arbitrary data frame therefore consists of an undetermined quantity ratio of the complementary pulses with an unknown distribution. In averaging methods of this invention, the arrival times of a certain number of detected pulses are averaged. When using the complementary impulses, it must also be ensured that the complementary impulses are averaged equally. This is achieved in this invention in that the various pulses are identified and the arrival times are assigned to the corresponding pulses. By adding the same number of the respective arrival times and parts by the total number of the measured arrival times, the required averaging takes place and thus the compensation of the frequency offset effect. Since, as already explained, the distribution and the quantity ratio of the complementary impulses depend on the information itself, this can turn out to be unfavorable for the averaging. However, this can optionally be improved within the scope of this invention in that the data are substituted in accordance with a pseudo-random pattern before sending and this substitution is undone again after receiving (so-called scrambling). Experience has shown that this results in a better uniform distribution of information symbols and thus different impulses. Scrambling is usually already present in existing message protocols, so that it can be used for this purpose. In addition, the number of reception times to be measured equally can also be adjusted during the operation of a transceiver in order to achieve a high success rate for the equal averaging. Once the required number of frames has been reached, the user can be notified that the required number has been reached, so that a new required number can be set for receiving the next frame of data.

10.2 Characterization tables and functions

0256As is well known, implementations of electronic circuits have the property of influencing the temporal behavior of electrical signals depending on external conditions. Both influences that influence the properties of the circuit realization during the production of a circuit realization (eg integrated circuit) and changing influences during the operation of the circuit realization come into consideration. The influences during production are known as tolerance-related sample variations, while the external influences during operation have an effect on the temperature and supply voltage. As a result, constant but different time delays can occur in the individual device copies at a specific temperature and supply voltage, which lead to significant deviations in the measurement of the reception times of the pulses and thus adversely affect the accuracy of the distance measurement.

0257This detail of the invention uses so-called characterization tables and / or functions which measure or otherwise determine the influences of the temperature and supply voltage of a specimen on the temporal behavior. The characterization tables and / or functions are permanently assigned to a copy and can be stored, for example, in the implementation (e.g. in the PROM / flash memory of the integrated circuit or in the control software of the respective device). In addition, the temperature and the supply voltage can be measured in the implementation and, from the stored characterization information, precise circuit-related delay times can be taken into account when calculating the pulse delay time and thus the distance. The characterization information can be obtained once during production or in operation by means of a calibration process (e.g. can be obtained and stored by known removal of two transceivers) of the circuit implementations or devices.

10.3 Use of pairs of transceivers

0258The detail of this invention is to compensate for the influences of temperature and supply voltage by determining these influences over a known distance. Two transceivers, each with a separate antenna, are installed in a device for distance measurement. The distance between the antennas is known and the size of the circuit-related delay times can be determined from the calculated pulse transit time between the two transceivers and the actual distance. Both transceivers are structurally arranged in the device and the device is installed spatially so that they are exposed to the same ambient temperature. In addition, both transceivers are from the same supply voltage source (e.g. Battery powered. By averaging the circuit-related delay times caused in the transmitter and in the receiver of the transmission path between the pair of transceivers and taking these delay times into account when determining an unknown distance to a pair of transceivers or individual transceivers, the temperature and supply voltage can be reduced voltage dependent delay compensated and thus the precision of the distance measurement be further improved. This method is also suitable for compensating for the effects of the multipath propagation on the assumption that the influences of the multipath propagation on the distance measurement between the transmitter receptions of the pair with a known distance are identical to transceivers with a different, unknown distance. This possibility of compensating for multipath propagation can primarily be used where the propagation properties of the medium between any positions of the transceivers are almost identical (e.g. in homogeneous closed rooms such as tubes, tunnels, halls, hangars, etc.).

11. Multiple measurements

0259All of the methods shown can also be used for multiple measurements of the concentricity intervals with subsequent averaging. The determined pulse transit times or distances are collected and then averaged arithmetically.<maths id="math0049" num="Formel 41:"><math display="block"><mrow><msub><mrow><mi>T</mi></mrow><mrow><mrow><mi mathvariant="italic">prop</mi></mrow></mrow></msub><mo>=</mo><mfrac><mrow><msub><mrow><mi>T</mi></mrow><mrow><mrow><mi mathvariant="italic">prop</mi></mrow><mn>1</mn></mrow></msub><mo>+</mo><msub><mrow><mi>T</mi></mrow><mrow><mrow><mi mathvariant="italic">prop</mi></mrow><mn>2</mn></mrow></msub><mo>+</mo><mn>..</mn><mo>+</mo><msub><mrow><mi>T</mi></mrow><mrow><mrow><mi mathvariant="italic">prop</mi></mrow><mi>n</mi></mrow></msub></mrow><mrow><mi>n</mi></mrow></mfrac></mrow></math><img file="EP1815267B1_D0049.tif" /></maths><maths id="math0050" num="Formel 42:"><math display="block"><mrow><mi>d</mi><mo>=</mo><mfrac><mrow><msub><mrow><mi>d</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>+</mo><msub><mrow><mi>d</mi></mrow><mrow><mn>2</mn><mo>+</mo><mn>..</mn><msub><mi>d</mi><mi>n</mi></msub></mrow></msub></mrow><mrow><mi>n</mi></mrow></mfrac></mrow></math><img file="EP1815267B1_D0050.tif" /></maths>

0260Alternatively, the round trip and response times can be accumulated and then divided by the number of measurements. Formula 43 shows the calculation of the accumulated round trip and response times for an arithmetically averaged pulse running time using the 3-way method.<maths id="math0051" num="Formel 43:"><math display="block"><mrow><msub><mrow><mi>T</mi></mrow><mrow><mrow><mi mathvariant="italic">prop</mi></mrow></mrow></msub><mo>=</mo><mfrac><mrow><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">roundA</mi><mo>⁢</mo><mn>1</mn></mrow></msub><mo>+</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">roundB</mi><mo>⁢</mo><mn>1</mn></mrow></msub><mo>+</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">roundA</mi><mo>⁢</mo><mn>2</mn></mrow></msub><mo>+</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">roundB</mi><mo>⁢</mo><mn>2</mn></mrow></msub><mo>+</mo><mn>..</mn><mo>+</mo><msub><mi>T</mi><mi mathvariant="italic">roundAn</mi></msub><mo>+</mo><msub><mi>T</mi><mi mathvariant="italic">roundBn</mi></msub></mrow><mrow><mn>4</mn><mo>⁢</mo><mi>n</mi></mrow></mfrac><mo>-</mo><mfrac><mrow><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyA</mi><mo>⁢</mo><mn>1</mn></mrow></msub><mo>+</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyB</mi><mo>⁢</mo><mn>1</mn></mrow></msub><mo>+</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyA</mi><mo>⁢</mo><mn>2</mn></mrow></msub><mo>+</mo><msub><mrow><mi>T</mi></mrow><mrow><mi mathvariant="italic">replyB</mi><mo>⁢</mo><mn>2</mn></mrow></msub><mo>+</mo><mn>..</mn><mo>+</mo><msub><mi>T</mi><mi mathvariant="italic">replyAn</mi></msub><mo>+</mo><msub><mi>T</mi><mi mathvariant="italic">replyBn</mi></msub></mrow><mrow><mn>4</mn><mo>⁢</mo><mi>n</mi></mrow></mfrac></mrow></math><img file="EP1815267B1_D0051.tif" /></maths>

12th Use for distance determination over long distances

0261The method according to the invention aims at a distance determination in the range up to 10 km. However, it can also be used as part of a method for determining distances over larger distances.

0262The range of a message transmission or maximum distance between two transceivers is limited for various reasons, which means that only distances up to a certain limit can be determined directly. The limitation of the range mostly results from legal regulations (e.g. maximum output power of the transmitter) and from technical as well as economic reasons (inexpensive transceivers).

0263An increase in the range of the distance measurement can be achieved by measuring shorter intermediate distances in a network of transceivers, the intermediate distances are transmitted to the transceiver of an end point of a longer distance measurement, where direct message transmission between the end points would not be possible, and the intermediate results there a function to calculate the total distance.

0264Various approaches can be used to implement this function. A first simple possibility is the formation of the sum of the intermediate results for the total distance on the assumption that all transceivers are on a straight line.

0265An extension of this possibility is the determination of several sums that can arise from different distances between the end points. The smallest distance can then be selected as the most accurate estimate by comparing the sums. This method is more suitable in practice since the transceivers are very unlikely to be all on a straight line.

0266The most precise way to determine the distance across several transceivers is to use the lateration and angulation known per se for calculation. The distances between the transceivers are determined, which allow a clear geometric representation of the spatial arrangement of the end points and the required intermediate points. Then the direct distance between the endpoints can be calculated using lateration and angulation. The method can be used both for arrangements of transceivers on a surface (two-dimensional) or in space (three-dimensional).

13. Utilization of standardized message protocols

0267Existing message protocols can be used within the scope of this invention to improve the accuracy, reliability and security of the distance measurement.

0268The method according to the invention enables the transmission of any application data and the simultaneous distance measurement between two transmitter receptions. On the other hand, the methods and mechanisms for data transmission specified in the message protocols also serve to improve the accuracy, reliability and security of the distance measurement.

0269The message protocols that can be used for the process are defined, for example, in public standards of international organizations (e.g. IE-EE), commercial interest groups (e.g. Bluetooth) or as private industry standards (e.g. nanoNET) . The general knowledge, the dissemination and the presence of proven and powerful methods and mechanisms in existing message protocols increase the acceptance of an integrated method of distance measurement and significantly simplify the dissemination of the methods and their implementation in practical implementations (transceivers). Organizational efforts sometimes dictate certain message protocol standards for certain applications. The invention makes it easier to integrate distance measurement in these applications.

0270The ISO / OSI-1 layer (physical layer, PHY) agreed in the standards can, if appropriate, continue to be used. The layer ISO / OSI-2 (data link layer, MAC / Data Link Layer) is very useful for the process and there are enough suitable message protocols that still allow the integrated distance measurement. All higher layers according to the ISO / OSI model can be used with the method, in particular the layer ISO / OSI-6 (presentation layer) is useful for the method.

0271This enables an efficient and integrated method which does not require any additional bandwidth of the transmission channel for the distance measurement. In addition, the circuit parts of a realization that are necessary for data transmission are also used for the distance measurement, which enables inexpensive and energy-saving transceivers.

0272Existing standards can also be easily expanded due to the reusability of the layers ISO / OSI-2 and upwards. This enables an efficient standardization process, since under certain circumstances only the physical layer has to be redefined. In addition, existing knowledge and existing designs allow the cost-effective and time-saving expansion of realizations using this process (design re-use). To optimize the process, certain layers of existing message protocols can be expanded in such a way that the extension does not conflict with the previous standard (e.g. extension of the command set of the Link Protocol Manager of layer ISO / OSI-2). Backward compatibility with the existing message protocols is maintained.

0273In the event that a standard including the physical layer (eg the private industry standard nanoNET) can be used without restriction, only an extension of the implementations (eg integrated circuits) is required. The existing implementations can still be used for exclusive data transmission.

13.1 Utilization of Layer 2 protocols

0274The message exchange according to the three-way and n-way method can be carried out with a time slot method (Time Division Multiple Access, TDMA) of the data link layer, ie layer 2 in the ISO / OSI reference model. Message frames are exchanged between two cooperating transmitter receivers at equidistant time intervals, and the respective transmission and reception times are measured, and the round trip and response time intervals are determined therefrom. The equidistant time intervals can be used to meet the symmetry requirement of the method according to the invention with regard to the response time intervals.

0275Additional message traffic can be permitted between the message frames, for example the transmission of confirmation packets to the message frames used for the method as data packets.

0276The exchange of messages according to the double-sided and multi-double-sided two-way method can be realized with the widely used error correction protocol. In this case, confirmation packets are sent back as confirmation for correctly received data packets, which generally have a predetermined distance from the data packets. Both packets act as a message frame pair according to these procedures. If the packet distances are constant during a measurement, the symmetry requirement of this method is also met.

13.2 Use of message protocols to exchange the measured values

0277To calculate the distance, an exchange of the time measurement values ​​of the physical layer (e.g. determined round-trip and delay times) with the cooperating transceiver is necessary. In addition, the calculated distances can be exchanged with other transceivers.

0278The data can be exchanged between the data link layers of the transceivers or the time values ​​are transmitted as data from the application layer.

0279The first variant requires the expansion or introduction of a link protocol manager in the data link layer. The link protocol manager enables, for example, the control of the data flow of the application data at the level of the data link layer or the negotiation of the key used for the encrypted data transmission. By defining new commands, the transmission of the time measurement values ​​can be negotiated, as can the transmission of the time measurement values ​​themselves.

0280Under certain circumstances, the Link Protocol Manager can be expanded in its command set so that it remains downward compatible with the existing command set. As a result, the use of transmitter receivers that do not have the extended link protocol manager for pure data transmission without distance measurement is still possible.

0281In the variant of the transmission of the time values ​​as data of the application layer, the data link layer can be used unchanged, however an assignment of the message frames of the data link layer to the time measurement values ​​of the physical layer up to the application layer must be maintained. Since according to the ISO / OSI model there are additional layers between the application layer and the data link layer and buffering and fragmentation of message frames can be carried out in these layers, the assignment of time measurement values ​​to the message frames of the application layer is not always unambiguous. This problem can be avoided if the application layer is located directly on the data link layer and thus an unambiguous assignment is retained.This option is reserved for all very simple systems that, for example, do not have any network (ISO / OSI-3, network layer) and do not use a transport layer (ISO / OSI-4, Transport Layer) or where certain properties of these layers are integrated in a non-ISO / OSI-compliant data link.

0282Alternatively, the assignment can also be made via so-called service interfaces, which enable a direct and time-unique link between the application layer and the data link layer.

13.3 Use of message protocols to protect and secure the distance measurement

0283For the protection and security of the process, the encryption and its supporting mechanisms (e.g. key negotiation) of existing message protocols can be used. This includes protection against eavesdropping by encrypting the data that is exchanged with transceivers for distance measurement and protection against unauthorized use of the distance measurement. The use of the distance measurement can be authorized with the authorization and authentication mechanisms of the message protocols used.

0284The encryption can be carried out in the different layers according to the ISO / OSI model. In practice, encryption usually takes place in the data link layer, in the presentation layer or in both layers simultaneously. In most existing message protocols, encryption is provided in the data link layer (e.g. IEEE 802.11, WEP). As a rule, very powerful encryption methods are provided in the existing standards.

0285The authorization and authentication mechanisms are mostly present in the presentation layer or data link layer. Additionally or alternatively, they can be present in every other layer of the message protocol used, as well as in the application layer.

0286The use of encryption and the authorization mechanisms for distance measurement generally do not require any additional bandwidth for the transmission channel. The devices do not have to be installed in practical implementations, since they are already available for the transmission of the application data.

14. Embodiments of transmitter receivers

0287Various exemplary embodiments for transceivers according to the invention and their components are described on the basis of the figures described below.

14.1 Block with external distance calculation and application module

0288In one in <figref idref="f0008">Fig. 14</figref> The first embodiment variant of a transceiver according to the invention shown is combined in an integrated circuit module 100 (Integrated Circuit Device), also referred to briefly as a module, for several modules and implemented as an integrated circuit. An external CALC / APP module 102 is with the integrated module 100 via logical connections<i>T_{reply '}, T_round'</i> and CTRL / DATA 104, 106 and 108 connected. The logical connections can be combined in a common serial or parallel user interface.

0289An analog transmitter 110 (TX) modulates the signal pulses to be transmitted onto a carrier frequency and transmits them to an external antenna 112. An analog receiver 114 amplifies, demodulates and detects radio pulses radiated onto the antenna 112.

0290A baseband / MAC module 116 (MAC = Medium Access Controller) performs coding of data frames to be transmitted and decoding of received data frames, which consist of a sequence of radio signal pulses.

0291The baseband / MAC module 116 also checks received data frames. By checking the data frames in the baseband / MAC module 116, the physical assignment of the received pulses to specific transmitter receptions is secured and a reference point for measuring the round trip intervals and generating the response time is established, for example a pulse at the end of the frame. Furthermore, the check is carried out on the basis of the data represented by the impulses, from which in turn the plausibility is checked by means of signatures, the integrity of the data is secured by means of checksums and the identification is ensured by means of unique sender-receiver addresses.

0292Optionally, the data in the baseband / MAC module 116 are encrypted or decrypted for the secure transmission of the protocol and user data, including the distance measurement information to be exchanged between transmitter receptions. The baseband / MAC module 116 additionally controls access to the message channel used in accordance with an agreed scheme. Existing message protocols can be used, such as public or private standards.

0293In the baseband / MAC module 116, after successfully checking a received first data frame, a second data frame to be sent is also generated, which is also referred to as a subsequent data frame. The following data frame is sent after a precisely defined time delay, the response time interval, relative to the time of reception of the first data frame. The response time interval is over one at the connection<i>T_{reply '}</i> 104 available value adjustable and changeable.

0294Furthermore, the round trip interval between the transmission time of a first data frame and the reception time of the subsequent data frame is measured and a value for this time via the connection T_{round '} 106 issued.

0295The external CALC / APP module 102 exchanges control information with the baseband / MAC controller 116 via the CTRUDATA 108 connection, transmits the protocol and user data to be sent and received via this connection and calculates from the values ​​for the round trip intervals (<i>T_round'</i>) and the response times (<i>T_reply</i>) the impulse transit times, from which in turn the distances between two communicating transmitter receptions can be calculated. Applications of wireless data transmission and distance measurement can also be integrated in this module 102.

14.2 Integrated distance calculation module

0296<figref idref="f0009">Fig. 15</figref> shows a further embodiment of a transceiver, which is characterized by an integrated distance calculation module. The following illustration focuses on the differences between the transceiver and the<figref idref="f0009">Fig. 15</figref> compared to that of <figref idref="f0008">Fig. 14</figref>. Here are compared to the embodiment of<figref idref="f0008">Fig. 14</figref> functionally equivalent modules used the same reference numerals.

0297In the in <figref idref="f0009">Fig. 15</figref> The embodiment variant shown is provided in a module 120 as an integrated circuit in addition to the baseband / MAC module 116, the analog transmitter 110 and the analog receiver 114, a CALC module 122 for calculating the distance. In contrast to the first variant, the distance calculation in the present variant is therefore integrated in module 120.

0298The function of the analog transmitter and receiver modules and the baseband / MAC module is identical to the first embodiment. The differences from the first variant are explained in more detail below.

0299Values ​​for the distance calculated in the CALC module 122 are transmitted to an external application (APP) module 126 via a connection d '124. The APP module 126 exchanges control information as well as protocol and user data with the baseband / MAC module 116 via the connection CTRL / DATA 108. In addition, the APP module 126 can initiate the distance calculation in the CALC module 122 via the connection CTRUDATA 108, or the distance calculation can be synchronized with the internal baseband / MAC module 116 via an internal bus CTRL / DATA 128.

0300Applications of wireless data transmission and distance measurement can in turn be integrated in the APP module 126. In the present second embodiment variant too, the logical connections d '124 and CTRL / DATA 108 can be combined in a common serial or parallel user interface.

14.3 Integrated distance calculation and application module

0301<figref idref="f0009">Fig. 16</figref> shows a further embodiment of a transceiver, which is characterized by an integrated distance calculation and application module. The following illustration focuses on the differences between the transceiver and the<figref idref="f0009">Fig. 16</figref> compared to that of <figref idref="f0008">Fig. 14</figref> and <figref idref="f0009">15</figref>. Here are compared to the embodiments of the<figref idref="f0008">Fig. 14</figref> and <figref idref="f0009">15</figref> functionally equivalent modules used the same reference numerals.

0302In the variant of the <figref idref="f0009">Fig. 16</figref> is the CALC / APP module 102 (<figref idref="f0008">Fig. 14</figref>) in addition to the baseband / MAC module 120, the analog transmitter 110 and the analog receiver 114 in one module as an integrated circuit 130.

0303An external connection 132 is optionally available for the application control and the application data (e.g. human-machine user interface, connection for sensors and actuators). The function of the analog transmitter and receiver modules 110 and 114 and of the baseband / MAC module 116 is also identical to the first embodiment variant in this variant. The function of the integrated CALC / APP module 102 is also identical to the first embodiment variant.

15. Implementation of the measurement of the round trip interval and the response interval

0304In one in <figref idref="f0010">Fig. 17</figref> The general embodiment variant of a transceiver shown is initiated via a control input Command 140 to generate a message packet by coding protocol and user data in the baseband / MAC module 142 to form a sequence of digital pulses 144. In the transmitter module 146, the pulses are modulated, amplified and emitted via the antenna 148

0305Received pulses are also forwarded via the antenna 148 to the receiver module 150, amplified there, demodulated and detected at the time of the strongest signal of the pulses.

0306A sequence of digital pulses 144 is detected in the baseband / MAC module 142 as a data frame by decoding the protocol and user data. The round-trip time intervals from a respective first data frame sent to a respective subsequent data frame received are measured in the baseband / MAC module 142 and via a connection T._{round '} 152 values ​​output for this time.

0307A status control output 154 shows the validity of the values ​​for the T_round-Connection 152.

0308The response time interval from the time of reception of a first data frame to the time of transmission of a subsequent data frame is via a T_reply- Port 156 set as a value.

0309In a special embodiment variant, a time difference between an actual response time interval and a set response time interval is additionally determined by the time at the T_reply-Connection 154 measured value measured. In the special embodiment, this time difference is caused by the sampling error of the detected pulses between receiver module 150 and baseband / MAC module 142. Values ​​for the time differences are provided on a Δ additionally provided in this special embodiment<i>T_reply'</i>Port 158 ​​is output and the validity is displayed via the status control output 154.

16. Implementation of a control of the concentricity measurement

0310<figref idref="f0011">Fig. 18</figref> shows in a simplified block diagram a transceiver that implements a measurement of the round trip interval. The transmitter branch of the transceiver<figref idref="f0011">Fig. 18</figref> comprises a transmitter module (TX) 172, which is connected on the input side to a module FRAME-CODEC 162 and on the output side to an antenna 173. The module FRAME-CODEC 162 is part of the baseband / MAC module 116 described above. The receiver branch of the transceiver<figref idref="f0011">Fig. 18</figref> comprises an analog receiving module (RX) 170 connected on the input side to the antenna 173, which is followed by digital modules RXDH 174 and RXD 176 in the signal flow. The RXD 176 module is connected on the output side to an input of the FRAME-CODEC 162 module.

0311The mode of operation of the transceiver is described below <figref idref="f0011">Fig. 18</figref> described in the control of a concentricity measurement. Here, the concentricity interval is measured with a counter module 160, which is also referred to as CNT module 160. The CNT module 160 is also part of the baseband / MAC module 116 described above.

0312The counter module 160 is reset and started by the FRAME-CODEC module 162 when a first message frame is sent out at the beginning of a signal round trip. The FRAME-CODEC module 162 also encodes the data frames into a sequence of digital pulses.

0313After sending out the data frame, the FRAME-CODEC module 162 expects a second data frame in the form of a sequence of digital pulses on the receiver side, which is also referred to as a subsequent data frame. The counter module 160 is stopped after the detection of a subsequent data frame and the count value reached when the stop is then applied to a CNTround connection 164 of the counter module 160 unchanged.

0314During or after receipt of the subsequent data frame, the decoding and checking of the subsequent data frame is carried out by the FRAME-CODEC module 162.

0315The module FRAME-CODEC 162 detects a reference time based on a predetermined reference point in the data frame both for resetting and starting as well as stopping the counter module 160. The point in time at which the round-trip time measurement is derived from a reference point in the form of a specific pulse or a specific position in the message frame. This can be any position that is uniform in all message frames. It makes sense to use the detection time of the frame synchronization, which is generated by the FRAME-CODEC module 162. This reference point is available in all message frames and is unique, both when sending and when receiving. Therefore, this reference point is also used to end the concentricity measurement.

0316The synchronization with the distance calculation unit takes place via the control connections Command 166 and Status 168. A new round trip measurement is activated via the Command control connection 166, and the status control connection 168 signals the presence and the validity of the subsequent data frame and a new measured value for one Concentricity interval CNTround.

0317In the present implementation, the modules FRAME-CODEC 162 and CNT 160 are supplied with a common clock CK and thus work synchronously.

0318The following explains in more detail how the circuit described improves the resolution of the measurement of the concentricity interval by measuring and taking a scanning error into account. A pulse (a) detected by the analog receiving module (RX) 170 is sampled in the RXDH module 174 with a clock CKH. The sampling error corresponds on average to half the period of the clock applied to the CKH. Scanning the detected and sampled pulse (b) in the RXD module 176 results in a further, but substantially larger, temporal error, since the clock CK has a significantly longer period than the clock CKH. By measuring and taking this time into account, a better resolution of the concentricity interval is achieved. In practice, clock frequencies of approx. 100 -200 MHz with an accuracy of ± 200 ppm is sufficient, since this precision is sufficient due to the special multipath method of the present invention. The resolution can be further increased by the dithering and averaging methods described above.

0319There are two design variants for realizing the measurement of the scanning error. In a first embodiment variant, a second counter module (CNTH) 178 is started by a pulse (b) sampled with the clock CKH via a connection 180. The received pulse (c) sampled and delayed by the clock CK causes the second counter module (CNTH) 178 to be stopped via a connection 182, the count value of which remains unchanged on one after the stop<i>CNTH_Δround</i> - Connection 184 is present.

0320In a second alternative embodiment, the second counter module (CNTH) 178 is started by the sampled and delayed receive pulse (c) via a connection 182. A subsequent detected pulse (b), sampled with the clock CKH, causes the second counter module (CNTH) 178 to be stopped via a connection 180, the count value of which, after the stop, is also unchanged on one<i>CNTH</i>_{Δ<i>round</i>}- Connection 186 is present.

0321The FRAME-CODEC 162 module can activate the measurement of the scanning error for a specific pulse or multiple pulses of a data frame or a specific position or in a specific time range of the data frame via a control connection 184. The control connection 184 additionally allows the second counter module 178 to be reset.

0322The synchronization with the distance calculation unit takes place with the control connections Command 166 and Status 168. In addition, the status connection 168 signals the presence and the validity of a new measured value for the scanning error <i>CNTH_Δround</i> the round trip time <i>T_round</i>. The calculation of the round trip time<i>T_round</i> takes place from the output values, <i>CNTH_Δround</i> and <i>CNT_round</i>, the counter modules and the periods of the clock frequencies at CK and CKH, whereby additional circuit-related delays must be taken into account.

17th Implementation of a control to generate the response time interval

0323<figref idref="f0012">Fig. 19</figref> shows a transceiver that implements a controller for generating the response time interval. The structure of the transceiver is similar to that<figref idref="f0012">Fig. 19</figref> in many elements that of <figref idref="f0011">Figure 18</figref>. Therefore, be opposite here<figref idref="f0011">Fig. 18</figref> same modules used the same reference numerals.

0324<figref idref="f0012">Fig. 19</figref> shows, however, as will be explained in more detail below, some inputs and outputs of the modules of the transceiver which are relevant for controlling the generation of the response time interval <figref idref="f0011">Fig. 18</figref> are not shown. Conversely shows<figref idref="f0011">Fig. 18</figref> some inputs and outputs of the modules of the transceiver relevant for the control of the concentricity measurement, which are described in the present <figref idref="f0012">Fig. 19</figref> are not shown. Functions implemented in the respective modules are linked to the respective inputs and outputs, which are described in the above description of<figref idref="f0011">Fig. 18</figref> and in the following description of the <figref idref="f0012">Fig. 19</figref> are explained.

0325Since the round-trip time measurement and response time generation do not overlap in time, the implementations of the <figref idref="f0011">Fig. 18</figref> and <figref idref="f0012">19</figref> can be combined into a common circuit. A preferred exemplary embodiment of a transceiver therefore implements a combination of the two exemplary embodiments of the<figref idref="f0011">Fig. 18</figref> and <figref idref="f0012">19</figref> together.

0326At the transceiver <figref idref="f0012">Fig. 19</figref> the response time is generated with the CNT or counter module 160. The modules CNT 160 and FRAME-CODEC 162 are also part of the baseband / MAC module 116 already explained above.

0327The counter module 160 is reset and started by the FRAME-CODEC module 162 upon receipt of a request data frame at the beginning of a signal round trip. The FRAME-CODEC module 162 takes over the decoding and checking of the data frame consisting of a sequence of digital pulses during or after the reception.

0328The counter module 160 is activated after reaching or via a connection <i>CNT_reply</i> 190 applied value for the response time interval is stopped, and a response data frame is sent out, the FRAME-CODEC module 162 taking over the coding of the data frame into a sequence of digital pulses.

0329The module FRAME-CODEC 162 detects a predetermined reference point in the respective data frame for resetting and starting the counter module 160 after receiving a request data frame as part of a signal round trip from another transceiver. As already described, a uniform reference point is defined in the data frame at which the response time generation begins

0330If, as already described, the time of the frame synchronization is used for starting the counter module 160, the value CNT_reply for the response time interval can be shortened accordingly so that the sending of the subsequent data frame can begin in good time.

0331In any case, the decoding and checking of the received request data frame must be completed before the start of the transmission of the subsequent data frame. This is guaranteed by adequate dimensioning of the response time and the use of correspondingly fast decoding and test circuits. If the test was successful, and the counter module 160 signals the FRAME-CODEC module 162 that the response time interval has elapsed, a subsequent data frame is generated as a sequence of digital pulses.

0332The synchronization with the distance calculation unit takes place via the control connections Command 166 and Status 168. Via the Command control connection 166, the reception of a data frame is permitted and the generation of subsequent data frames is activated. The status control connection 168 signals the distance calculation unit that a data frame has been received and that if it has been checked successfully, a subsequent data frame has been sent.

0333In the present implementation, the module FRAME-CODEC 162 and the counter module 160 are supplied by a common clock signal CK and thus work synchronously.

0334The following explains in more detail how the described circuit improves the resolution of the generation of the response time interval by measuring and taking into account a scanning error. A pulse (a) detected by an analog receiving module (RX) 170 is sampled in an RXDH module 174 with a clock CKH. The sampling error corresponds on average to half the period of the clock applied to the CKH. Scanning the detected and sampled pulse (b) in the RXD module 176 results in a further, but substantially larger, temporal error, since the clock CK has a significantly longer period than the clock CKH. By measuring and considering this time, a better resolution of the actual response time interval is achieved. In practice, clock frequencies of approx. 100 200 MHz with an accuracy of ± 200 ppm is sufficient, since this precision is sufficient due to the special multipath method of the present invention. The resolution can be further increased by the dithering and averaging methods described above

0335As in the embodiment of the <figref idref="f0011">Fig. 18</figref> there are two design variants when realizing the measurement of the scanning error. In a first embodiment variant, a second counter module (CNTH) 178 is started by a pulse (b) sampled with the clock CKH via a connection 180. The received pulse (c) sampled and delayed with the clock CK causes the second counter module (CNTH) 178 to be stopped via a connection 182, the count value of which remains unchanged on one after the stop<i>CNTH_Δreply</i> - Connection 184 is present

0336In a second alternative embodiment, the second counter module (CNTH) 178 is started by the sampled and delayed receive pulse (c) via a connection 182. A subsequent detected pulse (b) sampled with the clock CKH causes the second counter module (CNTH) 178 to be stopped via a connection 180, the count value of which, after the stop, is likewise unchanged on one<i>CNTH</i>_{Δ<i>reply</i>} - Connection 186 is present

0337The FRAME-CODEC 162 module can activate the measurement of the scanning error for a specific pulse or multiple pulses of a data frame or a specific position or in a specific time range of the data frame via a control connection 184. The control connection 184 additionally allows the second counter module 178 to be reset.

0338The synchronization with the distance calculation unit takes place during the generation of the response time with the control connections Command 166 and Status 168. In addition, the status connection 168 signals the presence and the validity of a new measured value for the scanning error CNTH_Δreply the response time T_reply. The calculation of the response time T_reply takes place from the output value CNTH_Δreply of the counter module, the value applied for the response time CNT_reply and the periods of the clock frequencies at CK and CKH, whereby additional circuit-related delays must be taken into account.

18th Implementation of averaging

0339<figref idref="f0013">Fig. 20</figref> shows a simplified block diagram of an embodiment of a transceiver with implemented averaging. In the figure, only the modules essential for averaging are shown.

0340Averaging is basically carried out by first adding a plurality of temporal errors measured with high resolution, which arise from the scanning of received pulses of a data frame in the FRAME-CODEC module 162, and then dividing by the number of added error values. The mean error value obtained in this way is used for a precise measurement of the round trip interval and for an exact determination of the response interval.

0341In the following description it is assumed that the transmitted data frames contain complementary chirp pulses. Averaging is carried out equally for the two complementary pulse types, i.e. an equal number of the respective pulse types is taken into account. The number of time errors to be added can be specified. The entire circuit is not very time-critical and can therefore be implemented inexpensively, since the addition only has to be carried out with the pulse frequency (max. 10 MHz).

0342The counter outputs are for time errors of detected pulses of a received data frame measured with high resolution <i>CNTH_Δround</i> 192 of the concentricity measurement (cf. <figref idref="f0011">Fig. 18</figref>) or <i>CNTH_Δreply</i> 186 of response time generation (cf. <figref idref="f0012">Fig. 19</figref>) used. Depending on the situation, either output 192 or output 186 is routed to a first input 200 of an adder 202. The result of the addition is written into a sum register 204 and is on a ∑<i>_CNTHΔround</i>/∑<i>_CNTHΔreply</i>- Output 206 can be read out as a value.

0343The availability of the value contained in the sum register 204 is indicated by the FRAME-CODEC module 162 via its status connection 168. The status information of the concentricity measurement and response time generation can be used for this.

0344The number of values ​​to be added is specified via a PULSECNT connection 208. The number of values ​​already taken into account is recorded via counters CNT1 210 and CNT2 212 and compared with the number to be taken into account in two comparators 214 and 216 according to the value at the PULSECNT connection. If the required number has not yet been reached, signals CPULSET1 and CPULSET2 form, via signal logic 218, a control signal (add) present at their output 220 for adding up new counter outputs <i>CNTH_Δround</i> or. <i>CNTH_Δreply</i> the runout time measurement or response time interval generation.

0345The signals CPULSET1 (11) and CPULSET2 (12) each correspond to two different complementary pulses detected and are delayed because of the counter outputs <i>CNTH_Δround</i> 192 and <i>CNTH_Δreply</i> 186 are only available for a certain time after the detection of the pulses.

0346The signals CPULSET1 and CPULSET2 are mutually exclusive and therefore do not occur simultaneously. Since the sum formation takes place anew for each data frame, the FRAME-CODEC module 162 must reset the sum register 204 and the counters 210 (CNT1) and 212 (CNT2) with a control signal (reset) via a control output 222 at the start of a new data frame.

0347A summation over the reception times of an equal number of the respective pulse types takes place by taking into account the respectively identical number of pulses via the counters CNT1 and CNT2. A NAND gate 224, at the inputs of which the outputs of the two comparators 214 and 216 are routed, indicates via a valid connection 226 whether the required number of complementary pulse types has been taken into account.

0348To calculate the round trip and response time intervals, the calculated sums must be on ∑<i>_CNTHΔround</i>/∑<i>_CNTHΔreply</i> - Output 206 must be divided beforehand by the number of added values. The corresponding calculation means are in<figref idref="f0013">Fig. 20</figref> not shown. They can be provided as a processing module in the transceiver or as an external module, for example in the form of a software module of a microcontroller externally connected to the transceiver. The calculation of the average time of receipt of the message frames, which are the basis of the round trip and response time, is carried out according to the following formulas:<maths id="math0052" num="Formel 44:"><math display="block"><mrow><mi mathvariant="normal">Δ</mi><mo>⁢</mo><msub><mi>T</mi><mi mathvariant="italic">roundAVG</mi></msub><mo>=</mo><mfrac><mrow><mn>1</mn></mrow><mrow><mn>2</mn><mo>⋅</mo><msub><mi>n</mi><mi mathvariant="italic">PULSECNT</mi></msub><mo>⋅</mo><msub><mrow><mi>f</mi></mrow><mrow><mi mathvariant="italic">CKH</mi><mo>⁢</mo><mn>2</mn></mrow></msub></mrow></mfrac><mrow><msub><mrow><mo>∑</mo></mrow><mrow><mi mathvariant="italic">CNTH</mi><mrow><mi mathvariant="normal">Δ</mi></mrow><mi mathvariant="italic">round</mi></mrow></msub></mrow></mrow></math><img file="EP1815267B1_D0052.tif" /></maths><maths id="math0053" num="Formel 45:"><math display="block"><mrow><mi mathvariant="normal">Δ</mi><mo>⁢</mo><msub><mi>T</mi><mi mathvariant="italic">replyAVG</mi></msub><mo>=</mo><mfrac><mrow><mn>1</mn></mrow><mrow><mn>2</mn><mo>⋅</mo><msub><mi>n</mi><mi mathvariant="italic">PULSECNT</mi></msub><mo>⋅</mo><msub><mrow><mi>f</mi></mrow><mrow><mi mathvariant="italic">CKH</mi><mo>⁢</mo><mn>2</mn></mrow></msub></mrow></mfrac><mrow><msub><mrow><mo>∑</mo></mrow><mrow><mi mathvariant="italic">CNTH</mi><mrow><mi mathvariant="normal">Δ</mi></mrow><mi mathvariant="italic">reply</mi></mrow></msub></mrow></mrow></math><img file="EP1815267B1_D0053.tif" /></maths>

19th Calculation of the runout and response time intervals

0349With reference to the <figref idref="f0011 f0012 f0013">18 to 20</figref> the following explains how runout and response time intervals are calculated.

0350The round trip intervals are calculated with the help of the counter output <i>CNT_round</i> at the output 164 of the counter 160 and the averaged sampling error of the round trip time Δ<i>T_roundAVG</i>, with circuit-related delays in the transmitter and receiver circuits, <i>T_TX</i> and <i>T_RX</i>, must also be taken into account. Depending on the implementation variant used, the averaged sampling error of the concentricity Δ<i>T_roundAVG</i> Either add or subtract using the following formula. <maths id="math0054" num="Formel 46:"><math display="block"><mrow><msub><mi>T</mi><mi mathvariant="italic">round</mi></msub><mo>=</mo><mfrac><mrow><mn>1</mn></mrow><mrow><msub><mi>f</mi><mi mathvariant="italic">CK</mi></msub></mrow></mfrac><mo>=</mo><msub><mi mathvariant="italic">CNT</mi><mi mathvariant="italic">round</mi></msub><mo>+</mo><mi mathvariant="italic">k</mi><mrow><mi mathvariant="normal">Δ</mi></mrow><msub><mi mathvariant="italic">T</mi><mi mathvariant="italic">roundAVG</mi></msub><mo>+</mo><msub><mi mathvariant="italic">T</mi><mi mathvariant="italic">TX</mi></msub><mo>+</mo><msub><mi mathvariant="italic">T</mi><mi mathvariant="italic">RX</mi></msub><mo>;</mo><mrow><mspace width="1em" /></mrow><mi>k</mi><mo>=</mo><mo>-</mo><mn>1</mn><mo>,</mo><mn>1</mn></mrow></math><img file="EP1815267B1_D0054.tif" /></maths>

0351The response time intervals are calculated using the value for <i>CNT_reply</i> at port 190 and the averaged sampling error of the response time <i>ΔT_replyAVG</i>, the circuit-related delays of the transmitter and receiver circuits, <i>T_TX</i> and <i>T</i>_<i>RX</i>. must also be taken into account. Depending on the implementation variant used, the averaged sampling error of the response time Δ<i>T_replyAVG</i> be added or subtracted. <maths id="math0055" num="Formel 47:"><math display="block"><mrow><msub><mi>T</mi><mi mathvariant="italic">reply</mi></msub><mo>=</mo><mfrac><mrow><mn>1</mn></mrow><mrow><msub><mi>f</mi><mi mathvariant="italic">CK</mi></msub></mrow></mfrac><mo>=</mo><msub><mi mathvariant="italic">CNT</mi><mi mathvariant="italic">reply</mi></msub><mo>+</mo><mi mathvariant="italic">k</mi><mrow><mi mathvariant="normal">Δ</mi></mrow><msub><mi mathvariant="italic">T</mi><mi mathvariant="italic">replyAVG</mi></msub><mo>+</mo><msub><mi mathvariant="italic">T</mi><mi mathvariant="italic">TX</mi></msub><mo>+</mo><msub><mi mathvariant="italic">T</mi><mi mathvariant="italic">RX</mi></msub><mo>;</mo><mrow><mspace width="1em" /></mrow><mi>k</mi><mo>=</mo><mo>-</mo><mn>1</mn><mo>,</mo><mn>1</mn></mrow></math><img file="EP1815267B1_D0055.tif" /></maths>