Inspection device for testing distance sensors operating with electromagnetic waves and frequency division device for such an inspection device - Patents.com
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- DSPACE DIGITAL SIGNAL PROCESSING & CONTROL ENGINEERING GMBH
- Filing Date
- 2023-12-04
- Publication Date
- 2026-07-23
Smart Images
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Abstract
Description
[Technical Field]
[0001] The present invention relates to an inspection device for testing distance sensors operating with electromagnetic waves, the inspection device comprising a receiving element for receiving free-space electromagnetic waves as a received signal having a predetermined receiving frequency and a predetermined signal bandwidth, 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 converted into a sampling signal by an analog-to-digital converter, the sampling signal is time-delayed by a signal processing unit into a time-delayed sampling signal, the time-delayed sampling signal is converted into a simulated reflected signal by a digital-to-analog converter, and the simulated reflected signal or a simulated reflected signal derived therefrom is radiated as an output signal via the radiating element. The present invention further relates to a frequency division device for the inspection device described above. [Background technology]
[0002] Test devices of the above-mentioned type for testing distance sensors are known from various technical fields, for example from the field of control device development and testing, in particular in the automotive field, see, for example, WO 2020 / 165191. Another field of application is EOL test benches, i.e. devices used for product testing at the end of the production line, in this case devices used for testing distance sensors (EP 4109125 A1).
[0003] The above mentioned document discusses the testing of distance sensors that operate with electromagnetic waves, and in the automotive sector the use of radar sensors is very common, but in principle it is also possible to test distance sensors that operate with electromagnetic waves in other frequency ranges, for example in the visible light range, or that operate with electromagnetic radiation sources that emit electromagnetic waves with a longer coherence length.
[0004] This type of inspection device makes it possible to simulate a reflecting object at virtually any distance relative to the distance sensor being tested. Distance sensors operating in the manner considered here essentially operate by emitting electromagnetic waves that are reflected by a reflecting object within the sensor's radiation range, receiving the reflected waves, and determining the distance to the object from the wave's transit time. The signal transit time can be determined directly (time-of-flight measurement), but more often indirectly through sophisticated signal evaluation. In the former case, very short sensor signals, or impulses, are often used, while in the latter case, a time-stretched transmitted signal is often used, and the desired distance information is obtained from the frequency of the mixed signal consisting of the transmitted signal and the received reflected signal. An example of a time-stretched transmitted signal is a frequency-modulated continuous wave signal.
[0005] The inspection device is arranged in the emitting area of the distance sensor to test the distance sensor, receives the free space wave emitted from the distance sensor, delays the received signal according to a time delay set by a signal processing unit, and then radiates the time-delayed signal again via the emitting element toward the distance sensor to be tested, thereby creating an impression in the distance sensor of a reflective object that is a distance away according to the set time delay.
[0006] The adjustable time delay is the minimum requirement for the inspection device, since it allows the simulation of the basic characteristics of the distance to the reflecting object. Advanced inspection devices can also simulate a radial motion component relative to the distance sensor. In this case, based on the Doppler effect, the reflected signal is frequency shifted with respect to the frequency of the transmitted signal sent from the distance sensor. Current inspection devices can perform a corresponding frequency shift of the simulated reflected signal with respect to the frequency of the received signal, thereby simulating a set radial motion component in the simulated reflected signal. More advanced technology can also simulate complex Doppler signatures with multiple motion components.
[0007] The input side handles the received signal and a received signal derived from the received signal, while the output side handles the simulated reflected signal and a simulated reflected signal derived from the simulated reflected signal.The background to this is that the original received signal passes through a signal processing unit and possibly further upstream signal processing units on its way to the digital signal processing unit, so it is necessary to strictly distinguish between the received signal itself and the received signal that has undergone intermediate processing depending on the situation, which is no longer the original received signal but a received signal derived from the received signal.Strictly speaking, an object is supported in the signal path downstream of the digital signal processing unit.In this case, the simulated reflected signal may also undergo intermediate signal processing on its way to the radiating element, so strictly speaking, it is not the simulated reflected signal that is radiated as the output signal, but rather a simulated reflected signal derived from the simulated reflected signal.
[0008] The hardware requirements for the test equipment and thus for the signal processing unit are extremely high. Distance sensors often operate in the 80 GHz range with a bandwidth of several gigahertz. A concrete example of a typical application today in test equipment for testing distance sensors is a receive frequency of 79 GHz (center frequency) with a bandwidth of 4 GHz, with the received signals to be processed in the range of 77-81 GHz. It can be easily seen that the detection of the received signal and its processing (sampling by analog-to-digital conversion, time delay, frequency shift, application of complex Doppler signature, digital-to-analog conversion) require extremely high processing times in the nanosecond to microsecond range.
[0009] In testing distance sensors that evaluate the amplitude of a reflected signal, for example to simulate reflecting objects with reflection characteristics based on different object sizes, different surface material properties, or different spatial orientations of the reflecting surfaces, it is important that the simulated reflected signal has a signal amplitude that matches the size of the reflecting object to be simulated. That is, the simulated reflected signal should have an amplitude that corresponds to the radar cross section of an object at a specific distance, but for this the amplitude of the received signal must also be known. Summary of the Invention [Problem to be solved by the invention]
[0010] The object of the invention is to design and develop the above-mentioned testing device in such a way that the necessary signal processing is simplified. [Means for solving the problem]
[0011] The above-mentioned problem is solved in the testing device mentioned at the beginning by dividing the received signal into a first partial received signal and a second partial received signal by a signal splitter, wherein at least the second partial received signal contains amplitude information of the received signal. When known signal splitters are used, the two partial received signals usually contain amplitude information of the received signal. When the second partial received signal contains amplitude information of the received signal, it does not necessarily have to contain 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 information about the amplitude of the received signal can be determined by evaluating the amplitude of the second partial received signal.
[0012] The first partial received signal is converted by the frequency divider into a frequency-divided received signal that no longer has the amplitude information of the received signal (even if the first partial received signal still has amplitude information), because the frequency divider often operates digitally to form from the sinusoidal oscillations a square-wave signal with a normally corresponding frequency, the amplitude of which varies only reciprocally between a minimum and a maximum value.
[0013] The use of a frequency divider has two effects: on the one hand, the received frequency is down-divided according to the division factor of the frequency divider; on the other hand, the bandwidth of the received signal is also reduced by the division factor of the frequency divider. As a result of both of these effects, the subsequent signal processing (analog / digital conversion, digital signal processing by a signal processing unit and digital / analog conversion) is significantly simplified and slower components can be used, which also allows for a more cost-effective implementation.
[0014] Furthermore, the amplitude detector obtains amplitude information of the received signal from the second partial received signal, i.e., the frequency of the received signal is not of interest in the second partial received signal, but rather the amplitude of the received signal, which often changes much more slowly than the oscillations of the received signal. In other words, envelope detection is basically performed.
[0015] The modulator modulates the amplitude information obtained from the second partial received signal onto the frequency-divided received signal without amplitude information to form a frequency-divided received signal with the amplitude information of the received signal. In this case, the frequency-divided received signal with the modulated amplitude information is a received signal derived from the received signal, which is subsequently further digitally processed.
[0016] By dividing the received signal into a first partial received signal and a second partial received signal and processing the partial received signals differently in the divided signal paths, i.e., once in terms of frequency and once in terms of amplitude, signal processing can be performed very easily, especially without the loss of amplitude information that would be unavoidable if only one signal path with one frequency divider were used. This also makes it very easy to adapt the simulated reflected signal to a set radar cross section of an assumed reflecting object at a set distance to be simulated, which would not be possible without knowledge of the amplitude of the received signal.
[0017] In the inspection device, the simulated reflected signal is further converted by a frequency multiplier into a signal derived from the simulated reflected signal, i.e., the signal reduced in frequency by a frequency divider on the input side is again upconverted in frequency here on the output side.
[0018] In a preferred configuration of the test device, the signal divider is realized as a resistive power divider. This electrically passive means is easy to implement and very reliable. In principle, active signal dividers or signal dividers based on other principles can also be used.
[0019] Another advantageous embodiment of the test device is characterized in that the frequency divider is realized digitally, in particular on the basis of bistable flip-flops. This solution is also reliable, simple, and available as an integrated circuit. By connecting flip-flops in series, it is easy to realize frequency dividers, in particular with division factors corresponding to the inverse of a power of two.
[0020] A preferred embodiment of the test device is therefore characterized in that the amplitude detector is realized by a rectifier and a downstream low-pass filter, in particular by a diode as rectifier, which is likewise advantageous in that it is electrically passive and can be realized simply and reliably.
[0021] In an advantageous development of the test device, the division factor of the frequency divider is selected so that the minimum frequency of the frequency-divided received signal is equal to or greater than the signal bandwidth of the received signal multiplied by a division factor of 1 / 2. 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 minimum frequency of the frequency-divided received signal is f min If so, the proposed selection rule is min >B / (2x). This selection takes into account that the square wave signal formed by frequency division has harmonics with odd multiples of the fundamental frequency. In the above-described frequency divider implementation, the first harmonic of the minimum frequency of the frequency-divided received signal is in a higher frequency region than the maximum frequency of the frequency-divided received signal, and is therefore outside the frequency-division bandwidth of the frequency-divided received signal.
[0022] In another advantageous configuration of the inspection device, a low-pass filter filters the frequency-divided received signal with amplitude information, thereby obtaining the fundamental vibrations of the harmonics of the frequency-divided received signal as the derived received signal. The filtering allows the generation of harmonic signals from square-wave signals or the extraction of interesting harmonics of the fundamental frequency from signals with a high energy content of harmonic vibrations. The low-pass filter can be arranged directly after the frequency divider, thereby obtaining harmonic signals without amplitude information, which are provided with amplitude information by modulation.
[0023] In an advantageous development of the test device, the cutoff frequency of the low pass is between two and three times the minimum frequency of the frequency-divided received signal, which is particularly advantageous when the division factor of the frequency divider is selected as described above.
[0024] In one advantageous configuration of the test device and the frequency dividing device, a delay element is provided in the signal path between the signal divider and the frequency divider via the frequency divider to the modulator and / or between the signal divider via the amplitude detector to the modulator, the delay element having a delay time that ensures that the frequency-divided received signal and the amplitude information are combined in a timely manner, thereby compensating for different signal transit times in the signal path starting from the signal divider.
[0025] In another advantageous configuration of the inspection device, the multiplication factor of the frequency multiplier corresponds to the reciprocal of the division factor of the frequency divider, whereby the simulated reflected signal is increased again to the received frequency and the signal bandwidth of the simulated reflected signal is also expanded to the signal bandwidth of the received signal.
[0026] Preferably, the frequency multiplier is realized using semiconductor components with nonlinear transmission characteristics, which automatically generate harmonics. Simple components such as diodes or transistors are also possible. In this case, a bandpass filter is preferably connected downstream of the frequency multiplier to filter or pass the harmonics in the desired frequency range.
[0027] In another advantageous configuration of the test device, the received signal is frequency-shifted to a lower frequency by a receiving converter, and the signal derived from the simulated reflected signal (i.e., after the frequency converter) is frequency-shifted to a higher frequency by an output converter, whereby the frequency shifts are equal in absolute value on the input and output sides. The use of the receiving and output converters does not affect the signal bandwidth, but the frequency of the signal band is down- or multiplied. In other words, the frequency-shifted received signal is in this case the input signal of the signal splitter, which was previously referred to as the received signal.
[0028] The problem set forth above is also solved by a frequency division device for a testing device according to the present invention, characterized in that a received signal is divided by a signal divider into a first partial received signal and a second partial received signal, at least the second partial received signal having amplitude information of the received signal, the first partial received signal is converted by a frequency divider into a frequency-divided received signal that no longer has the amplitude information of the received signal, an amplitude detector obtains the amplitude information of the received signal from the second partial received signal, and a modulator superimposes the amplitude information obtained from the second partial received signal onto the frequency-divided received signal without amplitude information, thereby forming a received signal derived from the received signal, thereby forming a frequency-divided received signal having the amplitude information of the received signal. The frequency division device is designed as described above in relation to the testing device with regard to its components.
[0029] In particular, there are several means for constructing and developing the test device according to the invention and the frequency division device according to the invention, for which reference is made on the one hand to the claims dependent on the independent claims and on the other hand to the following description of exemplary embodiments in conjunction with the drawings, in which: [Brief explanation of the drawings]
[0030] [Figure 1] 1 shows a schematic diagram of a testing device known from the prior art for testing distance sensors operating with electromagnetic waves; [Figure 2] 1 shows a schematic diagram of a received signal and an amplitude spectrum of the received signal derived therefrom, as known from the prior art; [Figure 3] 1 shows a frequency division device implemented in the receive path of a test device according to the invention; [Figure 4] 2 shows a schematic diagram of a frequency multiplier in the output path of a test device according to the invention; [Figure 5] FIG. 10 is a diagram illustrating another embodiment of a frequency division device of the inspection device. [Figure 6]FIG. 10 is a schematic diagram illustrating another embodiment of a frequency division device in an inspection device. [Figure 7] 1 shows a schematic diagram of an inspection device with input and output frequency converters; [Figure 8] 10A and 10B are diagrams illustrating the amplitude spectra of various signals when a frequency division device is used in an inspection device; DETAILED DESCRIPTION OF THE INVENTION
[0031] FIG. 1 shows a test device 1 for testing a distance sensor 2 operating with electromagnetic waves, as known from the prior art. The distance sensor 2 is, for example, a radar distance sensor used in the automotive sector. The distance sensor 2 emits free-space waves and receives a reflected signal that is reflected by a reflecting object. From the time delay, frequency shift, and possibly signal strength of the reflected signal, the distance sensor can deduce the distance to the reflecting object, the radial velocity component of the reflecting object, and possibly the size and reflection characteristics of the reflecting object, all of which depend on the configuration of the distance sensor 2. The test device 1 simulates a real reflecting object for the distance sensor 2 to be tested.
[0032] The inspection device 1 receives a free space radio wave emitted from the distance sensor 2 as a reception signal S RX The receiving element 3 receives the received signal S RX is the given receiving frequency f RX and a predetermined signal bandwidth B. Furthermore, the inspection device 1 generates an electromagnetic output signal S TX The antenna has a radiating element 4 that radiates a
[0033] During simulation, the received signal S RX Or the received signal S RX The received signal S' is derived from RX is converted by an analog-to-digital converter 5 into a sampling signal, which is time-delayed by a signal processing unit 6 into a time-delayed sampling signal, which is converted by a digital-to-analog converter 7 into a simulated reflection signal Ssim In this case, the simulated reflected signal S sim or the simulated reflected signal S sim The simulated reflected signal S' derived from sim is the output signal S TX is radiated through the radiating element 4 as
[0034] The signal processing unit 6 processes the simulated reflected signal by all important signal characteristics, i.e. the desired signal delay, the desired frequency shift (or a plurality of signal components each differently frequency shifted) and possibly the simulated reflected signal S sim The necessary measures are then taken to give the desired amplitude of
[0035] Furthermore, as shown in Fig. 1, there may be a signal processing section 8a at the input side and a signal processing section 8 at the output side for signal processing in the signal processing unit 6. For example, the received signal S RX It is known to downmix the received signal S to a lower frequency range by an input mixer while maintaining its bandwidth. RX Based on the received signal S RX The received signal S' is derived from RX This situation is illustrated in Figure 2 based on the amplitude spectrum of the received signal S RX is the receiving frequency f of 79 GHz RX The received signal S has a bandwidth B of 4 GHz. That is, the signal bandwidth B extends from 77 GHz to 81 GHz. By using a mixer, which is a component of the signal processing unit 8a located at the input side, the received signal S RX is downmixed to a 4 GHz intermediate frequency using the 75 GHz frequency of the local oscillator, while still maintaining the signal bandwidth B. Thus, in this example, the received signal S RX The received signal S' is derived from RX is obtained.
[0036] Although not shown in detail, a corresponding mixer is used in the signal processing unit 8b downstream on the output side, which mixer generates a low-frequency simulated reflection signal S sim is again the receiving frequency f RX and then the derived simulated reflected signal S' sim The received signal S RX Since the bandwidth B of the signal remains unchanged, the requirements for sampling the signal, which depend on the signal bandwidth B, are maintained and remain unchanged.
[0037] 3 to 8 show various aspects of an inspection device 1 according to the present invention for testing a distance sensor 2 that operates with electromagnetic waves, and a frequency division device 9 according to the present invention that is a component of the inspection device 1.
[0038] 3 shows firstly the frequency division device 9, which is a component of the signal processing section located before the input side. RX is split into a first partial received signal S1 and a second partial received signal S2 by a signal splitter 10, where at least the second partial received signal S2 is RX In this case, since the signal divider 10 is a resistive power divider, the first partial received signal S1 also basically has amplitude information A of the received signal S RX The first partial received signal S1 has amplitude information A of the received signal S RX The frequency-division received signal S no longer has the amplitude information A. 1f Therefore, the frequency-division received signal S 1f does not contain the amplitude information A because the frequency divider 11 outputs a digital output signal that still contains frequency information but no longer contains amplitude information of the frequency-divided input signal.
[0039] From the second partial received signal S2, the amplitude detector 12 detects the received signal S RX In this case, the envelope of the second partial received signal S2 is detected.
[0040] Finally, the modulator 13 generates the frequency-divided received signal S without amplitude information. 1f The amplitude information A obtained from the second partial received signal S2 is superimposed on the received signal S RX The frequency division received signal S has amplitude information A of fA In this way, the received signal S RX The received signal S' is derived from RX The above-mentioned frequency division device 9 recovers the amplitude information A in a separate signal path, resulting in a received signal S which has been frequency divided but no longer contains the amplitude information A. 1f The loss of amplitude information A when using frequency divider 11 can be compensated for again in a clever way by again superimposing modulation on the received frequency f RX That is, the received signal S RX Not only is the center frequency of the received signal S down-converted by the division factor 1 / x of the frequency divider 11, but RX Advantageously, the signal bandwidth B is also reduced by the same factor, so the demands on further signal processing are correspondingly lower.
[0041] FIG. 4 shows another embodiment of the inspection device 1, namely, a frequency multiplier 14 for generating a simulated reflected signal S sim is the simulated reflected signal S sim The signal S' derived from sim where the multiplication factor y of frequency multiplier 14 is equal to the reciprocal of the division factor 1 / x of frequency divider 11. This exactly cancels the effect of frequency divider 11 (down-converting the center frequency and reducing the bandwidth).
[0042] In the embodiment shown, the frequency divider 11 is realized in digital technology, i.e. based on a fast bistable flip-flop.
[0043] In the illustrated embodiment, the amplitude detector 12 is realized by a rectifier and a downstream low pass, in particular by a diode as rectifier (not shown in detail separately).
[0044] In FIG. 5, the frequency divider 11 is followed by a low-pass filter 18, which receives the frequency-divided received signal S without amplitude information. 1f It has been shown that the frequency division technique transmits only the fundamental vibration of the harmonics of the square wave signal, so that the square wave signal obtained from the frequency division can be easily converted into a sinusoidal vibration.
[0045] In FIG. 6 an alternative implementation of the test device 1 or frequency division device 9 is shown, in which the frequency-divided received signal S fA The received signal S' is derived from only the fundamental vibration of the harmonics of RX The low-pass filter 18 receives the frequency-divided received signal S fA Filter the.
[0046] In the two embodiments shown in FIGS. 5 and 6, the low-pass filter 18 has a cutoff frequency that is equal to the cutoff frequency of the frequency-divided received signal S 1f ,S fA The frequency is configured to be between two and three times the minimum frequency of the
[0047] In these embodiments, the multiplication coefficient y of the frequency multiplier 14 corresponds to the reciprocal x of the division coefficient of the frequency divider 11, so that the frequency shift, bandwidth reduction, and bandwidth expansion are all canceled out on the input and output sides.
[0048] Although not shown in detail, these test devices 1 have in common that the frequency multiplier 14 is implemented using diodes to generate harmonics, followed by a bandpass filter to filter out the harmonics, in this case the fourth harmonic of the fundamental frequency.
[0049] In Figure 7, the received signal S RXis frequency-shifted to a lower frequency by the receiving converter 15, and the output signal of the frequency multiplier 14 is frequency-shifted to a higher frequency by the output converter 16, where it is shown that the absolute values of the frequency shifts are equal in this case. The receiving converter 15 and the output converter 16 are mixers to which harmonic signals having corresponding frequencies for multiplying and down-converting the frequencies of the input signal are applied from a local oscillator 17. The receiving signal S RX has now already been frequency shifted and is then further processed as described above by the frequency division device 9. Note that this signal is also used as the received signal S RX It is called.
[0050] 8 shows the amplitude spectrum of the various signals that arise when using the frequency division device 9 in the test device 1 according to FIG. 7. Here again, the received signal S RX has a bandwidth B of 4 GHz at a center frequency of 79 GHz. The receiving transducer 15 is supplied with a mixed frequency of 75 GHz from a local oscillator 17, which produces a down-converted received signal S having a bandwidth B of 4 GHz in the range of 2 to 6 GHz. RX This signal is fed to a frequency division device 9, in which the frequency divider 11 used has a division factor 1 / x=1 / 4. The bandwidth B is therefore reduced by a factor of 4, i.e. to 1 GHz. The cutoff frequencies are likewise reduced by a factor of 4, now to 0.5 GHz and 1.5 GHz. When the division factor 1 / x is chosen, the frequency-divided received signal S 1f It should be noted that the minimum frequency of is equal to or greater than the signal bandwidth B of the received signal multiplied by 1 / 2 of the division factor 1 / x, i.e., 1 / (2x).
[0051] Received signal S RX The received signal S' is derived from the RXcan be more easily handled by subsequent digital signal processing than the original signal with a larger bandwidth B. Therefore, less fast power electronic components can be used, which in turn allows the use of less demanding and therefore often cheaper hardware components. [Explanation of symbols]
[0052] 1. Inspection equipment 2 distance sensors 3 receiving element 4 Radiating elements 5 Analog-to-Digital Converter 6 Signal Processing Unit 7 Digital / Analog Converter 8a Signal processing unit located in front of the input side 8b Signal processing section placed downstream on the output side 9 Frequency division device 10 signal splitter 11 Frequency divider 12 Amplitude Detector 13 Modulator 14 Frequency Multiplier 15 Receiving converter 16 Output Converter 17 Local Oscillator 18 Low-pass filter S RX Received signal f RX Receiving frequency B Bandwidth of the received signal S' RX Received signal S RX The received signal derived from S TX Output Signal S sim Simulated reflected signal S' sim Derived simulated reflected signal S1, S2: first partial received signal, second partial received signal A Amplitude information S 1f Frequency division received signal without amplitude information S fA Frequency division received signal with superimposed modulated amplitude information 1 / x frequency divider division factor y is the multiplication factor of the frequency multiplier
Claims
1. An inspection device (1) for testing a distance sensor (2) that operates using electromagnetic waves, The inspection device (1) has a predetermined receiving frequency (f ＲＸ ) and a received signal (S) having a predetermined signal bandwidth (B) ＲＸ A receiving element (3) that receives free-space electromagnetic waves as ) and an electromagnetic output signal (S ＴＸ The system comprises a radiating element (4) that emits ) and During the simulation, the received signal (S ＲＸ ) or the received signal (S ＲＸ The received signal (S') derived from ) ＲＸ ) is converted into a sampled signal by an analog / digital converter (5), the sampled signal is time-delayed into a time-delayed sampled signal by a signal processing unit (6), and the time-delayed sampled signal is simulated as a reflected signal (S) by a digital / analog converter (7). ｓｉｍ ) is converted to, The simulated reflection signal (S ｓｉｍ ), or the simulated reflection signal (S ｓｉｍ ) -derived simulated reflection signal (S' ｓｉｍ ), in an inspection device (1) that is radiated as an output signal (S ＴＸ ) through the radiation element (4). The received signal (S ＲＸ ) is divided by the signal splitter (10) into a first partial received signal (S １ ) and the second partial received signal (S ２ ) is divided into and at least the second partial received signal (S ２ ) is the received signal (S ＲＸ It has amplitude information (A) of ) The first partial received signal (S １ ) is then processed by the frequency divider (11) to obtain the received signal (S ＲＸ A frequency division receiving signal (S) no longer has amplitude information (A) of ) １ｆ ) is converted to, The second partial received signal (S ２ ) From the amplitude detector (12), the received signal (S ＲＸ The amplitude information (A) of ) is obtained, The modulator (13) receives a frequency division receiving signal (S) without amplitude information. １ｆ ) to the second partial received signal (S ２ The amplitude information (A) obtained from ) is superimposed and modulated, thereby the received signal (S ＲＸ The received signal (S') derived from ) ＲＸ By forming the received signal (S ＲＸ Frequency division received signal (S) having amplitude information (A) of ) ｆＡ ) is formed, The simulated reflected signal (S ｓｉｍ ) is then converted by the frequency multiplier (14) to the simulated reflected signal (S ｓｉｍ The signal (S') derived from ) ｓｉｍ It is characterized by being converted to ), Inspection device (1).
2. The signal divider (10) is implemented as a resistive power divider. The inspection apparatus (1) according to claim 1.
3. The frequency divider (11) is implemented using digital technology, particularly based on bistable flip-flops. The inspection apparatus (1) according to claim 1.
4. The amplitude detector (12) is implemented by a rectifier and a low-pass filter connected afterwards, particularly by a diode as the rectifier. The inspection apparatus (1) according to claim 1.
5. The frequency division received signal (S １ｆ The frequency divider (11) has a frequency divider coefficient (1 / x) selected such that the minimum frequency of the signal is greater than or equal to half of the signal bandwidth (B). The inspection apparatus (1) according to claim 1.
6. The low-pass filter (18) receives the frequency division received signal (S) having the amplitude information. ｆＡ ) is filtered, thereby the frequency division received signal (S ｆＡ The fundamental harmonic of the ) is the derived received signal (S' ＲＸ ) obtained as The inspection apparatus (1) according to claim 1.
7. The cutoff frequency of the low-pass filter (18) is the frequency division receiving signal (S １ｆ , S ｆＡ ) is between two and three times the minimum frequency, The inspection apparatus (1) according to claim 6.
8. The multiplication coefficient (y) of the frequency multiplier (14) corresponds to the reciprocal (1 / x) of the frequency division coefficient of the frequency divider (11). The inspection apparatus (1) according to claim 1.
9. The frequency multiplier (14) is implemented using semiconductor components with nonlinear transmission characteristics, particularly diodes or transistors, to form harmonics. The inspection apparatus (1) according to claim 1.
10. The received signal (S ＲＸ ) is frequency-shifted to a lower frequency by the receiving converter (15), The output signal of the frequency multiplier (14) is shifted to a higher frequency by the output converter (16). In particular, the absolute values of each frequency shift are equal. The inspection apparatus (1) according to claim 1.
11. In a frequency division device (9) for an inspection device (1) according to any one of claims 1 to 10, Received signal (S ＲＸ ) is divided by the signal divider (10) into a first partial received signal (S １ ) and the second partial received signal (S ２ ) is divided into and at least the second partial received signal (S ２ ) is the received signal (S ＲＸ It has amplitude information (A) of ) The first partial received signal (S １ ) is then processed by the frequency divider (11) to obtain the received signal (S ＲＸ A frequency division receiving signal (S) no longer has amplitude information (A) of ) １ｆ ) is converted to, The second partial received signal (S ２ ) From the amplitude detector (12), the received signal (S ＲＸ The amplitude information (A) of ) is obtained, The modulator (13) generates a frequency division received signal (S) without amplitude information (A). １ｆ ) to the second partial received signal (S ２ The amplitude information (A) obtained from ) is superimposed and modulated, thereby the received signal (S ＲＸ The received signal (S') derived from ) ＲＸ By forming the received signal (S ＲＸ Frequency division received signal (S) having amplitude information (A) of ) ｆＡ ) is characterized by the formation of Frequency division device (9).