Method and apparatus for monitoring the speed of vehicles using a Doppler radar speed measuring device, and application of the method.

The invention relates to a method for monitoring the speed of vehicles by means of a Doppler radar speed measuring device, which passes over the to be monitored road with a radar measuring lobe, comprising the steps of:<ul><li>a determination of a first speed measurement value by entering a vehicle into the measuring lobe.</li><li>b. subsequent conversion examination of the first speed measurement value to significant deviations over a distance called the verification hereinafter stretch in the measuring lobe;</li><li>c. Registration of the vehicle in question in exceeding of a certain limit by the first speed reading.</li></ul>

Such methods are 662,660 known from DE-PS 1,805,903 for monitoring the effluent and from the CH-PS to surveil chung of oncoming traffic, the registry respectively photographically, from behind or from the front is done. Practical experience has shown that it always happens that false measurements are triggered by so-called multiple reflections.

Multiple reflections are measurements in which the radar beam hits the moving object more than once, and thus experiences a corresponding multiple Doppler shift of the radar frequency. They occur only when the front or the rear of a vehicle are acted upon by the radar beam. When the radar beam (eg Brükkenpfeiler) deflected and reflected by the latter via the vehicle rear to the radar device, for example, from the rear of a vehicle against an effluent orstfesten reflector, then twice the speed measured value is measured.

It would be obvious to eliminate the multiple reflections in that one does not take into account integer multiples and fractions of the speed reading. But here would multiple reflections on moving objects, for example, at the front of the measuring object oncoming truck, not recognized as such, since the speeds of the two vehicles involved would add, in this case, whereby the integer ratio of the velocity measurements would be disturbed.

A second obvious measure would be to try to suppress multiple reflections by the length of the verification distance. Even this solution is not practical, because the length of the verification distance is determined on the one hand by the speed reading and on the other hand can not be arbitrarily large. This means in other words that such a high-speed reading can be simulated by multiple reflection at a moving object that the verification route runs even before the side sections of the appropriate vehicle reflects the radar beam.

The invention provides a method will now be given, multiple reflections can not trigger false measurement in its application with probability bordering on certainty.

This object is achieved with the method mentioned by the following additional steps:<ul><li>D. Search for more speed measurements after completion of the verification;</li><li>E. Comparing each further speed measurement value to the first; and</li><li>f. Confirmation or cancellation of the measurement and / or registration, depending on the result of this comparison, which have a deviation of a further speed measurement value resulting from the first to the cancellation.</li></ul>

It is thus according to the verification practically started again a speed measurement values ​​and thereby found are compared with the first speed measurement value. This sichgestellt goes into an error caused by multiple reflections or possibly by an overtaking vehicle incorrect first speed reading as a false measurement.

The invention further relates to a device for carrying out said method, with a Doppler radar speed measuring device, with a computer for processing and analysis of Doppler signals with an operator panel with display, with a recording device and a Dateneinblende device which the computer with registration tone or a Dateneinblendesignal are driven.

The inventive device is characterized in that the delivery of Dateneinblendesignals after completion of the comparison of the other speed readings will be within the first speed reading.

The invention further relates to a use of said method for speed monitoring from a moving measuring vehicle.

This application is characterized by the following steps:<ul><li>a measurement of the airspeed of the measuring vehicle.</li><li>b: determining the speed readings over overtaking vehicles on the basis of the values ​​of the measuring vehicle's own speed and the relative speed of the appropriate vehicle;</li><li>c. subsequent repeated measuring the airspeed of the test vehicle; and</li><li>d. confirmation or cancellation of the measurement and / or registration on the basis of additional criteria, whether before or after the determination of the velocity measurements of adequate vehicle measured values ​​of the airspeed of the measuring vehicle match within a predetermined tolerance range or different.</li></ul>

Hereinafter the invention using an exemplary embodiment and of the drawings is explained in detail; it shows:<ul><li>Fig. 1 is a block diagram of an inventive device,</li><li>Fig. 2.3 for functional explanation each a diagram</li><li>Fig. 4-6 are flow charts of the computer of the apparatus of Fig. 1 program.</li></ul>

The method described below and the device used for its implementation serve whose speed exceeds the maximum authorized speed for monitoring the speed of vehicles and the figurative, in particular special photographic registration of those vehicles. In this case, both the to-and the outflowing traffic to be monitored, which is possible with the same device even in mixed operation. For further explanation of the technological Hintergunds made to DE-PS 1,805,903 (= US Patent No. 3,754,253) and the CH-PS 662 660 (= US Patent No. 4,717,915) refer to the disclosure incorporated herein by reference ,

In Fig. 1 a block diagram of an apparatus for carrying out the inventive method is illustrated. A microwave oscillator 1 generates a microwave signal which is fed via a hollow conductor 2 of an antenna 3 and focused by this radiated. As soon as a vehicle passes through the vicinity of the antenna 3 are reflected by this radiation components to the antenna 3rd These reflected radiation portions are compared to the originally radiated from the antenna 3 is displaced by an amount which is proportional to the speed of the vehicle. This phenomenon is called the Doppler effect and the frequency shift as a Doppler frequency.

The received by the antenna 3 are reflected radiation components of a mixer 4 via the waveguide 2, to which also a small proportion of the passes from the micro wave generated lenoszillators original microwave signal. The two mentioned signals are mixed in the mixer 4 and the resulting mixing product, a low frequency alternating voltage with the Doppler frequency, is applied to the input of an amplifier fifth Its output signal is the input of a filter 6 is supplied, which is permeable only to the interest for further evaluation of the spectrum, which is the speed the measuring range of the radar belonging Dopplerspektralkomponente. Thus, the shares of the noise voltage is outside of the passband of the filter 6 eliminated, so that the signal-to-noise ratio is improved. The signal appearing at the output of filter 6 is then digitized by a Schmitt trigger. 7

That at the output of the Schmitt trigger 7 removable digital signal contains all the useful information about the speed of the radar beam in the moving objects. It is to the input of belonging to a microcomputer 10 timer 11 (for example, INTEL 8253) performed in which the time intervals between the logical changes in the digitized Doppler signal sequentially measured and are supplied to the microcomputer 10 for analysis. The microcomputer contains apart from the timer 11 or a central processing unit (CPU) 12 (such as Intel 8085) with a quartz 13 which outputs to the timer 11 via a line 14 a clock signal, an erasable programmable read only memory (EPROM) 15 (for example, INTEL 2764 ), a data random access memory (RAM) 16 (eg INTEL 8185), a first input / output stage (I / O) 17 (eg INTEL 8255) and a second input / output stage (I / 0) 19, all of which by a busbar 18 are connected for transferring data, address and control signals.

As to the second input / output stage 19 is an operation part 20 is connected with display. As to the first input / output stage 17 is a recording camera K driven by a Dateneinblende device D. The camera K is connected via lines 8 and 9 for the camera trigger or the film transport signal and the Dateneinblende device D is connected by a busbar 19 for the to be inserted data and a line 20 for the data-fade-in signal to the input / output level 17. The data memory 16 is used for temporary storage of variable data and intermediate results and programmable read only memory 15 contains in binary code, the program of the microcomputer 10th

The operation of the apparatus shown in Fig. 1 will now be described with reference to FIGS. 2 and 3, wherein Fig. 2 is a diagram of the measurement process of a valid measurement and Fig. 3 shows a diagram of the measuring sequence of three measurements canceled. In the diagrams, the ordinate represents the velocity v and to the Absizze t is the time or the distance corresponding plotted s.

Once a vehicle designated below in the as measuring lobe of the antenna 3 (Fig. 1) emitted radiation beam enters, it reflects the radar radiation and it is in the radar device in a known manner by the superposition of a portion of the transmission power with the light reflected from the vehicle receiving power an electrical vibration generating the Doppler signal. Its frequency, the Doppler frequency, the relative speed between the vehicle and the radar device is proportional. These operations are described in detail in the already erwähten DE-PS 1,805,903.

In the entrance phase "waiting" the radar on the vehicle until the Doppler frequency and thus the speed has somewhat stabilized, which is the case at time t1 at which the detection is the driveway. Subsequently, a speed measured value is in the time interval t1 to t2, which corresponds to the length of a measurement path A maximum of two meters, for example, v * determined. For this purpose, a piece with constant Doppler periods is searched for within the measurement path A. Each new Doppler period is compared to the current average of the last example 4 Doppler periods and accepted only if it differs from this by more than a predetermined tolerance, for example, 3%. Then, at time t2 over a certain number of, for example 12 consecutive and said consistency criterion is fulfilled Doppler periods of funds formed from the value and velocity measurement value v * is calculated.

At the same time run at the time t2 following actions occur: - Display of the speed measurement value v * at the operation part 20; * Plus / minus 3% and calculation of time values, the certain distance traveled by the vehicle travel distances corresponding to establishing a on the Speed ​​Reading v * related tolerance range C of example v -; - Determining the length of the so-called verification distance B of example, three meters in length within which the Doppler frequency must not show any significant differences from the stored Speed ​​Reading v *; - Establishing a limit length of one meter, for example as a criterion for determining whether a significant difference exists. Definition: Significant deviation is an uninterrupted leave the tolerance range C by the Doppler frequency over a limit length-border route.

In monitoring the effluent traffic at the time t2 expires, no further operation in monitoring the oncoming traffic will be two additional operations: - Comparison of the speed measurement value v * with a stored limit value for the permissible maximum speed at the measuring site. - In the event of transgression of this limit by v *, triggering a photograph of the vehicle concerned (but no data flash and no further transport of the film).

Now takes place along the length of the verification distance B up to the time t3, the verification of the speed measurement value v *. In Fig. 2 a signal deviation is registered in this interval, although, in which the Doppler frequency is outside the tolerance range C; it is however no significant difference, since the length of the deviation is far below the limit length. Thus, at the time t3 of the assessment of that velocity measurement value v * has passed the verification. The verification of the speed measurement value v * is done in any event, and even if v * is less than the limit for the permitted maximum speed at the measuring site.

When measuring the traffic flowing out will now if v * is greater than said limiting value, triggers a photograph.

After time t3, a hereinafter referred to as "check" designated more measurement verification, by which mainly caused by multiple reflections of the radar beam (see background section) triggered false measurements carried recognize who are the. When an accrediting check will determine whether further speed readings occur until the exit of the vehicle from the radar lobe, and whether this possibly * be different from v. If such deviating measured value is found, then the measurement and a possibly triggered Photography is canceled. If no deviating measured value is found and thus the velocity measurement value v * confirmed, will appear in therefore any triggered Photography of Speed ​​Reading v * and released the film transport.

When an accrediting check is after the time t3 after a with the measured value determination (measuring distance A) comparable processes, but with reduced stability criteria (eg tolerance of Doppler periods for running average 6% instead of 3%, number of entries in the sum of the Doppler periods 8 instead of 12) searched for another speed reading. The constancy criteria be reduced in order to reliably detect different speed values, even if they are very short. If no other speed reading more can be found, so this enstpricht leaving the radar beam and the measurement is valid. If another speed reading found, a comparison is made with the Speed ​​Reading v *; are both measured values ​​within the tolerance limit equal, then a next check is started by either an aberrant reading or no longer found. In a different reading occurs, the measurement is canceled.

In Fig. 2, a deviation is detected at time t4, which is then checked to time t5. Since it is here to exit the vehicle from the radar lobe, the Doppler signal is steadily decreasing and it can form no more reading. Therefore, at the time t5, the speed reading is v * appears in the photograph, and transported to the film. 6t At the time finally has the vehicle left the radar lobe, which is indicated by a gap in the Doppler signal.

In Fig. 3, three cases are shown where there is a cancellation of the measurement.<ul><li>Case a: During the measurement path no measured value is found, so that at the time t2 no Speed ​​Reading v * can be calculated. The measurement is aborted.</li><li>Case b: during the verification (line B) occurs a deviation of more than 3% over a distance of more than one meter. Therefore, the verification is not passed, and the measurement will be canceled. It is triggered at the time t3 in runoff traffic no photo and oncoming traffic a Annullationszeichen appears in the already initiated at time t2 Photography.</li><li>Case c: The verification was passed, which means that in each case a photograph has been triggered. When an accrediting check a deviation is detected. Its an accrediting between t4 and t5 results in a further speed measurement value is not equal v *, so that at the time t5, a cancellation of the measurement by means of a corresponding insertion Annullationszeichens done in the photograph.</li></ul>

Fig. 4 shows a flow diagram of the measurement program, which is in principle coincides with that according to the 662 660 CH-PS and therefore not explained in detail. Differences are, inter alia, that at the beginning of the measurement, a Doppler signal gap is awaited (to ensure that no one already befindliches in the radar lobe vehicle again adequate, and that each vehicle is measured shortly after entering the radar beam), and that a distinction carried by runoff and oncoming traffic. The main difference lies in the check sub-routine, whose flow chart is shown in Fig. 5. The subroutine verification corresponds to that of the CH-PS 662 660 and is not shown here.

According to FIG. 5 begins the subroutine check with the preparation for the measurement, the counter for the distance, the sum of the Doppler period and the number of entries are set to zero. Also carried out the requirement that an average over four Doppler period is appropriate.

Then begins the search for new Doppler periods; if any are found, they are compared to the mean. If they agree with this within a predetermined tolerance, then the new Doppler periods are added to the current total and it is the number of entries increments. Do the new Doppler periods not to mean, then sum and number of entries are made equal to zero, and it is then for both cases, a new running average formed.

Subsequently, it is checked whether the required number Z of entries is reached. If not, it is checked whether a specific route has expired, for example, two meters. If so, there is an exit and the measurement is valid; if not, turn the flow starts immediately after the preparation of the measure.

If the number Z of the required entries is reached, a new speed reading vi is calculated and determined with the original at the time t2 (FIG. 2) Speed ​​Reading v * compared. If both. Within the tolerance range agreed, the process starts again in the preparation of measurement If the two VELOCITY keitsmesswerte from each other, then the measurement is prized as invalid. The findings "Measurement invalid" or "Measurement valid" finds a return instead of the measurement program.

In the embodiment described so far is tacitly assumed that the radar is during measurement and does not move. If the monitoring is performed by means of radar measurement of a moving vehicle (so-called moving radar), then a flow takes place according to the flow chart shown in Fig. 6. The vehicle used in the measurement must be equipped with a calibrated speedometer to measure the airspeed.

In so-called tacho operating constantly airspeed E1 measured and displayed, and it is continuously checked whether a vehicle is in the radar beam. If this is the case, then a radar measurement according to the measurement program of Fig. 4, but with the difference that is used an additional criterion for assessing the validity of the measure by which a valid by the measuring program of Fig. 4 ago se measurement can still be canceled.

Namely, the airspeed of the measuring vehicle is again measured by the radar measurement. Where the case measured value E2 within a tolerance with E1 match, then there is no objection to the just made radar measurement and it in turn starts the tachometer operation. However, divergences between E2 of E1, then the radar measurement is canceled.