Method and device for the photographic registration of vehicles

The invention relates to a method for imaging, in particular photographic registration of counter outdated vehicles by means of a fitted with an image pickup device Doppler radar speed measuring device, with which the vehicles are measured from the front and registered figurative, wherein during a measurement section after the entry of a vehicle into the measuring lobe a corresponding velocity measured value determined and if this exceeds a certain limit, the image pickup device is triggered, and the speed measured value is displayed in the recording.

From DE-PS 1,805,903 a process for the camera triggering at a Doppler radar speed measuring device is known in which the vehicles are measured from the rear and photographed, wherein the triggering of the camera is suppressed when the measured speed value is not unambiguously a particular vehicle can be assigned.

Since when measuring and photographing the outflowing traffic nurdasfehlbare vehicle, but not the link is idendifiziert, it is recently gone over to make either in addition to hold back or even without such a so-called front photograph what makes clear identification and the vehicle driver , A to suitable device is for example known from DE-PS 28 02 448th

So you will at the roadside either a speed measuring device in DE-PS type described 1,805,903 and coupled with this front photograph apparatus according to DE-PS 28 02 448 and missed the cars from behind and photographed her from behind and from the front, or using a single speed measuring device and misses and photographed the vehicles only from the front.

In the first case the system more expensive by the use of two cameras and it is also cumbersome and likely to be more suitable for stationary, not for mobile use.

In the second case arises from the requirement that the vehicle must be quickly photographed after his entrance into the measuring range of the radar, because otherwise it leaves the camera's field, the condition that the determination of the speed value takes place within a relatively short measurement section. Since the measurement is completed immediately after the provision of the measured value and triggered the camera, but with the vehicle is only at the beginning of the measuring range of the radar device, thus most of the Doppler signal generated during the passage of the vehicle through the measuring lobe remains unevaluated, whereby the measurement reliability is reduced.

For example, directly during or after the measurement takes place within the measuring range of the radar device overtaking not be detected because of the corresponding receptacle in a relatively narrow range several vehicles were ready and reliable assignment of the displayed measured value at a certain the vehicles shown is not possible , To avoid mismatches, must therefore be dispensed with relatively small distances to the evaluation of such recordings with several vehicles, but in today's heavy traffic, the proportion of such images that can not be evaluated, is relatively large.

The invention has the task for today preferred measurement arrangement to measure and photograph from the front, so the oncoming traffic, to increase the measurement reliability and to eliminate the non-evaluable recordings or reduce their number at least drastically.

This object is inventively achieved in that after triggering the image pickup apparatus further evaluated the Doppler signal generated by a designated as Verification route hereinafter stretch the measuring lobe at the passage of the vehicle and the result of this evaluation is used for an accrediting of speed reading.

The inventive method thus makes it possible, despite the necessary measurement and photograph of the vehicle at the beginning of the measuring range of the radar, the evaluation of the whole generated during transit through the measuring lobe Doppler signal by the initial speed measured value is checked on the verification link. It also overtaking can be detected in the field of measuring lobe in particular.

The invention further relates to a device for carrying out said method, comprising a Doppler-radar speed measuring device with a computer for evaluating the Doppler signals and with a one Dateneinblende unit having camera, which by the computer with a camera triggering, a film transport and a data Einblendesignal is driven.

The inventive device is characterized in that the computer is configured to be reviewed after delivery of the camera trigger signal the speed reading of appropriate vehicle on the verification route and based on the result of an accrediting either the insertion of speed reading or cancellation of the measurement and then he it further transport of the film triggered.

The fact that the film is not transported by the shutter release immediately, the possibility of an accrediting the speed measured value is created during the verification route, which then leads to a confirmation of the speed measured value or its cancellation. Through these measures a measurement reliability is achieved as in the measurement and photograph from behind, towards the latter, but results in the additional advantage of the safe and unambiguous identification of the driver in the monitoring of oncoming traffic despite measurement and photograph from the front.

Hereinafter the invention using an exemplary embodiment and of the drawings is explained in detail; show it:<ul><li>FIG. 1 shows a schematic representation of the geometry of the formation of an inventive device on a road with two lanes in each direction,</li><li>Fig. 2, 3 are each a diagram of a specific traffic situation with two vehicles in the measuring leg in the upper half and the corresponding speed chart in the lower half,</li><li>Fig. 4 is a block diagram of the inventive device, and</li><li>FIGS. 5a, 5b, a flow chart of the microcomputer of the device of FIG. 4 program.</li></ul>

Fig. 1 shows two traces S₁ and S₂ a road, for example, one half of a highway, with a moving in the direction indicated by arrow F vehicle on the fast S₂, Laterally, the standard gauge S₁ is a radar device installed with camera R + K, which monitors oncoming traffic. The radar transmits the hatched drawn measuring lobe M from the camera has the opening angle a. Radar and camera R + K can be installed in a vehicle or placed on a tripod. The measuring angle to the direction of travel is about 22 °.

Once the vehicle F as shown in the figure with its front enters into the measuring lobe M, it reflects the radar radiation and is generated in the radar unit in a known manner by superposition of a portion of the transmission energy with the light reflected from the vehicle receiving power, an electric oscillation, the Doppler signal whose frequency, the Doppler frequency of the relative speed between the vehicle and the radar device is proportional. These operations are described in DE-PS 1,805,903 to which reference is made herewith described in detail.

Once the Doppler frequency has stabilized after the entrance of the vehicle F in the measuring lobe M during a certain measurement section, a speed measured value is determined similarly as in the process described in German Patent No. 1,805,903 method, the average of the stable during this particular section Doppler frequency and stored. As soon as this speed exceeds a preset limit value for the permissible maximum speed at the measuring site, the camera is triggered, and the vehicle is photographed from the front; the film is not transported.

Then the Doppler frequency is checked on their behavior over time compared to the previously stored speed reading out. For this, a related to this saved speed measurement tolerance range, for example ± 3% is determined and can be calculated from the speed measurement values, the certain path lengths correspond to which the vehicle travels F. It is a stretch, the so-called verification stretch of example 3 m length defined within which the Doppler frequency must not show any significant differences from the stored speed reading. As significant deviation an uninterrupted leaving the tolerance range during a certain limit length of for example 1 m-border route is defined. Lies beneath over- or undershooting of the tolerance range, as can occur in the measuring lobe at each measurement even without the presence of other vehicles are, however, tolerated and therefore do not lead to a cancellation of the measurement.

If no such significant deviations of the Doppler frequency from the stored speed reading occur during the verification path, then is derived from the fact that there are no other vehicles in the immediate vicinity of the appropriate vehicle F, so that the assignment of the speed measured value is saved to the previously photographed vehicle F. Only now the speed reading is displayed in the already-captured image. Subsequently, the film is advanced and the camera is ready for a new recording.

If during the verification distance at least a significant deviation of the Doppler frequency from the stored speed reading occurs, then there is a likelihood of the simultaneous presence of several vehicles in the measurement leg, whereby a reliable assignment of the speed measurement value to a certain of these vehicles is impossible. Therefore cancels the measurement after the verification path by the already-captured image instead of speed reading a special Annullationsanzeige, for example, two lines - is displayed. Subsequently, the film is advanced and the camera is ready for a new recording.

These processes just described will now be explained with reference to two shown in the Figures 2 and 3 embodiments. The vehicles in the measurement lobe M are symbolized only by their front, their respective position for various time points t₁ to t₁₈ is located. Since the vehicles are traveling at different speeds, are in the two tracks S₁ and S₂ which correspond to the driven distances between the individual points in time intervals of different size, or in other words, the one vehicle, wherein the distances between the individual points in time are larger, runs faster. In Figs. 2 and 3, the diagram of the driving situation and is shown the corresponding velocity diagram in the lower half, respectively in the upper half.

FIG. 2 shows in the lane S₂ a slower vehicle F₂Which from a faster vehicle F₁ Tracking S₁ is obsolete right. The vehicle F₂ moves at time t₁ first in the measuring lobe M and triggers the measurement, the vehicle F₁ only arrives at time t₃ in the measurement leg. During the time interval t₂ to t₃Which will correspond to the length of the measuring section A, the Doppler frequency remains stable, at time t₃ the following operations take place:<ul><li>- Determination of speed reading and storing it (it is assumed that the speed limit at 60 km / h lawn)</li><li>- Definition of tolerance C,</li><li>- Determining the length of a significant deviation,</li><li>- Determining the length of the verification distance B,</li><li>- Release of the camera.</li></ul>

Also to Zeitpunktt₃ the vehicle F₁ - A higher speed than the vehicle F_z - Into the measuring lobe M. Therefore, the Doppler frequency leaves soon after the tolerance range C, and not just temporarily, but over the entire remaining length of the verification distance 8. It is therefore a significant deviation of the Doppler frequency from the stored speed reading within the verification route 8 determined. Therefore, after the end of the verification distance at time t₆ in the already-captured a Annullationszeichen - appears and then the film is advanced. On the recording you will be the two vehicles F₁ and F₂ can realize the mutual distance is so small that a reading assignment is not possible.

In the examples shown in Fig. 3 driving two vehicles F₁ and F₂ the same time t₁ in the measuring lobe M and while the vehicle F₁ at a speed of about 90 km / h, the vehicle F₂ with such of about 60 km / h. The vehicle F₁ covers the vehicle F₂ completely, so that the Doppler frequency immediately to the value of the vehicle F₁ increases and remains at this value until the vehicle F₁ with his tail t shortly after time_8th extends from the measuring lobe M. Although then takes the Doppler frequency a value corresponding to the speed of the slower vehicle F₂ to which, however, the successful measurement and registration of the vehicle F₁ Tracking S₁ not prevented.

The Doppler frequency reached at the time t_a a value from which they t until the time_bOn which the measuring section A is completed, not differs significantly, so that during the measurement path A due to the average value of a reliable speed reading can be formed. This metric is now a tolerance range C, the length of a significant deviation and the length of the verification distance B are determined and it is also the time t_b after determining the speed reading the camera triggered the film but not transported. Since the speed measurement value is greater than the example of FIG. 2, also, the tolerance range C is larger and the time in which the measurement and the verification section A or B to be passed, is correspondingly shorter.

Since the slower vehicle F₂ remains covered using the verification section 8 completely, occur no significant variations of the Doppler frequency from the stored speed value during the corresponding period. Therefore, the speed reading is at the end of the verification distance at time t, 90 km / h are displayed in the already-captured and then transported to the film.

The recording can also be evaluated properly, although it two vehicles F₁ and F₂ can be seen. After all, the fact that a speed reading and no Annullationsanzeige is displayed, proving that the rear vehicle F₂ is not relevant have appeared in the measurement. Because when the vehicle F₂ would have gone faster, it would affect the Doppler frequency during the verification path and it would have occurred significant deviations so that a Annullationsanzeige would have been displayed.

Both in FIGS. 2 and 3 traffic situations depicted are merely examples to explain the function and operation of the inventive process. There are of course many other traffic situations might arise in which the inventive method can also be applied particularly beneficial. The terms used in the description of camera and film are not to be understood that the described method would be limited to today conventional photographic films and cameras, but rather denote any conceivable recording and recording device and any suitably qualified media. So you could, for example, also use electronic video cameras and tapes or discs.

In FIG. 4 is 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 these radiation components to the antenna 3rd This reflected radiation components are compared to the originally radiated from the antenna 3 is displaced by an amount that is proportional to the speed which 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 arrives a small part of the generated from the microwave oscillator 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 11 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) and an input / output stage (1/0) 17 (eg INTEL 8255), all of which are connected by a bus 18 for transferring data, addresses and control signals ,

As to the 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

This program will now be described with reference to the flow chart shown in Figures 5a and 5b:

A measuring process is initiated in accordance with FIG. 5a with the detection of the entrance of a vehicle F in the measuring lobe M (Fig. 1). This entry can be determined by the arrival of a number of level changes in the digital signal (input timer 11, Fig. 4) with a minimum frequency after a period without change of level. After detection of the entrance of the Doppler frequency to be constant is checked, and after a certain route with sufficiently constant Doppler frequency, the Doppler frequency is calculated on this range of speed measuring values ​​due to the average value.

If this is below the speed limit, then no picture is taken and maintained until detection of the entrance to the next vehicle. About Rising of reading the speed limit, then the camera is triggered immediately and are then required to carry out the verification values ​​calculated, namely the tolerance range, the length of a significant deviation and the length of the verification distance.

The verification is shown in Figure 5b separately. At the beginning of the verification is a timer in 11 (FIG. 4) included counter to what measure elapsed length of the verification distance, started. Subsequently, it is checked whether the last measured Doppler period is within the specified tolerance range. If this is the case, then thereto is interrogated the length of the route counter whether the verification route has already elapsed. If this is not the case, then the next Doppler period is checked to determine whether it is within the tolerance range. If even this is within the tolerance range, then turn the track length counter is queried, and so on. (Fig. 5a) If the Doppler frequency over the entire route verification within the tolerance range, then the verification is successfully completed at the end of this route and there is a return to the main program instead.

However, once a Doppler period with a length is measured outside the tolerance range, the program branches to a lateral branch. Here in the timer 11 (FIG. 4) is started first contained Ausreisserlängenzähler, of. The length of the newly detected "outlier", ie the period during which the Doppler frequency is outside the tolerance range, to measure Subsequently, the length of the next Doppler period is measured. If even this is out of tolerance, then the Ausreisserlängenzähler is queried. If the current outlier not yet reached the length of a significant deviation, then the length of the next period is measured Doppler.

This process repeats until either a Doppler period with a length is measured within the tolerance range, or the Ausreisserlängenzähler reached the level of a significant deviation. In the first case (Doppler frequency again within the tolerance range) the Ausreisserlängenzähler (Fig. 5a) is set to zero and again jumped to the first program loop, in the second case (Ausreisserlänge is significant) is finished verification unsuccessful and the main program jumps back.

In the main program (FIG. 5) in the case of a passed verification of speed reading in the Dateneinblende device D (Fig. 4) transmitted and output the Einblendesignal. In the case of a failed verification is the Annullationszeichen - transferred to Dateneinblende device and also output the Einblendesignal. Finally, the camera K (Fig. 4) leave the film transport signal and then waits for the detection of the entrance to the next vehicle.