Testing device for testing distance sensors operating using electromagnetic waves

Abstract

A test device (1) for testing a distance sensor (2) operating with electromagnetic waves in the form of at least one time-coherent and time-limited sensor signal, the test device (1) comprising: RX ) and a receiving element (3) for receiving an electromagnetic free space wave as an electromagnetic output signal (S TX ) and a radiating element (4) for radiating a received signal (S RX ) or received signal (S RX ) is derived from the received signal (S' RX ) with a specifiable time delay (t delay,soll ) through a signal processing unit (5) to produce a time-delayed signal (S delay ), and the time-delayed signal (S delay ) or the time-delayed signal (S delay ) is a time-delayed signal (S' delay ) is the output signal (S TX ) via a radiating element (4). A corresponding method (10) for operating such an inspection device (1) is also claimed. RX ) or the received sensor signal (S RX ) is derived from the received time-consistent and time-limited sensor signal (S′ RX ) at the start of the delay step (6) and thus the received time-limited sensor signal (S RX ) processing begins with a specified time delay (t delay,soll ) even during the delay step (6) and thus the received sensor signal (S RX ) or the received sensor signal (S RX ) is derived from the received sensor signal (S' RX ) during continuous processing, the specified time delay (t delay,soll ) is changed, the constant actuation time delay (t delay,work) is used as the fully processed and time delayed sensor signal (S delay ) is generated to avoid inconsistencies in the simulated reflected signal.

Description

[Technical field]

[0001] The invention relates to an inspection device for testing distance sensors operating with electromagnetic waves in the form of at least one time-coherent and time-limited sensor signal, the inspection device comprising a receiving element for receiving electromagnetic free space waves as a received signal and a radiating element for radiating an electromagnetic output signal, wherein during a simulation operation the received signal or a received signal derived therefrom is fed through a signal processing unit with a specifiable time delay, whereby it is time-delayed to a time-delayed signal as a simulated reflected signal, and the time-delayed signal or a time-delayed signal derived therefrom is radiated through the radiating element as an output signal. The invention further relates to a method for operating the inspection device as described above. [Background technology]

[0002] The above-mentioned inspection devices for testing distance sensors and methods for operating such inspection devices are known from various technical fields and application areas, for example from the field of control device development and control device testing, especially in the automotive field, see, for example, WO 2020 / 165191. Another application area is end-of-line test benches, i.e. devices used here to test distance sensors, for testing products at the end of the production line. In this case, the testing of distance sensors operating with electromagnetic waves is in question. In the automotive field, radar sensors are used overwhelmingly. However, in principle, it is also possible to test distance sensors operating in other frequency ranges of electromagnetic waves, such as, for example, the visible light range, or distance sensors (e.g. LiDAR) operating with electromagnetic radiation sources emitting electromagnetic waves with a long coherence length, as for example in laser applications.

[0003] The inspection device mentioned at the beginning makes it possible to pose an object at practically any distance to the distance sensor to be tested. Distance sensors of the type considered here basically work in such a way that electromagnetic waves emitted by them are reflected by objects within the radiation range of the distance sensor, which receives the reflected electromagnetic waves and determines the distance to the object from the propagation time of the electromagnetic waves. The determination of the signal propagation time can be performed directly (measuring the time-of-flight), but is more often performed indirectly through a sophisticated signal evaluation. In the first case, it is often operated with very short sensor signals, i.e. with pulses, while in the latter case, a transmission signal that is extended in a way that is distinguishable in time is often used. As an example, a frequency-modulated continuous wave signal may be mentioned here.

[0004] To test a distance sensor, an inspection device is positioned within the radiating range of the distance sensor, the inspection device receives the free space waves emitted from the distance sensor, delays the received signal by a signal processing unit of the inspection device according to a specified time delay, and then re-radiates the time-delayed signal in the direction of the distance sensor to be tested via a radiating element of the inspection device, thereby creating an impression in the distance sensor of an object that has been moved away according to the set time delay.

[0005] Distance sensors operating with time-coherent and time-limited sensor signals are considered here. In the prior art, it is known to realize such signals, for example, as chirp signals ("chirp" for short), i.e. as sinusoidal signals with a frequency that varies depending on time. It is also conceivable to realize them with other forms of modulation. Many distance sensors emit a number of such time-limited chirps, for example 128 or 256, with short transmission pauses between the chirps. Such a sequence of several closely spaced successive chirps is followed by a relatively long transmission pause for signal processing. A chirp sequence including a transmission pause is also called a frame. The frames are currently operated with a frame repetition frequency of typically several tens of Hertz during sustained measurements. The distance sensor to be tested is able to obtain a distance measurement from each individual emitted chirp transmission signal. This is done by mixing the further transmitted part of the chirp signal with the part of the chirp signal that has been reflected and already received again. The signal propagation time and thus the distance information is obtained from the frequency of the mixed signal. If the object reflecting the transmitted chirp signal has a radial component of motion relative to the range sensor, the mixed signal of multiple successive chirps will have phase differences which can be determined and from which velocity information regarding the radial component of motion can and is obtained directly.

[0006] When using the above-mentioned inspection device for testing distance sensors, in particular when dynamic simulation operations are performed using variable specified values ​​for the specifiable time delays, it has been noticed that, for example, a number of velocities varying within a wide range of numerical values ​​are assigned to one identified object, which leads to repeated signal evaluations on the part of the distance sensor that contain apparent errors, in particular with regard to the radial velocity of the simulated object. Summary of the Invention [Problem to be solved by the invention]

[0007] The object of the invention is to configure the above-mentioned test device and the above-mentioned method in such a way that the error situations known from the prior art are avoided. [Means for solving the problem]

[0008] In order to solve the problem on which the present invention is based, it was first necessary to recognize that the origin of the above-mentioned apparent error evaluation, which is observed, in particular with respect to the speed signal, of the distance sensor to be tested, originates from the testing device. It was recognized that the apparent error evaluation in the distance sensor can (but does not necessarily) always occur when the signal processing unit processes the received time-consistent and time-limited sensor signal with a first specified time delay to generate a time-delayed sensor signal, and during this processing process another time delay is specified and directly factored into the delay process that is still ongoing. It is not uncommon that the direct consideration of the changed specified time delay leads to discontinuities in the course of the delayed sensor signal, which then end up being present in the distance sensor as a simulated reflected sensor signal with discontinuities, leading to an evaluation containing apparent errors. I say "apparently erroneous" because the evaluation is perfectly correct, but the underlying database is inconsistent: in a real situation, i.e. when detecting real moving objects, no discontinuities actually occur, because the distance from the real object cannot change abruptly.

[0009] In order to solve this problem, in the inspection device as mentioned at the beginning and in the method for operating such an inspection device as mentioned at the beginning, according to the invention, the received time-coherent and time-limited sensor signal or the received time-coherent and time-limited sensor signal derived from the received sensor signal is completely processed by the signal processing unit in a delay step by using a time delay specified at the start of the delay step and thus at the start of the processing of the received time-limited sensor signal as a constant operating time delay, even if the specified time delay is changed during the delay step and thus during the ongoing processing of the received sensor signal or the received sensor signal derived from the received sensor signal, to generate a time-delayed sensor signal.

[0010] The solution according to the invention consists in completing a delay step, once started, based on a specified specific time delay, with this time delay being maintained as a constant operating time delay, and even if a new specifiable time delay is set or specified in the middle, the sensor signal to be delayed is thus processed completely with one uniform operating time delay. It has been found that if the inspection device is configured as described above or if it is operated using a correspondingly configured method, the problems in evaluating the simulated reflected signal at the distance sensor can be substantially completely solved.

[0011] In this document, a conceptual distinction is always made between a received signal and a received signal derived from the received signal. The received signal itself is based on a free space wave received by a receiving element of the testing device. If the received signal undergoes further signal processing before being forwarded to a signal processing unit, then strictly speaking it is no longer the received signal itself, but a received signal derived from the received signal. This is the case, for example, when the received signal is down-converted to a lower intermediate frequency, which reduces the requirements for the technical realization of the signal transmission path and also the requirements for the speed of the signal processing. In line with the meaning, this naturally also applies to a time-delayed signal or to a time-delayed signal derived from a time-delayed signal, but this does not require further explanation.

[0012] A preferred embodiment of the inspection device is characterized in that in the delay step, the fact that the received sensor signal or the received sensor signal derived therefrom is in continuous processing is detected by the signal processing unit determining a signal level or a signal power of the received signal or the received signal derived therefrom and deducing that the received sensor signal or the received sensor signal derived therefrom is still in continuous processing if the determined signal level or the determined signal power is above a specified active threshold for the signal level or the signal power. The active threshold for the signal level or the signal power should be selected in such a way that it is possible to clearly distinguish the signal noise present in the operating environment of the inspection device, which can never be completely avoided, from the currently useful signal.

[0013] In this connection, a further preferred embodiment of the test device is characterized in that the signal processing unit detects the start of the delay step and thus the start of the continuous processing of the received sensor signal or of a received sensor signal derived therefrom if the determined signal level or determined signal power exceeds a specified active threshold for the signal level or power for a specified active period. This approach makes it possible to reliably distinguish interference signals, which may exceed the active threshold but last only for a very short time, from useful signals to be delayed.

[0014] According to the above-described embodiment, it is of course possible not only to detect the start of the delay step, but also to identify whether the delay step is still ongoing, i.e. to identify not only the start of the delay step but also its existence.

[0015] Correspondingly, the end of the delay step or the absence of a delay step can also be identified. In a preferred embodiment of the inspection device, the end of the delay step and thus the absence of a continuous processing of the received sensor signal or of a received sensor signal derived from the received sensor signal is detected by the signal processing unit determining a signal level or a signal output of the received sensor signal or of a received sensor signal derived from the received signal and deducing the absence of a processing of the received sensor signal or of a received sensor signal derived from the received sensor signal if the determined signal level or the determined signal output is below a specified passive threshold for the signal level or signal output.

[0016] The active and passive thresholds can be chosen to be the same, in an advantageous embodiment the active threshold is chosen to be greater than the passive threshold in order to obtain some hysteresis effect.

[0017] Corresponding to the active period, a passive period can also be defined for identifying the completion of the delay step or the absence of a delay step, i.e. the signal processing unit then detects the end of the delay step and thus the completion of the continuous processing of the received sensor signal or of the received sensor signal derived therefrom when the determined signal level or determined signal output remains below a specified passive threshold for the signal level or output for the specified passive period.

[0018] In a further preferred embodiment of the test device, the active and / or passive periods are selected to be longer than the pauses between successive sensor signals of a radar frame, in particular a bundled sequence of bundled sensor signals. By selecting the detection period accordingly, it can be arranged that the switchover to the new specified value of the time delay is only performed when the transmission sequence for successive sensor signals of a radar frame is completely finished, i.e. the switchover to the new value of the specified time delay is only performed at a large transmission pause of the radar frame. This is meaningful if the distance sensor to be tested evaluates the detected data of the radar frame as a whole, in which case, on the one hand, all the received and mixed sensor signals themselves are evaluated (distance information) and on the other hand, a phase evaluation is performed with respect to the totality of the received and mixed sensor signals (velocity information).

[0019] Furthermore, a computer program is claimed, which, when executed by a signal processing unit of an inspection device for testing a distance sensor operating with electromagnetic waves in the form of at least one time-coherent and time-limited sensor signal, causes the signal processing unit and thus the inspection device to carry out the above-mentioned method.

[0020] In particular, there are several means for developing and constructing the inventive inspection device and the inventive method as defined in the independent claims, which are shown in conjunction with the illustrations in the following drawings: [Brief description of the drawings]

[0021] [Figure 1] 1 shows a schematic diagram of a known inspection device and a known method for testing a distance sensor operating with electromagnetic waves; [Diagram 2] FIG. 1 illustrates a time-coherent and time-limited sensor signal in the form of a chirp. [Diagram 3] FIG. 1 illustrates a consistent chirp sequence (frame). [Figure 4] FIG. 2 illustrates a received time-coherent and time-limited sensor signal and a time-delayed signal according to a specified time delay. [Diagram 5] FIG. 2 is a distance-velocity diagram showing a typical error-free measurement result after evaluation by a distance sensor. [Figure 6] FIG. 2 is a distance-velocity diagram showing velocity including apparent error determined by a distance sensor. [Figure 7] FIG. 1 illustrates a received time-coherent and time-limited sensor signal and a simulated time-delayed signal in response to a specified time delay, the latter simulated time-delayed signal having a specified new time delay modified in a duration delay step and taken into account with respect to the time delay, with a resulting phase jump. [Figure 8] 3A and 3B show schematic diagrams of the evaluation of a simulated reflected signal without a phase jump and with a phase jump in a range sensor; [Figure 9]FIG. 13 is a schematic diagram illustrating the time delay of a received time-coherent and time-limited sensor signal with a constant specified time delay even though the specified time delay is changed during the delay step in order to avoid phase jumps in the simulated reflected signal. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Figures 1 to 9 show, in different aspects and with different levels of detail, an inspection device 1 for testing a distance sensor 2 operating using electromagnetic waves in the form of at least one time-coherent and time-limited sensor signal, and a corresponding method 10 for operating the inspection device 1.

[0023] The distance sensor 2 emits electromagnetic free space waves in the direction of the inspection device 1 and generates a simulated electromagnetic reflected signal S TX The inspection device 1 has a receiving element 3 for receiving the free space waves emitted from the distance sensor 2 and receives a simulated electromagnetic reflected signal S TX The distance sensor 2 has a radiating element 4 for radiating a received signal S. The distance sensor 2 itself does not belong to the inspection device 1, but it is important to understand how the inspection device 1 interacts with the distance sensor 2. RX or received signal S RX A signal S' derived from RX is fed through a signal processing unit 5, which can specify a time delay within a certain range. Thus, the input signal of the time delay circuit 5 is a time delayed signal S delay The time-delayed signal S delay or the time-delayed signal S delay A signal S' derived from delay is then the simulated reflected signal S TX is radiated through the radiating element 4 as

[0024] FIG. 1 shows the time delay t delay,sollis shown to be supplied as information to the signal processing unit 5. In the case of the inspection device 1 shown here, the technical realization of how exactly this information is supplied to the signal processing unit 5 is not important. In general, the specified value for the time delay to be set comes from an environment simulator, which simulates the scene to be simulated with environmental objects and prepares the corresponding position information, velocity information and / or acceleration information of the environmental objects. For example, if it is known that the distance from the distance sensor to be tested to the object to be simulated is 30 m, then the corresponding time delay is calculated taking into account the speed of light as the signal propagation time of electromagnetic waves, and the time delay t delay,soll is specified as

[0025] FIG. 2 shows a received signal S RX A time-coherent and time-limited sensor signal is shown as . It is assumed here that the distance sensor 2 to be tested emits a signal of this type. As a special embodiment of such a time-coherent and time-limited sensor signal, a chirp signal (chirp for short) is shown here, which is a frequency-modulated signal. In this case, the frequency of the sinusoidal vibration increases over time, by definition. In the testing device 1, this chirp is then modulated by the received sensor signal S RX and also proceeds continuously and thus without phase jumps. A signal has a limited extent in time, i.e. it is a time-limited wave packet.

[0026] FIG. 3 shows a sequence of chirps which follow one another in a time-defined manner, i.e. are each separated from one another by short transmission pauses which are followed by long transmission pauses which, in the case of distance sensors 2 known in the prior art, are generally used for signal processing.

[0027] In the distance sensor 2, typically all chirps received as reflected signals, i.e. also each individual chirp of a chirp frame, are evaluated for distance measurements. By evaluating the mutual phase positions of several successive chirps in time, the radial velocity information is calculated. The basic functional scheme of the inspection device 1 and the method 10 is shown in FIG. 4. The inspection device 1 converts a time-coherent and time-limited sensor signal into a received signal S RX and this received signal S RX is shown here as a sine wave for simplicity. delay,soll If is specified, the received sensor signal S RX However, the signal processing unit 5 precisely determines this time delay value t delay,soll The time delay is t delay,soll The value specified for corresponds to the propagation time of the simulated reflected signal at the object distance to be simulated.

[0028] In Fig. 5, a distance-velocity diagram is shown, which shows the evaluation of a measurement sequence based on the evaluation of chirp frames in the distance sensor 2. It can be seen that an object is identified at a distance R with only small fluctuations and that this object has a relative radial velocity component v that is also substantially little fluctuated. This result is reasonable. If we assume, for example, that one complete chirp sequence of one frame is sent out in a few tens of milliseconds, i.e. that the measurements are also received within these few tens of milliseconds, then environmental objects known from everyday life have a location that changes only slightly and an almost constant speed, even if they move, because the location and speed do not change substantially in a short measurement period, for example in a road traffic scenario.

[0029] In Fig. 6 a further distance-velocity diagram is shown, which illustrates the evaluation of the chirp sequence by the distance sensor 2, obtained by evaluating the reflected signal simulated by the inspection device 1. It can be seen that the object is identified at an approximately constant distance, but the velocity information scatters over a very wide range. The velocity values ​​determined by the distance sensor 2 scatter, even though in this case the inspection device 1 is operating at a constant velocity v to be simulated. The question thus arises: how does this apparent erroneous evaluation arise and how can such an apparent erroneous evaluation be avoided?

[0030] The received time-consistent and time-limited sensor signal S RX During delay step 6, delay,soll is changed, and this changed specified time delay t delay,soll,neu It has been found that such an error occurs when is used as the basis for the time delay to be implemented in delay step 6.

[0031] The impact of the described approach is shown in Figure 7. The top diagram shows a received time-coherent and time-limited sensor signal S RX is again shown in the form of a sinusoidal packet. The diagram below shows the time-delayed signal S delay , i.e., the simulated reflected signal is shown. At the start of delay step 6, a specified time delay t delay,soll If there is a specified time delay t delay,soll However, in delay step 6, the actuation time delay t delay,work While the time delay is still in progress, i.e. while delay step 6 has not yet ended, a new value t delay,soll,neu is specified, and the activation time delay t delay,work It can also be used directly as the actuation time delay t delay,workThe term makes it clear that the delay values ​​are not just passively present, but are used as a basis for calculating or identifying a time delayed signal. This switching often results in a calculated time delayed signal S delay 7, a discontinuity occurs, which can also be seen in the lower diagram of Fig. 7. It has been found that this discontinuity, i.e. a jump in the phase position, is the cause of an apparently erroneous evaluation of the distance sensor 2 to be tested, which was tested by means of a testing device 1 known from the prior art. In fact, this means that the evaluation of the distance sensor 2 to be tested is not erroneous, but rather that there is a problem in the generation of the simulated reflected signal.

[0032] FIG. 8 is used to explain the problem of evaluating a simulated reflected signal with discontinuities in the distance sensor 2. Three mixed signals S M1 ,S M2 ,S M3 are shown, and the three mixed signals S M1 ,S M2 ,S M3 are based on a mixture of the transmitted chirp and a simulated reflected chirp generated by the inspection device 1 and re-received by the distance sensor 2. M1 ,S M2 ,S M3 are harmonic oscillations with a substantially fixed frequency. Each chirp or each mixed signal S M1 ,S M2 ,S M3 The time extension of S is shown extending from left to right along a first time axis. M1 ,S M2 ,S M3 are shown next to each other in time along a second time axis. M1 ,SM2 ,S M3 are subjected to frequency analysis, whereby each mixed signal S M1 ,S M2 ,S M3 Distance information is obtained from multiple different sequential mixed signals S M1 ,S M2 ,S M3 It can be seen that the first two mixed signals S M1 ,S M2 is a continuous oscillatory transition based on the mixing of two chirp signals that are both undisturbed and continuous. The third mixed signal S M3 In the case of FIG. 7, the simulated reflected signal generated by the inspection device 1 has a phase jump as explained with reference to FIG. 7 because the time-coherent and time-limited sensor signal S RX During delay step 6, two different designated time delays t delay,soll and t delay,soll,neu However, the activation time delay t delay,work The phase jump in the generated simulated reflected signal, as can be seen in FIG. 7, naturally occurs in the mixed signal S M3 This results in different phase values ​​φ in the evaluation and different corresponding velocity values ​​resulting from these phase values, which explains the problems identified when evaluating the corresponding signals in the distance sensor 2.

[0033] The problem pointed out is solved by the illustrated inspection device 1 and the illustrated method 10 as shown in detail in FIG. 9, in which a signal processing unit 5 processes the received time-consistent and time-limited sensor signal S RX or the received sensor signal S RX The received time-coherent and time-limited sensor signal S' derived from RXHowever, at the start of the delay step 6, and therefore at the time-limited received sensor signal S RX The time delay t specified at the start of processing delay,soll Even if during the delay step 6, the received sensor signal S RX or the received sensor signal S RX The received sensor signal S' derived from RX During the continuous processing of delay,soll The constant activation time delay t delay,work The fully processed and time delayed sensor signal S delay 9 shows the newly specified time delay t delay,soll,neu But the old specified time delay t delay,soll It is shown that the newly specified time delay t is blocked from being used as a new specified value for the signal delay until the end of the delay step 6 based on t delay,soll,neu However, the activation time delay t delay,work Used as.

[0034] The inspection device 1 shown in the drawings and the illustrated method 10 include, in a delay step 6, delaying the received sensor signal S RX or the received sensor signal S RX The received sensor signal S' derived from RX The fact that the received signal S is being continuously processed is detected by the signal processing unit 5 RX or received signal S RX The received signal S' derived from RX and determining a signal level A or a signal output P of the received sensor signal S when the determined signal level A or the determined signal output P is greater than a specified active threshold ASW for the signal level or signal output. RX or the received sensor signal S RXThe received sensor signal S' derived from RX is still in persistent processing ((P(S RX )vA(S RX ))>ASW).

[0035] The inspection device 1 shown in the drawings and the illustrated method 10 are characterized in that the signal processing unit 5 determines whether or not to start the delay step 6 and thus the received sensor signal S if the determined signal level A or the determined signal power P is above a specified active threshold ASW for the signal level or power for a specified active period. RX or the received sensor signal S RX The received sensor signal S' derived from RX This is done by detecting the start of a persistent process of, which is not shown in detail here.

[0036] The inspection device 1 shown in the drawing and the illustrated method 10 are adapted to detect the end of the delay step 6 and thus the received sensor signal S RX or the received sensor signal S RX The received sensor signal S' derived from RX The lack of a sustained processing of the received signal S is detected by the signal processing unit 5 RX or received signal S RX The received signal S' derived from RX and determining a signal level A or a signal output P of the received sensor signal S if the determined signal level A or the determined signal output P is below a specified passive threshold value PSW for the signal level or signal output. RX or the received sensor signal S RX The received sensor signal S' derived from RX They are furthermore common in that they are detected by presuming the absence of a process.

[0037] The inspection device 1 shown in the drawings and the illustrated method 10 are such that when a specified signal level A or a specified signal output P falls below a specified passive threshold PSW with respect to the signal level or signal output over a specified passive period t p the signal processing unit 5 is further configured to detect the completion of the continuous processing of the received sensor signal S RX or the received sensor signal S RX derived from the received sensor signal S’ RX from the received sensor signal S’((P(S RX )vA(S RX )) < PSW). In this case, the passive period t p has the length of the specified time delay t delay,work which was used as the operating time delay t delay,soll during the delay step 6. This is meaningful because the processed simulated time-delayed signal will in any case be present in the inspection device 1 for a longer time by the value of the time delay than the received signal is received.

[0038] In the illustrated embodiment of the inspection device 1 and the method 10, the passive period t p is selected to be longer than the pause between successive sensor signals of one combined sequence consisting of a plurality of sensor signals of one radar frame, i.e., one combined sequence consisting of a plurality of combined sensor signals. Thereby, it is achieved that it is possible to switch to a newly specified time delay t delay,work as the effective operating time delay t delay,soll only when sensor signals of a completely new radar frame are received.

Explanation of Reference Numerals

[0039] 1 Inspection device 2 Distance sensor 3 Receiving element 4 Transmitting element 5 Signal processing unit 6 Delay step 10 Method S RX Received signal S' RX Received signal S RX The received signal derived from S TX Output Signal t delay,soll Configurable Time Delay S delay Time Delayed Signal S' delay A time-delayed signal derived from a time-delayed signal t delay,soll,neu The new specified time delay t delay,work Fixed activation time delay t delay,soll Configurable Time Delay S M1 ,S M2 ,S M3 mixed signal φ Phase offset R Distance v speed A. Signal Level P signal output ASW Active Threshold PSW Passive Threshold t p Passive Period

Claims

1. An inspection device (1) for testing a distance sensor (2) that operates using electromagnetic waves in the form of at least one sensor signal that is temporally consistent and temporally limited, The inspection device (1) detects a received signal (S ＲＸ a receiving element (3) for receiving an electromagnetic free space wave as an electromagnetic output signal (S ＴＸ and a radiating element (4) for radiating a beam of light, During the simulation operation, the received signal (S ＲＸ ), or the received signal (S ＲＸ )-derived received signal (S' ＲＸ ) is supplied via the signal processing unit (5) with a specifiable time delay (t ｄｅｌａｙ，ｓｏｌｌ ), whereby, as a simulated reflected signal, it is time-delayed to become a time-delayed signal (S ｄｅｌａｙ ). The time-delayed signal (S ｄｅｌａｙ ), or the time-delayed signal (S ｄｅｌａｙ )-derived time-delayed signal (S' ｄｅｌａｙ ), is radiated as an output signal (S ＴＸ ) through the radiation element (4) in the inspection device (1). The received temporally coherent and temporally limited sensor signal (S ＲＸ ), or the received temporally coherent and temporally limited sensor signal (S’ ＲＸ ), derived from the received sensor signal (S ＲＸ ), in the delay step (6), at the start of the delay step (6), and thus at the start of the processing of the received temporally limited sensor signal (S ＲＸ ), a time delay (t ｄｅｌａｙ，ｓｏｌｌ ), even if during the delay step (6), and thus during the continuous processing of the received sensor signal (S ＲＸ ), or the received sensor signal (S’ ＲＸ ), derived from the received sensor signal (S ＲＸ ), the specified time delay (t ｄｅｌａｙ，ｓｏｌｌ ), is changed, is used as a constant operating time delay (t ｄｅｌａｙ，ｗｏｒｋ ), and is completely processed to generate a time-delayed sensor signal (S ｄｅｌａｙ ). the inspection device (1).

2. In the delay step (6), it is detected by the following that the received sensor signal (S ＲＸ ), or the received sensor signal (S’ ＲＸ ) derived from the received sensor signal (S ＲＸ ) is in continuous processing, that is, the signal processing unit (5) determines the signal level (A) or signal output (P) of the received signal (S ＲＸ ), or the received signal (S’ ＲＸ ) derived from the received signal (S ＲＸ ), and if the determined signal level (A) or the determined signal output (P) exceeds the active threshold (ASW) specified for the signal level or the signal output, it is detected by presuming that the received sensor signal (S ＲＸ ), or the received sensor signal (S’ ＲＸ ) derived from the received sensor signal (S ＲＸ ) is still in continuous processing. The inspection device (1) according to Claim 1.

3. If the specified signal level (A) or the specified signal output (P) exceeds the specified active threshold (ASW) for the signal level or the signal output over a specified active period, the signal processing unit (5) starts the delay step (6) and thus starts the continuous processing of the received sensor signal (S ＲＸ ), or the received sensor signal (S ＲＸ ) derived from the received sensor signal (S ＲＸ ). The inspection device (1) according to Claim 2.

4. the end of the delay step (6) and thus the lack of continuous processing of the received sensor signal (S ＲＸ ) or of the received sensor signal (S ＲＸ ) derived from the received sensor signal (S') ＲＸ ) is detected by the fact that the signal processing unit (5) determines the signal level (A) or the signal output (P) of the received signal (S ＲＸ ) or of the received signal (S') ＲＸ ) derived from the received signal (S) and, if the determined signal level (A) or the determined signal output (P) is below a passive threshold value (PSW) specified for the signal level or the signal output, the non-existence of the processing of the received sensor signal (S ＲＸ ) or of the received sensor signal (S') ＲＸ ) derived from the received sensor signal (S) is detected by presuming it, ＲＸ ) or of the received sensor signal (S') ＲＸ ) derived from the received sensor signal (S The inspection device (1) according to Claim 1.

5. If the specified signal level (A) or the specified signal output (P) falls below the passive threshold (PSW) specified for the signal level or the signal output over a specified passive period (t ｐ ), then the signal processing unit (5) detects the end of the delay step (6) and thus the completion of the continuous processing of the received sensor signal (S ＲＸ ) or the received sensor signal (S ＲＸ ) derived from the received sensor signal (S ＲＸ ). The inspection device (1) according to Claim 4.

6. The active period and / or the passive period (t ｐ ) is selected to be longer than the pauses between successive sensor signals of one combined sequence consisting of a plurality of sensor signals of one radar frame, in particular of one combined sequence of a plurality of combined sensor signals. The inspection device (1) according to Claim 3 or 5.

7. A method (10) implemented by a computer for operating an inspection device (1) for testing a distance sensor (2) that operates using electromagnetic waves in the form of at least one sensor signal that is temporally consistent and temporally limited, wherein the inspection device (1) comprises a received signal (S ＲＸ ), a receiving element (3) for receiving electromagnetic free space waves as), a transmitting element (4) for transmitting an electromagnetic output signal (S ＴＸ ), and a signal processing unit (5). During the simulation operation, the received signal (S ＲＸ ), or the received signal (S ＲＸ )-derived received signal (S' ＲＸ ) is supplied through the signal processing unit (5) with a specifiable time delay (t ｄｅｌａｙ，ｓｏｌｌ ), whereby it is time-delayed to become a time-delayed signal (S ｄｅｌａｙ ) as the simulated reflected signal. The time-delayed signal (S ｄｅｌａｙ ), or the time-delayed signal (S ｄｅｌａｙ )-derived time-delayed signal (S' ｄｅｌａｙ ), in a method (10) of being radiated as an output signal (S ＴＸ ) via the radiating element (4). The received temporally consistent and temporally limited sensor signal (S ＲＸ ), or the received temporally consistent and temporally limited sensor signal (S’ ＲＸ ) derived from the received sensor signal (S ＲＸ ), in the delay step (6), at the start of the delay step (6), and thus at the start of the processing of the received temporally limited sensor signal, the specified time delay (t ｄｅｌａｙ，ｓｏｌｌ ), even if during the delay step (6), and thus during the continuous processing of the received sensor signal (S ＲＸ ) or the received sensor signal (S ＲＸ ) derived from the received sensor signal (S ＲＸ ), the specified time delay (t ｄｅｌａｙ，ｓｏｌｌ ) is changed, is used as a constant operating time delay (t ｄｅｌａｙ，ｗｏｒｋ ) to be completely processed, and a time-delayed sensor signal (S ｄｅｌａｙ ) is generated, characterized in that A method (10).

8. Relating to the method (10) implemented by the signal processing unit (5), having the features described in at least one sub - concept of Claims 2 to 5, the method (10) according to Claim 7.

9. A computer program comprising instructions for causing the signal processing unit (5) to implement the method (10) according to Claim 7 when executed by the signal processing unit (5) of an inspection device (1) for testing a distance sensor (2) that operates using electromagnetic waves in the form of at least one sensor signal that is temporally consistent and temporally limited.

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