Verification device for testing distance sensor operating with electromagnetic waves and frequency divider device for such verification device

Abstract

The invention relates to a testing device (1) for testing a distance sensor (2) operating with electromagnetic waves, comprising: a receiving element (3) for receiving free-space electromagnetic waves as a reception signal (SRX) comprising a reception frequency (fRX) and a signal bandwidth (B); a transmitting element (4) for transmitting an electromagnetic output signal (STX), the reception signal (SRX) or a reception signal (S 'RX) derived from the reception signal (SRX) being converted into a scanned signal by means of an analog / digital converter (5) in an analog mode, the scanned signal being delayed in time by means of a signal processing unit (6) into a time-delayed scanned signal, the time-delayed scanned signal is converted into an analog reflected signal (Ssim) by means of a digital / analog converter (7), the analog reflected signal (Ssim) or an analog reflected signal (S 'sim) derived from the analog reflected signal (Ssim) being emitted as an output signal (STX) by a transmitting element (4). Simplified signal processing is achieved by dividing the received signal (SRX) into a first partial received signal (S1) and a second partial received signal (S2) by means of a signal distributor (10), dividing the first partial received signal (S1) by means of a frequency divider, obtaining amplitude information (A) of the received signal from the second partial received signal (S2), and generating a frequency-divided received signal with amplitude information (A) from the two partial received signals by means of a modulator.

Description

Technical Field

[0001] The present invention relates to an inspection device for testing a distance sensor operating with electromagnetic waves, the inspection device comprising: a receiving element for receiving free-space electromagnetic waves as a received signal comprising a received frequency and a signal bandwidth; a transmitting element for transmitting an electromagnetic output signal, wherein, in simulation operation, the received signal or a received signal derived from the received signal is converted into a scanned signal by means of an analog / digital converter, the scanned signal is time-delayed by a signal processing unit into a time-delayed scanned signal, and the time-delayed scanned signal is converted into an analog reflected signal by means of a digital / analog converter, wherein the analog reflected signal or an analog reflected signal derived from the analog reflected signal is transmitted as an output signal through the transmitting element. Furthermore, the present invention also relates to a frequency divider device for the aforementioned inspection device. Background Art

[0002] Inspection devices of the above type for testing distance sensors are known from different fields of technology, for example from the field of development and testing of control devices, especially in the automotive field; for this purpose, for example, reference is made to WO 2020 / 165191 A1. Another application field is the off-line test bench, i.e., an institution for product inspection at the end of a production line, and thus in the present case for inspecting distance sensors (EP 4109125 A1).

[0003] Here, the testing of distance sensors is concerned, which operate with electromagnetic waves, and in the automotive field, radar sensors are mainly used. In principle, however, it is also possible to test distance sensors that operate with electromagnetic waves in other frequency ranges, such as in the visible light range, or distance sensors that operate with an electromagnetic emission source that emits electromagnetic waves with a long coherence length, such as in laser applications.

[0004] With this type of inspection device, it is possible to simulate reflection objects at practically any distance from the distance sensor to be tested. Distance sensors of the type considered here generally operate in such a way that the electromagnetic waves emitted by them are reflected by reflection objects in the emission range of the distance sensor, the distance sensor receives the reflected electromagnetic waves and determines the distance to the object from the travel time of the electromagnetic waves. The determination of the signal travel time can be achieved directly (time-of-flight measurement), but this is often achieved indirectly by means of sophisticated signal analysis. In the first case, very short sensor signals are often used, i.e., pulsed operation, while in the latter case, time-dilated transmitted signals are mostly used and the desired distance information is obtained from the frequency of the mixed signal composed of the transmitted signal and the received reflected signal. An example of a time-dilated transmitted signal is a frequency-modulated continuous-wave signal.

[0005] In order to test the distance sensor, a test device is positioned in its transmission range, which receives the free-space wave emitted by the distance sensor and delays the received signal by means of its signal processing unit according to a predetermined time delay and then transmits the time-delayed signal via its transmitting element in the direction of the distance sensor to be tested, thereby creating in the distance sensor the impression of a reflecting object that is moving away according to the set time delay.

[0006] The adjustability of the time delay is a minimum requirement for the test device, since it allows the basic characteristics of the distance of the reflecting object to be simulated. Advanced test devices can also simulate radial motion components relative to the distance sensor. Due to the Doppler effect, the reflected signal is shifted in frequency relative to the frequency of the transmission signal emitted by the distance sensor. Modern test devices are capable of performing a corresponding frequency shift of the simulated reflected signal relative to the frequency of the received signal in order to depict a predetermined radial motion component in the simulated reflected signal. In even more advanced technologies, complex Doppler characteristics with multiple motion components can also be simulated.

[0007] On the input side, the received signal and the received signal derived from the received signal are referred to, while on the output side, the simulated reflection signal and the simulated reflection signal derived from the simulated reflection signal are referred to. The background to this is simply that the originally received received signal may also pass through a preceding signal processing on the path for digital signal processing by the signal processing unit, so that strictly it is necessary to distinguish between the received signal itself and the possibly intermediately processed received signal, which is then no longer the original received signal, but a received signal derived from the received signal. Thus, the fact lies precisely in the following signal path, which is connected after the digital signal processing. Moreover, it is possible here that the simulated reflection signal also undergoes an intermediate signal processing on the path to the transmitting element, so that strictly therefore not the simulated reflection signal is emitted as the output signal, but just the simulated reflection signal derived from the simulated reflection signal.

[0008] The requirements on the test device and thus on the signal processing unit are very high in terms of hardware. The distance sensor often works in the range of 80 GHz with a bandwidth of several GHz. A specific example of a common application of the test device for testing the distance sensor today is a receiving frequency (intermediate frequency) of 79 GHz with a bandwidth of 4 GHz, so that the received signal to be processed is in the range of 77 to 81 GHz. It is undoubtedly possible that the detection of the received signal, the processing of the received signal (scanning by analog / digital conversion, time delay, frequency shift, application of complex Doppler characteristics, digital / analog conversion) are extremely demanding, because the processing time is in the range of nanoseconds to microseconds.

[0009] In order to simulate reflecting objects with different reflection properties, such as different sizes of the object, different surface material properties or different spatial orientations of the reflecting surface, it is also important that, in any case for the testing of such a distance sensor (which also analyzes the amplitude of the reflected signal), the simulated reflected signal has a signal amplitude which is matched to the size of the reflecting object to be simulated by its size. In short, the simulated reflected signal should have an amplitude which corresponds to the radar cross-section of the object at a determined distance, but the signal amplitude received therefor must also be known. Summary of the Invention

[0010] The object of the present invention is to design and improve the described testing device in such a way that the required signal processing is simplified.

[0011] The above-derived object is solved in the testing device described at the beginning in such a way that the received signal is divided into a first partial received signal and a second partial received signal by means of a signal distributor, wherein at least the second partial received signal has amplitude information of the received signal. In the case of the application of a known signal distributor, usually both partial received signals have amplitude information of the received signal. When it is said that the second partial received signal has amplitude information of the received signal, then the second partial received signal does not have to have the amplitude of the received signal, but the amplitude of the second partial received signal is in any case in a determined ratio to the amplitude of the received signal, so that information about the amplitude of the received signal can be obtained by analyzing the amplitude of the second partial received signal.

[0012] The first partial received signal is converted by means of a frequency divider into a frequency-divided received signal which no longer has amplitude information of the received signal. The reason why the frequency-divided received signal no longer has amplitude information of the received signal (even if the first partial received signal still has amplitude information) is that most frequency dividers work digitally and usually produce a rectangular signal of the corresponding frequency from a sinusoidal oscillation, but its amplitude only oscillates between a minimum and a maximum.

[0013] The application of the frequency divider causes two effects. On the one hand, the received frequency is reduced by division according to the division factor of the frequency divider. But on the other hand, the bandwidth of the received signal is also reduced by the division factor of the frequency divider. The two effects result in: subsequent signal processing (analog / digital conversion, digital signal processing by a signal processing unit and digital / analog conversion) is greatly simplified and also more cost-effective in implementation, because slower components can be used.

[0014] Furthermore, the amplitude information of the received signal is obtained from the received signal of the second part by means of an amplitude detector. In the received signal of the second part, therefore, it is not the frequency of the received signal that is of interest, but merely its amplitude, which mostly changes more slowly than the oscillation of the received signal. Then basically envelope detection is carried out.

[0015] Now, using a modulator, a frequency-divided received signal with the amplitude information of the received signal is generated in such a way that the amplitude information obtained from the received signal of the second part is modulated onto a frequency-divided received signal without amplitude information. The frequency-divided received signal with the modulated amplitude information is then a received signal derived from the said received signal, which is subsequently processed further digitally.

[0016] By dividing the received signal into a first part received signal and a second part received signal and by the different processing of the respective part received signals in separate signal paths, once with respect to frequency and once with respect to amplitude, a very simple signal processing can be achieved, i.e., without loss of amplitude information, which would be inevitable if only one signal path with a frequency divider were used. Thereby, it is also possible to very simply match the analog reflected signal to the predetermined radar cross-section of a fictitious reflecting object in the case of a predetermined and to be simulated distance, which is not possible without knowledge of the amplitude of the received signal.

[0017] In the test device, it is furthermore provided that the analog reflected signal is converted by means of a frequency multiplier into a signal derived from the said analog reflected signal, i.e., the signal which is reduced in terms of frequency on the input side by means of a frequency divider is now increased again in terms of frequency on the output side.

[0018] According to a preferred design of the test device, the signal distributor is implemented as a resistive power distributor. This electronically passive solution can be simply implemented and is very reliable. In principle, it is also possible to use an active signal distributor or a signal distributor based on other principles.

[0019] Another advantageous design of the test device is characterized in that the frequency divider is implemented by digital technology, in particular based on bistable flip-flops. This solution is also reliable and simple and is also available as an integrated circuit. By cascading the flip-flops, in particular, a frequency divider with a division factor equal to the reciprocal of a power of two can be simply implemented.

[0020] A preferred design of the test device is characterized in that an amplitude detector including a rectifier and a subsequent low-pass filter is implemented, in particular an amplitude detector including a diode as the rectifier. This solution is also characterized in that this solution is implemented passively, simply and reliably in electronics technology.

[0021] In an advantageous further development of the test device, the division factor of the frequency divider is selected such that the minimum frequency of the divided received signal is equal to or greater than the signal bandwidth of the received signal multiplied by half of the division factor. If the division factor is 1 / x and the bandwidth of the received signal is B, then the divided received signal has a bandwidth of B / x. If the minimum frequency of the divided received signal is f min , then the given sizing rule is according to the formula f min > B / (2x). This sizing takes into account that the rectangular signal generated by the frequency allocation has higher harmonics including odd multiples of the fundamental frequency. In the implementation of the frequency divider, the first harmonic of the minimum frequency of the divided received signal is in a higher frequency range compared to the maximum frequency of the divided received signal and thus outside the divided bandwidth of the divided received signal.

[0022] In another advantageous design of the test device, it is provided that the low-pass filter filters the divided received signal having amplitude information, so as to obtain the fundamental oscillation of the harmonics of the divided received signal as the derived received signal. By filtering, a harmonic signal is generated from the rectangular signal, or the harmonic of interest of the fundamental frequency is extracted from a signal having multiple energy components in the harmonic oscillation. The low-pass filter can also be directly arranged behind the frequency divider, thus resulting in a harmonic signal without amplitude information and this harmonic signal can then be provided with amplitude information by modulation.

[0023] In an advantageous further development of the test device, the cut-off frequency of the low-pass filter lies between twice and three times the minimum frequency of the divided received signal. This is particularly meaningful if the division factor of the frequency divider is selected as described above.

[0024] In an advantageous design of the test device and the frequency divider device, a delay element is arranged in the signal path between the signal distributor via the frequency divider to the modulator and / or between the signal distributor via the amplitude detector to the modulator, wherein the delay element has such a delay time that the divided received signal and the amplitude information are combined in a timely appropriate manner. Thereby, the different signal propagation times in the respective signal paths starting from the signal distributor are compensated.

[0025] In another advantageous design of the test device, the multiplication factor of the frequency multiplier corresponds to the reciprocal of the division factor of the frequency divider, thereby raising the analog reflected signal again to the reception frequency and also expanding the signal bandwidth of the analog reflected signal to the signal bandwidth of the received signal.

[0026] Preferably, the frequency multiplier is implemented using a semiconductor component with non-linear transmission performance, thereby automatically generating higher harmonics. Suitable as a simple component is a diode or a transistor. Then preferably a band-pass filter is arranged behind the frequency multiplier in order to filter or pass through the harmonic oscillations in the desired frequency range.

[0027] In another advantageous design of the testing device, the received signal is frequency-shifted towards lower frequencies using a receiving converter, and the signal derived from the analog reflected signal (i.e., after the frequency multiplier) is frequency-shifted towards higher frequencies using an output converter, wherein the frequency shift is in particular numerically the same on the input and output sides. The use of the receiving converter and the output converter does not affect the signal bandwidth, but reduces or increases the frequency of the signal band. The frequency-shifted received signal is then the input signal of the signal distributor previously referred to as the received signal.

[0028] The task described at the beginning is also solved using a frequency divider device for a testing device according to the invention. The frequency divider device is characterized in that the received signal is divided into a first partial received signal and a second partial received signal using a signal distributor, wherein at least the second partial received signal has the amplitude information of the received signal; the first partial received signal is converted into a frequency-divided received signal that no longer has the amplitude information of the received signal using a frequency divider; the amplitude information of the received signal is obtained from the second partial received signal using an amplitude detector; a frequency-divided received signal having the amplitude information of the received signal is generated using a modulator, in such a way that the amplitude information obtained from the second partial received signal is modulated onto the frequency-divided received signal without amplitude information and thus a derived received signal is generated from the received signal. The frequency divider device is designed with respect to its components as described previously in connection with the testing device. Description of the Drawings

[0029] In detail, there are now various possibilities to design and further expand the testing device according to the invention and the frequency divider device according to the invention. For this purpose, reference is made on the one hand to the claims following the independent claims and on the other hand to the following description of the embodiments in conjunction with the drawings. In the figures:

[0030] Figure 1 Schematically shows a testing device known from the prior art for testing a distance sensor operating with electromagnetic waves;

[0031] Figure 2 Schematically shows the amplitude spectra of a received signal and a received signal derived therefrom, also known from the prior art;

[0032] Figure 3 Shows a frequency divider device implemented in the receiving path of a testing device according to the invention;

[0033] Figure 4 Schematically shows a frequency multiplier in the output path of an inspection device according to the present invention;

[0034] Figure 5 Schematically shows another embodiment of a frequency divider device of an inspection device;

[0035] Figure 6 Schematically shows another embodiment of a frequency divider device in an inspection device;

[0036] Figure 7 Schematically shows an inspection device having a frequency converter with an input side and an output side; and

[0037] Figure 8 Schematically shows the amplitude spectra of different signals in the case of a frequency divider device in an application inspection device. Detailed Description

[0038] Figure 1 Shows an inspection device 1 known from the prior art for testing a distance sensor 2 operating with electromagnetic waves. The distance sensor 2 is, for example, a radar distance sensor as used in the automotive field. The distance sensor 2 emits free-space waves - which are reflected on a reflecting object - and receives the reflected signal. From the time delay, frequency shift, and optionally the signal intensity of the reflected signal, the distance sensor can infer the distance to the reflecting object, the radial velocity component of the reflecting object, and optionally the size, reflection characteristics, etc. of the reflecting object; this depends on the design of the distance sensor 2. The inspection device 1 disguises an actual reflecting object for the distance sensor 2 to be tested.

[0039] The inspection device 1 has a receiving element 3 for receiving the free-space electromagnetic wave emitted by the distance sensor 2 as a received signal S RX . The received signal S RX has a received frequency f RX and a signal bandwidth B. In addition, the inspection device 1 has a transmitting element 4 for transmitting an electromagnetic output signal S TX .

[0040] In the analog operation, the received signal S RX or a received signal S' derived from the received signal S RX is converted into a sampled signal by means of an analog / digital converter 5, the sampled signal is time-delayed by a signal processing unit 6 to a time-delayed sampled signal, and the time-delayed sampled signal is converted into an analog reflected signal S RX by means of a digital / analog converter 7. Subsequently, the analog reflected signal S sim or a reflected signal S' derived from the analog reflected signal S sim or simThe derived simulated reflected signal S' sim is used as the output signal S TX and is transmitted by the transmitting element 4.

[0041] The signal processing unit 6 implements the necessary measures to provide all the main signal characteristics to the simulated reflected signal, namely the desired signal delay, the desired frequency shift (or signal components with multiple different frequency shifts), and, if necessary, also the desired amplitude of the simulated reflected signal S sim .

[0042] In addition, as indicated in Figure 1 , there can be a signal processing 8a in front of the input side and also a signal processing 8b behind the output side for the signal processing of the signal processing unit 6. For example, it is known to mix down the received signal S RX to a lower frequency range using an input mixer, where the bandwidth of the signal is retained. Thus, from the received signal S RX a received signal S' RX derived from the received signal S RX is generated. This situation is shown in terms of the amplitude spectrum in Figure 2 . The received signal S RX has a bandwidth B of 4 GHz at a reception frequency f RX of 79 GHz. The signal bandwidth B thus extends from 77 GHz to 81 GHz. By applying a mixer, which is part of the signal processing 8a in front of the input side, the received signal S RX is mixed down to an intermediate frequency of 4 GHz in the case of applying a local oscillator frequency of 75 GHz, where the signal bandwidth B is retained. Thus, in this example, a received signal S' RX derived from the received signal S RX is generated.

[0043] What is not shown explicitly is that in the signal processing 8B behind the output side, a corresponding mixer is applied, whereby the low-frequency simulated reflected signal S sim is mixed up again into the range of the reception frequency f RX and is then transmitted as the derived simulated reflected signal S' sim . Since the bandwidth B of the received signal S RX remains unchanged, the requirements related to the signal bandwidth B for the scanning of the signal are retained and remain high without change.

[0044] In Figures 3 to 8 , different aspects of the test device 1 for testing the distance sensor 2 operating with electromagnetic waves according to the invention and the frequency divider device 9 according to the invention, which is part of the test device 1, are described.

[0045] exist Figure 3 1 shows first a frequency divider device 9, which is a component of the signal processing preceding the input side. It can be seen that the received signal S RX The signal distributor 10 is used to divide the received signal into a first received signal S1 and a second received signal S2, wherein at least the second received signal S2 has a received signal S RX In this case, the signal distributor 10 is a resistive power distributor, so that the first partial received signal S1 also has the received signal S RX The first part of the received signal S1 is converted into a signal that no longer has the amplitude information A of the received signal S by using the frequency divider 11. RX The amplitude information A of the divided received signal S 1f The divided received signal S 1f Therefore, there is no amplitude information A, since the frequency divider 11 outputs a digital output signal, ie, it still has frequency information, but no longer contains the amplitude information of the divided input signal.

[0046] The received signal S is obtained by using the amplitude detector 12 from the second received signal S2. RX Amplitude information A. In this case, the envelope of the second partial received signal S2 is detected.

[0047] Finally, the modulator 13 generates a received signal S RX The amplitude information A of the divided received signal S fA The method is to modulate the amplitude information A obtained from the second partial received signal S2 to the divided received signal S without amplitude information. 1f Thus, the received signal S is generated. RX The derived received signal S' RX The frequency divider device 9 can be used to compensate for the loss of amplitude information A in an elegant manner when using the frequency divider 11 by regaining the amplitude information A in a separate signal path and modulating the divided received signal S which no longer has the amplitude information A. 1f The use of the frequency divider 11 has the advantage that not only the received frequency f RX , that is, the received signal S RX The intermediate frequency of the frequency divider 11 is reduced by 1 / x, and the received signal S RX The signal bandwidth B is reduced by the same factor, so that the requirements for further signal processing are correspondingly lower.

[0048] exist Figure 4 Another aspect of the test device 1 is shown in FIG. 1 , namely the simulated reflection signal S sim The frequency multiplier 14 converts the reflected signal S into an analog signal.sim The derived signal S' sim . In this case, the multiplication factor y of the frequency multiplier 14 is equal to the reciprocal of the division factor 1 / x of the frequency divider 11. Thus, the effect of the frequency divider 11 (the reduction of the intermediate frequency and the reduction of the bandwidth) is accurately eliminated.

[0049] In the illustrated embodiment, the frequency divider 11 is implemented by digital technology, i.e., based on fast bistable flip-flops.

[0050] In the illustrated embodiment, the amplitude detector 12 including a rectifier and a subsequent low-pass filter is implemented, i.e., an amplitude detector including a diode as the rectifier (not shown separately in detail).

[0051] In Figure 5 it is shown that the low-pass filter 18 follows the frequency divider 11, and the low-pass filter only allows the fundamental oscillation of the harmonics of the divided received signal S 1f to pass through. In this way, the rectangular signal caused by frequency division can be converted into a clean sinusoidal oscillation in a simple manner.

[0052] Figure 6 An alternative implementation of the test device 1 or the frequency divider device 9 is shown, in which the low-pass filter 18 filters the divided received signal S with amplitude information fA such that only the fundamental oscillation of the harmonics of the divided received signal S fA passes through as the derived received signal S' RX .

[0053] In the two previously described embodiments according to Figure 5 and 6 , the low-pass filter 18 is designed such that the cut-off frequency is between twice and three times the minimum frequency of the divided received signals S 1f , S fA .

[0054] Common to each embodiment is that the multiplication factor y of the frequency multiplier 14 corresponds to the reciprocal of the division factor x of the frequency divider 11, whereby the frequency shift, as well as the reduction and expansion of the bandwidth, are eliminated on the input side and the output side.

[0055] Even if not shown in detail, what is common to the test device 1 in each embodiment is that the frequency multiplier 14 is implemented using diodes in order to generate higher harmonics. In order to filter the higher harmonics (in this case, the higher harmonics with multiple fundamental frequencies), a band-pass filter is provided downstream.

[0056] Figure 7 The test device 1 is shown, in which the received signal S RXFrequency shift is performed towards a lower frequency using the receiving converter 15, and the output signal of the frequency doubler 14 is shifted towards a higher frequency using the output converter 16, where the frequency shifts are numerically the same. The receiving converter 15 and the output converter 16 are mixers, and the mixers are supplied with harmonic signals having corresponding frequencies by the local oscillator 17 in order to raise and lower the corresponding frequencies of the input signals. The received signal S RX has already been frequency-shifted here before being further processed in the described manner by the frequency divider device 9. In order not to have to apply additional reference numerals, it is still referred to as the received signal S RX .

[0057] Figure 8 Shows the amplitude spectra of different signals that are caused in the case of the frequency divider device 9 of the test device 1 applied in accordance with Figure 7 . Also here, the received signal S RX has a bandwidth B of 4 GHz at an intermediate frequency of 79 GHz. The receiving converter 15 is fed a mixing frequency of 75 GHz by the local oscillator 17, resulting in a reduced received signal S with a constant 4 GHz bandwidth B in the range from 2 to 6 GHz RX . This signal is fed to the frequency divider device 9, where the frequency divider 11 used has a division factor 1 / x = 1 / 4. Thus, the bandwidth B is reduced by a factor of 4, i.e., to 1 GHz. The limited frequency is also reduced by a factor of 4 and now lies between 0.5 GHz and 1.5 GHz. In the selection of the division factor 1 / x, it is noted that the minimum frequency of the divided received signal S 1f is equal to or greater than the signal bandwidth B of the received signal multiplied by half of the division factor 1 / x, i.e., multiplied by 1 / (2x).

[0058] The bandwidth-reduced (B / x), the received signal S' RX derived from the received signal S RX can be operated more simply by subsequent digital signal processing compared to the signal with the original larger bandwidth B. Thus, it is possible to apply a small number of fast power electronic components, which enables the application of less demanding and therefore often also cheaper hardware components.

[0059] List of reference numerals

[0060] 1 Test device

[0061] 2 Spacing sensor

[0062] 3 Receiving element

[0063] 4 Transmitting element

[0064] 5 Analog / digital converter

[0065] 6 Signal processing unit

[0066] 7 Digital / analog converter

[0067] 8a Signal processing before the input side

[0068] 8b Signal processing after the output side

[0069] 9 Frequency divider device

[0070] 10 Signal distributor

[0071] 11 Frequency divider

[0072] 12 Amplitude detector

[0073] 13 Modulator

[0074] 14 Frequency multiplier

[0075] 15 Receive converter

[0076] 16 Output converter

[0077] 17 Local oscillator

[0078] 18 Low-pass filter

[0079] S RX Received signal

[0080] f RX Receive frequency

[0081] B Bandwidth of the received signal

[0082] S' RX Received signal derived from the received signal S RX Received signal derived

[0083] S TX Output signal

[0084] S sim Analog reflected signal

[0085] S' sim Derived analog reflected signal

[0086] S1, S2 First and second part received signals

[0087] A Amplitude information

[0088] S 1f Divided received signal without amplitude information

[0089] S fA Divided received signal with modulated amplitude information

[0090] Division factor of the 1 / x frequency divider

[0091] Multiplication factor of the y frequency multiplier

Claims

1. A test device (1) for testing a spacing sensor (2) operating with electromagnetic waves, the test device comprising: Receiving element (3) for receiving free-space electromagnetic waves as a received signal (S RX ) comprising a received frequency (f RX ) and a signal bandwidth (B); transmitting element (4) for transmitting an electromagnetic output signal (S TX ), wherein, in analog operation, the received signal (S RX ) or a received signal (S' RX ) derived from the received signal (S RX ) is converted into a sampled signal by means of an analog / digital converter (5), the sampled signal is time-delayed by a signal processing unit (6) to a time-delayed sampled signal, and the time-delayed sampled signal is converted into an analog reflected signal (S sim ) by means of a digital / analog converter (7), wherein the analog reflected signal (S sim ) or an analog reflected signal (S' sim ) derived from the analog reflected signal (S sim ) is transmitted as the output signal (S TX ) by means of the transmitting element (4), characterized in that the received signal (S RX ) is divided by a signal distributor (10) into a first partial received signal (S1) and a second partial received signal (S2), wherein at least the second partial received signal (S2) has the amplitude information (A) of the received signal (S RX ); the first partial received signal (S1) is converted by a frequency divider (11) into a frequency-divided received signal (S RX ) no longer having the amplitude information (A) of the received signal (S 1f ); the amplitude information (A) of the received signal (S RX ) is obtained from the second partial received signal (S2) by means of an amplitude detector (12); a frequency-divided received signal (S RX ) having the amplitude information (A) of the received signal (S fA ) is generated by a modulator (13) by modulating the amplitude information (A) obtained from the second partial received signal (S2) onto the frequency-divided received signal (S 1f ) without amplitude information and thus generating a received signal (S' RX ) derived from the received signal (S RX ); and Convert the simulated reflected signal (S sim ) using a frequency multiplier (14) into a signal (S' sim ) derived from the simulated reflected signal (S sim ).

2. The inspection device (1) according to claim 1, characterized in that, The signal distributor (10) is implemented as a resistive power distributor.

3. The inspection device (1) according to claim 1 or 2, characterized in that, The frequency divider (11) is implemented by digital technology, in particular based on bistable flip-flops.

4. The inspection device (1) according to one of claims 1 to 3, characterized in that, Implement an amplitude detector (12) including a rectifier and a subsequent low-pass filter, in particular an amplitude detector including a diode as the rectifier.

5. The inspection device (1) according to any one of claims 1 to 4, characterized in that Select the division factor (1 / x) of the frequency divider (11) such that the minimum frequency of the divided received signal (S 1f ) is equal to or greater than the signal bandwidth (B) multiplied by half of the division factor (1 / x).

6. The inspection device (1) according to any one of claims 1 to 5, characterized in that, The low-pass filter (18) filters the frequency-divided received signal (S fA ) having amplitude information, thereby obtaining the fundamental oscillation of the harmonics of the frequency-divided received signal (S fA ) as the derived received signal (S' RX ).

7. The inspection device (1) according to claim 6, characterized in that, The cut-off frequency of the low-pass filter (18) is between double and triple the smallest frequency of the frequency-divided received signals (S 1f , S fA ).

8. The inspection device (1) according to any one of claims 1 to 6, characterized in that The multiplication factor (y) of the frequency multiplier (14) corresponds to the reciprocal of the division factor (1 / x) of the frequency divider (11).

9. The inspection device (1) according to one of claims 1 to 8, characterized in that, The frequency multiplier (14) is implemented in the case of using a semiconductor component with a non-linear transmission performance for generating higher harmonics, in particular in the case of using a diode or a transistor.

10. The inspection device (1) according to one of claims 1 to 9, characterized in that, Using a reception converter (15) to frequency-shift the received signal (S RX ) towards a lower frequency, and using an output converter (16) to frequency-shift the output signal of the multiplier (14) towards a higher frequency, in particular where the frequency shifts are numerically the same.

11. A frequency divider device (9) for an inspection device (1) according to one of claims 1 to 10, characterized in that, The received signal (S RX ) is divided by a signal distributor (10) into a first-part received signal (S1) and a second-part received signal (S2), wherein at least the second-part received signal (S2) has the amplitude information (A) of the received signal (S RX ); the first-part received signal (S1) is converted by a frequency divider (11) into a frequency-divided received signal (S RX ) that no longer has the amplitude information (A) of the received signal (S 1f ); the amplitude information (A) of the received signal (S RX ) is obtained from the second-part received signal (S2) by an amplitude detector (12); a frequency-divided received signal (S RX ) having the amplitude information (A) of the received signal (S fA ) is generated by a modulator (13) in such a manner that the amplitude information (A) obtained from the second-part received signal (S2) is modulated onto the frequency-divided received signal (S 1f ) that has no amplitude information (A) and thus a derived received signal (S RX ) is generated from the received signal (S RX ).

12. The frequency divider device (9) according to claim 11, characterized in that Features of the characterizing part of at least one of claims 2 to 7.

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