Test device for testing a distance sensor that operates using electromagnetic waves, and frequency divider assembly for such a test device
Patent Information
- Application Number
- EP2023820807
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-12-13
- Filing Date
- 2023-12-04
- Publication Date
- 2025-10-22
AI Technical Summary
Current test devices for distance sensors operating with electromagnetic waves face challenges in simplifying signal processing due to high hardware requirements, particularly in handling signals in the 80 GHz range with bandwidths of a few GHz, which demands extremely fast processing times and complex signal evaluations.
The test device employs a signal divider to separate the received signal into two partial signals, where one partial signal retains amplitude information, and a frequency divider reduces the frequency and bandwidth of the other, allowing for simpler processing by separating signal paths for frequency and amplitude processing, and a modulator reintroduces amplitude information onto the frequency-divided signal, enabling efficient simulation of reflection signals without losing amplitude information.
This approach reduces the complexity and cost of signal processing, allowing for the use of slower components and enabling accurate simulation of radar cross sections by maintaining amplitude information, thus simplifying the simulation of reflection objects with different properties.
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Abstract
Description
[0001] Test device for testing a distance sensor operating with electromagnetic waves and a frequency divider arrangement for such a test device
[0002] The invention relates to a test device for testing a distance sensor operating with electromagnetic waves, with a receiving element for receiving an electromagnetic free-space wave as a received signal with a received frequency and a signal bandwidth, with a emitting element for emitting an electromagnetic output signal, wherein in simulation mode the received signal or a received signal derived from the received signal is converted into a sampled signal by means of an analog / digital converter, the sampled signal is time-delayed by a signal processing unit to a time-delayed sampled signal, the time-delayed sampled signal is converted into a simulated reflection signal by means of a digital / analog converter, wherein the simulated reflection signal or a simulated reflection signal derived from the simulated reflection signal is emitted as an output signal via the emitting element.Furthermore, the invention also relates to a frequency divider arrangement for the aforementioned test device.
[0003] Test devices of the aforementioned type for testing distance sensors are known from various fields of technology, for example, in the field of control unit development and testing, particularly in the automotive sector; reference is made, for example, to WO 2020 / 165191 A1. Another field of application is end-of-line test benches, i.e., devices used for product testing at the end of a production line, in this case, for testing distance sensors (EP 4109125 A1).
[0004] This involves testing distance sensors that operate with electromagnetic waves. Radar sensors are predominantly used in the automotive sector. However, distance sensors that operate with electromagnetic waves in a different frequency range, such as the visible light range, or that operate with electromagnetic radiation sources that emit electromagnetic waves with a long coherence length, such as in laser applications, can also be tested.
[0005] With test devices of this type, it is possible to simulate a reflective object at virtually any distance to the distance sensor under test. Distance sensors of the type considered here basically work in such a way that the electromagnetic waves they emit are reflected by a reflective object within the radiation 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 signal travel time can be determined directly (time-of-flight measurement), but is often done indirectly via clever signal analysis. While in the first case very short sensor signals, i.e. pulses, are often used, in the latter case extended transmission signals are usually used and the desired distance information is obtained from the frequency of the mixed signal consisting of the transmitted signal and the received reflection signal.Examples of temporally extended transmission signals are frequency-modulated continuous wave signals.
[0006] The test device is positioned in the radiation area of the distance sensor to test it. The test device receives the free-space waves emitted by the distance sensor and delays this reception signal with its signal processing unit according to a predetermined time delay. It then radiates the time-delayed signal via its radiating element towards the distance sensor to be tested, which gives the distance sensor the impression of a reflected object that has been removed according to the set time delay.
[0007] The ability to adjust a time delay is a minimum requirement for the test fixture, as it allows the fundamental property of the distance of the reflected object to be simulated. Advanced test fixtures can also simulate radial motion components relative to the distance sensor. Due to the Doppler effect, the reflected signals are frequency-shifted relative to the frequency of the transmitted signal from the distance sensor. Modern test fixtures are capable of applying appropriate frequency shifts to the simulated reflected signal relative to the frequency of the received signal in order to represent specified radial motion components in the simulated reflected signal. Even more advanced techniques can simulate complex Doppler signatures with multiple motion components.
[0008] On the input side, we speak of the received signal and the received signal derived from the received signal, and on the output side, we speak of the simulated reflection signal and the simulated reflection signal derived from the simulated reflection signal. The reason for this is simply that the originally received received signal may undergo upstream signal processing on its way to digital signal processing by the signal processing unit, so a strict distinction must be made between the received signal itself and the possibly intermediately processed received signal, which is then no longer the original received signal but the received signal derived from the received signal. This is exactly how things work in the signal path downstream of the digital signal processing.Here, too, it is possible that the simulated reflection signal also undergoes intermediate signal processing on its way to the emitting element, so that in strict terms it is not the simulated reflection signal that is emitted as the output signal, but rather the simulated reflection signal derived from the simulated reflection signal.
[0009] The hardware requirements for the test fixture and thus for the signal processing unit are extremely high. Distance sensors often operate in the 80 GHz range with a bandwidth of several GHz. A concrete example of a common application for a test fixture testing a distance sensor today is a reception frequency of 79 GHz (center frequency) with a bandwidth of 4 GHz, so that the received signal to be processed lies in a range of 77 to 81 GHz. It is readily apparent that capturing the received signal and processing it (sampling via analog / digital conversion, time delay, frequency shifting, applying complex Doppler signatures, digital / analog conversion) is extremely demanding, as processing times are in the nanosecond to microsecond range.
[0010] To simulate reflective objects with different reflection behavior, for example, due to different object sizes, different surface material properties, or different spatial orientations of reflective surfaces, it is also important, at least for testing distance sensors that also evaluate the amplitude of the reflection signal, that the simulated reflection signal has a signal amplitude that matches the size of the reflective object being simulated. In short, the simulated reflection signal should have an amplitude that corresponds to the radar cross-section of the object at a specific distance; however, for this to happen, the received signal amplitude must also be known.
[0011] The object of the present invention is to design and develop the described test device in such a way that the required signal processing is simplified.
[0012] The previously derived problem is solved in the test device described above in that the received signal is divided into a first partial received signal and a second partial received signal using a signal divider, wherein at least the second partial received signal contains the amplitude information of the received signal. When using known signal dividers, both partial received signals typically contain the amplitude information of the received signal. If it is stated that the second partial received signal contains the 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 certain ratio to the amplitude of the received signal, so that the information about the amplitude of the received signal can be determined by evaluating the amplitude of the second partial received signal.
[0013] The first partial received signal is converted by a frequency divider into a frequency-divided received signal that no longer contains the amplitude information of the received signal. The fact that the frequency-divided received signal no longer contains the amplitude information of the received signal (even if the first partial received signal still contains the amplitude information) is due to the fact that frequency dividers usually operate digitally and typically convert a sine wave into a square wave of the corresponding frequency, whose amplitude, however, merely alternates between a minimum and a maximum value.
[0014] The use of a frequency divider has two effects. Firstly, the received frequency is reduced by division according to the frequency divider's division factor. Secondly, the bandwidth of the received signal is reduced by the frequency divider's division factor. Both effects result in the subsequent signal processing (analog-to-digital conversion, digital signal processing by the signal processing unit, and digital-to-analog conversion) being significantly simplified and also more cost-effective to implement, as slower components can be used.
[0015] Furthermore, the amplitude information of the received signal is extracted from the second partial received signal using an amplitude detector. In the second partial received signal, the frequency of the received signal is not of interest, but rather solely its amplitude, which usually changes much more slowly than the oscillations of the received signal. Essentially, envelope detection is performed.
[0016] A modulator then generates a frequency-divided received signal with the amplitude information of the received signal. The amplitude information obtained from the second partial received signal is modulated onto the frequency-divided received signal without amplitude information. The frequency-divided received signal with the modulated amplitude information is then the received signal derived from the received signal, which is subsequently digitally processed.
[0017] By splitting the received signal into a first partial received signal and a second partial received signal, and by processing the partial received signals differently in the separated signal paths, once with regard to frequency and once with regard to amplitude, very simple signal processing can be implemented without any loss of amplitude information, which would be unavoidable if only one signal path with a frequency divider were used. This also allows the simulated reflection signal to be very easily adapted to a given radar cross-section of an assumed reflection object at a given distance to be simulated, which is not possible without knowledge of the amplitude of the received signal.
[0018] The test device further provides that the simulated reflection signal is converted by a frequency multiplier to the signal derived from the simulated reflection signal, i.e. the signal whose frequency has been reduced on the input side by the frequency divider is now increased again on the output side.
[0019] According to a preferred embodiment of the test device, the signal divider is implemented as a resistive power divider. This passive electrical solution is easy to implement and very reliable. It is also possible, in principle, to use active signal dividers or signal dividers based on a different principle.
[0020] A further advantageous embodiment of the test device is characterized by the digital implementation of the frequency divider, in particular based on bistable multivibrators. This solution is also reliable and simple and is also available as an integrated circuit. By connecting multivibrators in series, frequency dividers with a division factor corresponding to the inverse of a power of two can be easily implemented.
[0021] A preferred embodiment of the test device is characterized in that the amplitude detector is implemented with a rectifier and a downstream low-pass filter, in particular with a diode as the rectifier. This solution is also characterized by its electrically passive, simple, and reliable implementation.
[0022] In an advantageous development of the test device, the division factor of the frequency divider is selected such that the smallest frequency of the frequency-divided received signal is equal to or greater than the signal bandwidth of the received signal multiplied by half the division factor. If the division factor is 1 / x and the bandwidth of the received signal is B, then the frequency-divided received signal has a bandwidth of B / x. If the smallest frequency of the frequency-divided received signal f min, then the specified design rule is formulaically fmin > B / (2x). This design takes into account that the square-wave signals generated by frequency division have harmonics that are an odd multiple of the fundamental frequency. In the frequency divider implementation mentioned above, the first harmonic of the lowest frequency of the frequency-divided received signal is in a higher frequency range than the maximum frequency of the frequency-divided received signal and thus outside the frequency-divided bandwidth of the frequency-divided received signal.
[0023] In a further advantageous embodiment of the test device, a low-pass filter filters the frequency-divided received signal with the amplitude information, so that the fundamental harmonic of the frequency-divided received signal is obtained as the derived received signal. Filtering generates a harmonic signal from a square-wave signal or extracts the relevant harmonic of the fundamental frequency from a signal with many energy components in harmonics. The low-pass filter can also be arranged directly after the frequency divider, resulting in a harmonic signal without amplitude information. This harmonic signal can then be provided with amplitude information through modulation.
[0024] In an advantageous refinement of the test device, the cutoff frequency of the low-pass filter is between twice and three times the lowest frequency of the frequency-divided received signal. This is particularly useful if the division factor of the frequency divider is selected as described above.
[0025] In an advantageous embodiment of the test device and the frequency divider arrangement, a delay element is provided in the signal path between the signal divider via the frequency divider to the modulator and / or between the signal divider via the amplitude detector to the modulator. The delay element has a delay time such that the frequency-divided received signal and the amplitude information are combined in a timely manner. This compensates for different signal propagation times in the signal paths, starting from the signal divider.
[0026] In a further advantageous embodiment of the test device, the multiplication factor of the frequency multiplier corresponds to the inverse of the division factor of the frequency divider, whereby the simulated reflection signal is raised again to the reception frequency and the signal bandwidth of the simulated reflection signal is also extended to the signal bandwidth of the reception signal.
[0027] The frequency multiplier is preferably implemented using a semiconductor component with nonlinear transfer characteristics, which automatically generates harmonics. A diode or a transistor are suitable simple components. A bandpass filter is then preferably connected downstream of the frequency multiplier to filter or pass the harmonics in the desired frequency range.
[0028] In a further advantageous embodiment of the test device, the received signal is frequency-shifted toward lower frequencies using a receive converter, and the signal derived from the simulated reflection signal (i.e., after the frequency multiplier) is frequency-shifted toward higher frequencies using an output converter, with the frequency shifts being equal, in particular, on the input and output sides. The use of the receive converter and the output converter does not affect the signal bandwidth, but does lower or raise the frequency of the signal band. The frequency-shifted received signal would then be the input signal of the signal divider, previously referred to as the received signal.
[0029] The object described at the outset is also achieved with a frequency divider arrangement for a test device according to the invention.The frequency divider arrangement is characterized in that a received signal is divided by a signal divider into a first partial received signal and a second partial received signal, wherein at least the second partial received signal has the amplitude information of the received signal, that the first partial received signal is converted by a frequency divider into a frequency-divided received signal which no longer has the amplitude information of the received signal, that the amplitude information of the received signal is obtained from the second partial received signal using an amplitude detector, that a frequency-divided received signal with the amplitude information of the received signal is generated by a modulator in that the amplitude information obtained from the second partial received signal is modulated onto the frequency-divided received signal without amplitude information, thus generating a derived received signal from the received signal.The frequency divider arrangement is designed with regard to its components as previously described in connection with the test device.
[0030] In detail, there are now a multitude of possibilities for designing and developing the test device according to the invention and the frequency divider arrangement according to the invention. Reference is made, on the one hand, to the
[0031] independent patent claims, and on the other hand to the following description of embodiments in conjunction with the drawing. In the drawing,
[0032] Fig. 1 shows schematically a test device for testing a distance sensor operating with electromagnetic waves as known from the prior art,
[0033] Fig. 2 schematically shows amplitude spectra of the received signal and the received signal derived from the received signal, also as known from the prior art,
[0034] Fig. 3 shows a frequency divider arrangement as implemented in the reception path of the test device according to the invention,
[0035] Fig. 4 schematically shows a frequency multiplier in the output path of the test device according to the invention,
[0036] Fig. 5 schematically shows another embodiment of a frequency divider arrangement of the test device,
[0037] Fig. 6 schematically shows another embodiment of a frequency divider arrangement in the test device,
[0038] Fig. 7 shows a schematic diagram of a test device with input and output frequency converter and
[0039] Fig. 8 schematically shows amplitude spectra of different signals when using the frequency divider arrangement in the test device.
[0040] Fig. 1 shows a test 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 sector. The distance sensor 2 emits a free-space wave that is reflected by a reflective object and receives the reflection signal. From the time delay, a frequency shift, and possibly the signal intensity of the reflection signal, the distance sensor can deduce the distance to the reflective object, the radial velocity components of the reflective object, and possibly the size, reflection properties, etc. of the reflective object; this depends on the design of the distance sensor 2. The test device 1 simulates an actual reflective object to the distance sensor 2 under test.
[0041] The test device 1 has a receiving element 3 for receiving the electric free-space wave emitted by a distance sensor 2 as a received signal SRX. The received signal SRX has a received frequency fRx and a signal bandwidth B. Furthermore, the test device 1 has a radiating element 4 for radiating an electromagnetic output signal STX.
[0042] In simulation mode, the received signal SRX or a received signal S'RX derived from the received signal SRX 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 the simulated reflection signal S by means of a digital / analog converter 7. s The simulated reflection signal S sim or a simulated reflection signal S' derived from the simulated reflection signal Ssim sim is then radiated as output signal STX via the radiating element 4.
[0043] The signal processing unit 6 implements the necessary measures to impart all essential signal properties to the simulated reflection signal, i.e. a desired signal delay, a desired frequency shift (or several signal components with different frequency shifts) and, if applicable, also the desired amplitude of the simulated reflection signal Ssim.
[0044] Furthermore, as indicated in Fig. 1, there may be a signal processing unit 8a upstream on the input side and a signal processing unit 8b downstream on the output side of the signal processing unit 6. For example, it is known to downmix the received signal SRX to a lower frequency range using an input mixer while maintaining the signal bandwidth. This results in the received signal S'RX derived from the received signal SRX. This situation is illustrated in Fig. 2 using an amplitude spectrum. The received signal SRX has a bandwidth B of 4 GHz at a received frequency fRx of 79 GHz. The signal bandwidth B thus extends from 77 GHz to 81 GHz.By using a mixer, which is part of the upstream signal processing 8a on the input side, the received signal SRX is downconverted to an intermediate frequency of 4 GHz using a local oscillator frequency of 75 GHz, while maintaining the signal bandwidth B. In this example, the received signal S'RX is derived from the received signal SRX.
[0045] What is not explicitly shown is that the downstream signal processing 8b uses a corresponding mixer with which the low-frequency simulated reflection signal S s im is converted back up to the range of the received frequency fRx and then radiated as a derived simulated reflection signal S'sim. Since the bandwidth B of the received signal SRX remains unchanged, the signal sampling requirements, which depend on the signal bandwidth B, remain unchanged and remain high.
[0046] Figures 3 to 8 describe various aspects of a test device 1 according to the invention for testing the distance sensor 2 operating with electromagnetic waves, as well as a frequency divider arrangement 9 according to the invention, which is a component of the test device 1.
[0047] Fig. 3 initially shows a frequency divider arrangement 9, which is a component of the signal processing upstream on the input side. It can be seen that the received signal SRX is divided by a signal divider 10 into a first partial received signal Si 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 SRX. In the present case, the signal divider 10 is a resistive power divider, so that the first partial received signal Si also basically has the amplitude information A of the received signal SRX. The first partial received signal Si is converted by a frequency divider 11 into a frequency-divided received signal Sif that no longer has the amplitude information A of the received signal SRX.The frequency-divided received signal Sif does not have the amplitude information A because the frequency divider 11 outputs a digital output signal which still has the frequency information but no longer contains the amplitude information of the frequency-divided input signal.
[0048] The amplitude information A of the received signal SRX is obtained from the second partial received signal S2 using an amplitude detector 12. In this case, the envelope of the second partial received signal S2 is detected.
[0049] Finally, a modulator 13 generates a frequency-divided received signal SfA with the amplitude information A of the received signal SRX by modulating the amplitude information A obtained from the second partial received signal S2 onto the frequency-divided received signal without amplitude information Sif. In this way, the received signal S'RX derived from the received signal SRX is generated. With the described frequency divider arrangement 9, it is possible to cleverly compensate for the loss of the amplitude information A when using a frequency divider 11 by recovering the amplitude information A in a separate signal path and modulating it again onto the frequency-divided received signal Sif, which no longer has the amplitude information A.The use of the frequency divider 11 has the advantage that not only the reception frequency fRx, i.e. the center frequency of the reception signal SRX, is reduced by the division factor 1 / x of the frequency divider 11, but that the signal bandwidth B of the reception signal SRX is also reduced by the same factor, so that the requirements for further signal processing are correspondingly lower.
[0050] In Fig. 4, a further aspect of the test device 1 is shown, namely that the simulated reflection signal S sim with a frequency multiplier 14 to that of the simulated reflection signal S s in the derived signal S'sim. In this case, the multiplication factor y of the frequency multiplier 14 is equal to the inverse of the division factor 1 / x of the frequency divider 11. This exactly cancels out the effects of the frequency divider 11 (reduction of the center frequency and reduction of the bandwidth).
[0051] In the illustrated embodiments, the frequency divider 11 is implemented digitally, namely on the basis of fast bistable flip-flops.
[0052] In the illustrated embodiments, the amplitude detector 12 is realized with a rectifier and a downstream low-pass filter, namely - not shown individually in detail - with a diode as a rectifier.
[0053] Fig. 5 shows that the frequency divider 11 is followed by a low-pass filter 18, which passes only the fundamental harmonic of the frequency-divided received signal without amplitude information Sif. This allows the square-wave signal resulting from the frequency division to be easily converted into a clean sine wave.
[0054] Fig. 6 shows an alternative implementation of the test device 1 or the frequency divider arrangement 9, in which the low-pass filter 18 filters the frequency-divided received signal with the amplitude information SfASO so that only the harmonic fundamental oscillation of the frequency-divided received signal SfA results as the derived received signal S'RX.
[0055] In both of the aforementioned embodiments according to Figures 5 and 6, the low-pass filter 18 is designed such that its cutoff frequency lies between twice and three times the smallest frequency of the frequency-divided received signal Sif, SfA.
[0056] The embodiments also have in common that the multiplication factor y of the frequency multiplier 14 corresponds to the inverse of the division factor x of the frequency divider 11, whereby the frequency shifts as well as the bandwidth reduction and the bandwidth expansion on the input side and output side cancel each other out.
[0057] Although not shown in detail, the test devices 1 in the exemplary embodiments have in common that the frequency multiplier 14 is implemented using a diode to generate harmonics. A bandpass filter is connected downstream to filter a harmonic, in this case the one with four times the fundamental frequency.
[0058] Fig. 7 shows a test device 1 in which the received signal SRX is frequency-shifted toward lower frequencies by a receive converter 15, and in which the output signal of the frequency multiplier 14 is shifted toward higher frequencies by an output converter 16, the frequency shifts being equal in magnitude here. The receive converter 15 and the output converter 16 are mixers to which a local oscillator 17 applies a harmonic signal with a corresponding frequency for increasing and decreasing the respective frequency of the input signal. The received signal SRX is already frequency-shifted here before it is further processed by the frequency divider arrangement 9 in the manner described. In order to avoid having to use further designations, it will nevertheless be referred to as the received signal SRX.
[0059] Fig. 8 shows the amplitude spectrum of various signals resulting from the use of the frequency divider arrangement 9 in the test device 1 according to Fig. 7. Here, too, the received signal SRX has a bandwidth B of 4 GHz with a center frequency of 79 GHz. The receive converter 15 is fed by the local oscillator 17 with a mixing frequency of 75 GHz, so that the reduced received signal SRX with the unchanged bandwidth B of 4 GHz results in the range from 2 to 6 GHz. This signal is fed to the frequency divider arrangement 9, with the frequency divider 11 used having a division factor of 1 / x = 1 / 4. The bandwidth B is therefore reduced by a factor of 4, i.e., to 1 GHz. The limiting frequencies are also reduced by a factor of 4 and are now 0.5 GHz and 1.5 GHz.When choosing the division factor 1 / x, care was taken to ensure that the smallest frequency of the frequency-divided received signal Sif is equal to or greater than the signal bandwidth B of the received signal multiplied by half the division factor 1 / x, i.e. multiplied by l / (2x).
[0060] The bandwidth-reduced (B / x) receive signal S'RX derived from the receive signal SRX is easier to handle by the subsequent digital signal processing than a signal with the original, larger bandwidth B. Therefore, the use of less fast power electronic components is possible, which enables the use of less sophisticated and thus often cheaper hardware components.
[0061] Reference symbol
[0062] 1 test device
[0063] 2 distance sensors
[0064] 3 Receiving element
[0065] 4 From beam element
[0066] 5 analog / digital converters
[0067] 6 Signal processing unit
[0068] 7 Digital / analog converter 8a input-side upstream signal processing 8b output-side downstream signal processing
[0069] 9 Frequency divider arrangement
[0070] 10 signal splitters
[0071] 11 frequency dividers
[0072] 12 Amplitude detector
[0073] 13 Modulator
[0074] 14 frequency multipliers
[0075] 15 receive converters
[0076] 16 output converters
[0077] 17 Local oscillator
[0078] 18 low-pass filters
[0079] SRX Receive signal fx Receive frequency B Bandwidth of the receive signal S'RX Receive signal derived from the receive signal SRX STX Output signal
[0080] Ssim simulated reflection signal S'sim derived simulated reflection signal
[0081] S1, S2first, second partial received signal A amplitude information Sif frequency-divided received signal without amplitude information SfA frequency-divided received signal with modulated
[0082] Amplitude information
[0083] 1 / x Division factor of the frequency divider y Multiplication factor of the frequency multiplier
Claims
Patent claims 1. Test device (1) for testing a distance sensor (2) operating with electromagnetic waves, with a receiving element (3) for receiving an electromagnetic free-space wave as a received signal (SRX) with a received frequency (fRx) and a signal bandwidth (B), with a radiating element (4) for radiating an electromagnetic output signal (STX), wherein in simulation mode the received signal (SRX) or a received signal (S'RX) derived from the received signal (SRX) 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, the time-delayed sampled signal is converted into a simulated reflection signal (Ssim) by means of a digital / analog converter (7),wherein the simulated reflection signal (Ssim) or a simulated reflection signal (S'sim) derived from the simulated reflection signal (Ssim) is emitted as an output signal (STX) via the emitting element (4), characterized in that the received signal (SRX) is divided by a signal divider (10) into a first partial received signal (Si) 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 (SRX), that the first partial received signal (Si) is converted by a frequency divider (11) into a frequency-divided received signal (Sif) no longer having the amplitude information (A) of the received signal (SRX), that from the second partial received signal (S2) by an amplitude detector (12) the Amplitude information (A) of the received signal (SRX) is obtained,that a frequency-divided received signal (SfA) with the amplitude information (A) of the received signal (SRX) is generated by a modulator (13) by applying to the frequency-divided received signal without amplitude information (S if) the amplitude information from the two-, th partial received signal (S2) is modulated onto the amplitude information (A) and thus the received signal (S'RX) derived from the received signal (SRX) is generated, and that the simulated reflection signal (Ssim) is converted by a frequency multiplier (14) to the signal (S sim ) derived from the simulated reflection signal (Ssim).
2. Test device (1) according to claim 1, characterized in that the signal divider (10) is realized as a resistive power divider.
3. Test device (1) according to claim 1 or 2, characterized in that the frequency divider (11) is implemented digitally, in particular on the basis of bistable flip-flops.
4. Test device (1) according to one of claims 1 to 3, characterized in that the amplitude detector (12) is realized with a rectifier and a downstream low-pass filter, in particular with a diode as a rectifier.
5. Test device (1) according to one of claims 1 to 4, characterized in that the division factor (1 / x) of the frequency divider (11) is selected such that the smallest frequency of the frequency-divided received signal (S if) is equal to or greater than the signal bandwidth (B) multiplied by half the division factor (1 / x).
6. Test device (1) according to one of claims 1 to 5, characterized in that a low-pass filter (18) filters the frequency-divided received signal with the amplitude information (SfA) so that the fundamental harmonic of the frequency-divided received signal (SfA) is obtained as a derived received signal (S'RX).
7. Test device (1) according to claim 6, characterized in that the cutoff frequency of the low-pass filter (18) is between twice and three times the smallest frequency of the frequency-divided received signal (Sif, SfA).
8. Test device (1) according to one of claims 1 to 6, characterized in that the multiplication factor (y) of the frequency multiplier (14) corresponds to the inverse of the division factor (1 / x) of the frequency divider (11).
9. Test device (1) according to one of claims 1 to 8, characterized in that the frequency multiplier (14) is implemented using a half- conductor component with non-linear transmission behavior is realized for generating harmonic waves, in particular using a diode or a transistor.
10. Test device (1) according to one of claims 1 to 9, characterized in that the received signal (SRX) is frequency-shifted to lower frequencies by a receive converter (15) and that the output signal of the frequency multiplier (14) is shifted to higher frequencies by an output converter (16), in particular wherein the frequency shifts are of equal magnitude.
11. Frequency divider arrangement (9) for a test device (1) according to one of claims 1 to 10, characterized in that a received signal (SRX) is divided by a signal divider (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 (SRX), that the first partial received signal (S1) is converted by a frequency divider (11) into a frequency-divided received signal (S1 if) no longer has the amplitude information (A) of the received signal (SRX), that the amplitude information (A) of the received signal (SRX) is obtained from the second partial received signal (S2) by an amplitude detector (12), that a frequency-divided received signal (SfA) is generated with the amplitude information (A) of the received signal (SRX),by modulating the amplitude information (A) obtained from the second partial received signal (S2) onto the frequency-divided received signal (S if) without amplitude information (A), thus generating a derived received signal (SRX) from the received signal (SRX).
12. Frequency divider arrangement (9) according to claim 11, characterized by the features of the characterizing part of at least one claim of claims 2 to 7.