JP2018031655A - Simulation target generation device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology for performing processing that simulates Doppler shift while relaxing a limitation caused by a sampling frequency.SOLUTION: A simulation target generation device comprises: a first mixer which generates an IF input signal by performing down conversion upon an RF input signal; an A/D converter for generating input waveform data by performing A/D conversion upon the IF input signal; a signal processor which generates waveform compression/decompression data by performing processing that compresses or decompresses a waveform in a time base direction, upon the input waveform data; a frequency shift processing part which generates frequency shifted waveform data by performing digital processing that shifts a frequency in accordance with a speed of an object reflecting radar waves and a frequency of a local oscillation signal, upon the waveform compression/decompression data; a D/A converter which generates an IF output signal by performing D/A conversion upon the frequency shifted waveform data; and a second mixer which generates an RF output signal by performing up conversion upon the IF output signal.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a simulation target generation apparatus and method.

  An apparatus that generates an RF (radio frequency) signal that simulates a reflected wave that is generated when a flying radar wave is reflected by an object is preferably used for testing a radar apparatus or generating an interfering radio wave. In this specification, such a device is referred to as a simulated target generator.

  The most typical configuration when an RF input signal is used as the simulation target generator is a configuration using a digital radio frequency memory (DRFM). The DRFM is a device configured to perform high-speed A / D conversion on a received radar wave, acquire waveform data representing the waveform of the radar wave, and store the waveform data in a memory. If desired digital processing is performed on the waveform data stored in the memory and D / A conversion is performed on the digital data obtained by the digital processing, a target RF signal can be obtained.

  One of the important digital processes performed in the DRFM is a process for simulating a frequency transition due to the Doppler effect, that is, a Doppler shift. When a radar wave is reflected by an object having a velocity, the frequency of the reflected wave deviates from the original radar wave frequency due to the Doppler effect. In order to appropriately simulate the reflected wave, it is desirable to generate an RF signal that simulates such a Doppler shift.

The following two methods are known as methods for simulating the Doppler shift.
The first method is a method using FFT (Fast Fourier Transform). The Doppler shift can be simulated by performing an FFT on the RF input signal corresponding to the radar wave coming in, performing an operation for shifting the frequency in the frequency domain, and further performing an inverse FFT. Such a technique is disclosed in, for example, Japanese Patent No. 3690332.

  However, since FFT and inverse FFT are block processes performed in units of blocks composed of waveform data for a fixed time, the method using FFT causes a problem of time delay.

  As a technique that does not cause the problem of time delay, for example, as disclosed in Japanese Patent No. 3242588, the waveform data obtained by high-speed A / D conversion is compressed or expanded in the time axis direction. A technique for performing the processing is known. In this publication, the signal included in the waveform data is thinned out, and the waveform is compressed in the time axis direction, and one sampling signal is increased to two sampling points. It discloses that the waveform is extended in the time axis direction by shifting the signal backward in the time axis.

  However, in such a method, the width of the Doppler shift that can be simulated is limited by the sampling frequency of the A / D conversion. Therefore, when simulating the Doppler shift of the reflected wave reflected by an object moving at high speed, the Doppler shift may not be simulated properly depending on the process of compressing the waveform shown in the waveform data in the time axis direction. obtain.

  Therefore, it is technically useful if a technique for performing a process of simulating a Doppler shift without being restricted by the sampling frequency is provided.

Patent No. 3690332 Japanese Patent No. 3224287

  Therefore, an object of the present invention is to provide a technique for relaxing the restriction due to the sampling frequency in the process of simulating the Doppler shift.

  The means for solving the problem will be described below with reference to the reference numerals used in the “DETAILED DESCRIPTION”. These symbols are added to show an example of the correspondence relationship between the description of “Claims” and “Mode for Carrying Out the Invention”.

  In one aspect of the present invention, the simulated target generator (10, 10C, 10D) performs down conversion on the RF input signal (21) corresponding to the radar wave using the local oscillation signal (22) to perform IF conversion. A first mixer (1) that generates an input signal (23), an A / D converter (12) that performs A / D conversion on the IF input signal (23) to generate input waveform data, and input waveform data Alternatively, a signal processor that generates waveform compression / expansion data by performing a process of compressing or expanding the waveform in the time axis direction on the waveform data obtained by performing a predetermined digital operation on the input waveform data. 14, 14C, 14D), digital processing for shifting the frequency according to the velocity of the object reflecting the radar wave and the frequency of the local oscillation signal (22) is performed on the waveform compression / decompression data. A frequency shift processing unit (15, 16) for generating waveform data after frequency shift, and D / A conversion for the waveform data after frequency shift or data obtained from the frequency shift waveform data to perform IF output signal (24 ) And a second mixer (3) that generates an RF output signal (25) by performing up-conversion on the IF output signal (24) using the local oscillation signal (22). ).

In a preferred embodiment, the velocity of the object is V, the frequency of the local oscillation signal (22) is f _L , the speed of light is c, and the frequency shift processing unit (15, 16) sets the frequency by 2V · f _L / c. A digital process for shifting is performed on the waveform compression / decompression data to generate waveform data after frequency shift.

  In one embodiment, the signal processor (14C) multiplies the input waveform data by the first to nth gains and delays the first to nth waveform data by the first to nth delay times, respectively. Generating (n is an integer of 2 or more), synthesizing the first to nth waveform data to generate synthesized waveform data, and performing a process of compressing or expanding the waveform in the time axis direction on the synthesized waveform data It is configured to generate waveform compression / decompression data.

  In another aspect of the present invention, the simulated target generator (10A) down-converts the RF input signal (21) corresponding to the radar wave using the first local oscillation signal (22) to perform the IF input signal. A first mixer (1) that generates (23), an A / D converter (12) that performs A / D conversion on the IF input signal (23) to generate input waveform data, and input waveform data, or A signal processor (14) for generating waveform compression / expansion data by performing processing for compressing or expanding the waveform in the time axis direction on the waveform data obtained by performing predetermined digital computation on the input waveform data A D / A converter (17) that performs D / A conversion on the waveform compression / decompression data to generate an IF output signal (24), a velocity of an object that reflects a radar wave, and a first local oscillation signal ( 22 A frequency shift processing unit (5, 6) for generating a second local oscillation signal (27) by shifting the frequency according to the frequency of the first local oscillation signal (22), and an IF output signal And a second mixer (3) for generating an RF output signal (25) by performing up-conversion with respect to (24) using the second local oscillation signal (27).

In a preferred embodiment, the velocity of the object is V, the frequency of the first local oscillation signal (22) is f _L , the speed of light is c, and the frequency shift processing unit (5, 6) is only 2V · f _L / c. A digital process for shifting the frequency is performed on the first local oscillation signal (22) to generate the second local oscillation signal (27).

  In still another aspect of the present invention, the simulated target generator (10B) performs down-conversion on the RF input signal (21) corresponding to the radar wave using the local oscillation signal (22) to perform the IF input signal ( 23), an A / D converter (12) that performs A / D conversion on the IF input signal (23) to generate input waveform data, and input waveform data, or A signal processor (14) for performing waveform compression / expansion processing on the waveform data obtained by performing predetermined digital computation on the input waveform data to generate waveform compression / expansion data; A D / A converter (17) for performing D / A conversion on the waveform compression / decompression data to generate an IF output signal (24), and a local oscillation signal (22) for the IF output signal (24). for A second mixer (3) that performs up-conversion to generate a first RF output signal (28), and a process of shifting the frequency according to the velocity of the object that reflects the radar wave and the frequency of the local oscillation signal (22) And a frequency shift processing unit (5, 7) for generating the second RF output signal (25) by performing the above operation on the first RF output signal (28).

In a preferred embodiment, the frequency shift processing unit (5, 7) sets the frequency by 2V · f _L / c, where V is the velocity of the object, f _{L is} the frequency of the local oscillation signal (22), and c is the speed of light. A digital process for shifting is performed on the first RF output signal (28) to generate a second RF output signal (25).

In still another aspect of the present invention, an RF output is used to simulate a reflected wave generated by reflecting a radar wave by first to n-th objects having first to _n- th velocities (V _{1 to} V _n ), respectively. A simulated target generator (10D) for generating a signal (25) is provided. The simulated target generator (10D) performs a down conversion on the RF input signal (21) corresponding to the radar wave using the local oscillation signal (22) to generate an IF input signal (23) ( 1), an A / D converter (12) that performs A / D conversion on the IF input signal (23) to generate input waveform data, and a signal processor (14D) that generates output waveform data from the input waveform data ), A D / A converter (17) that performs D / A conversion on the output waveform data to generate an IF output signal (24), and a local oscillation signal (22) for the IF output signal (24). And a second mixer (3) that performs upconversion to generate an RF output signal (25). The signal processor (14D) multiplies the input waveform data by the first to nth gains (n is an integer of 2 or more), respectively, and delays the first to nth delay times, respectively. First to nth variable gain delay devices (18 ₁ to 18 _n ) for generating n waveform data, and _first to _nth digital processing for simulating Doppler shift on the first to nth waveform data, respectively. And a Doppler shift processing unit (20 _{1 to} 20 _n ). Of the first to n-th Doppler shift processing units (20 _{1 to} 20 _n ), the i-th Doppler shift processing unit (20 _i ) (i is an integer of 1 to n) has a waveform with respect to the i-th waveform data. Is compressed or expanded in the time axis direction to generate i-th waveform compression / decompression data, and digital processing for shifting the frequency according to the i-th speed and the frequency of the local oscillation signal (22) is performed on the i-th waveform. It is configured to generate waveform data after the i-th frequency shift by performing the compression / decompression data. The signal processor (14D) supplies the synthesized waveform data obtained by synthesizing the first to nth frequency shifted waveform data to the D / A converter (17) as output waveform data.

In a preferred embodiment, assuming that the speed of the i-th object is Vi, the frequency of the local oscillation signal (22) is f _L , and the speed of light is c, the i-th Doppler shift processing unit (20 _i ) is 2V _i · f _L / Digital processing for shifting the frequency by c is performed on the i-th waveform compression / decompression data to generate waveform data after the i-th frequency shift.

  In still another aspect of the present invention, the simulation target generation method performs down-conversion on the RF input signal (21) corresponding to the radar wave using the local oscillation signal (22) to generate the IF input signal (23). A step of generating, a step of performing A / D conversion on the IF input signal (23) to generate input waveform data, and a predetermined digital operation on the input waveform data or the input waveform data. Processing for compressing or expanding the waveform in the time axis direction to generate waveform compression / expansion data, the velocity of the object reflecting the radar wave, and the frequency of the local oscillation signal (22). Digitally shifting the frequency in accordance with the waveform compression / decompression data to generate frequency-shifted waveform data; Or D / A conversion is performed on the data obtained from the waveform data or the waveform data after the frequency shift, and the IF output signal (24) is generated, and the local oscillation signal (22) is used for the IF output signal (24). And performing an up-conversion to generate an RF output signal (25).

  In still another aspect of the present invention, the simulation target generation method performs down-conversion on the RF input signal (21) corresponding to the radar wave using the first local oscillation signal (22) to perform the IF input signal (23 ), A step of performing A / D conversion on the IF input signal (23) to generate input waveform data, and a predetermined digital operation on the input waveform data or input waveform data. The waveform data obtained in this manner is subjected to processing for compressing or expanding the waveform in the time axis direction to generate waveform compression / decompression data, and D / A conversion is performed on the waveform compression / decompression data to perform IF The step of generating the output signal (24), the process of shifting the frequency according to the speed of the object reflecting the radar wave and the frequency of the first local oscillation signal (22) The step of generating the second local oscillation signal (27) with respect to the oscillation signal (22) and the up conversion using the second local oscillation signal (27) with respect to the IF output signal (24) Generating an output signal (25).

  In still another aspect of the present invention, the simulation target generation method performs down-conversion on the RF input signal (21) corresponding to the radar wave using the local oscillation signal (22) to generate the IF input signal (23). A step of generating, a step of performing A / D conversion on the IF input signal (23) to generate input waveform data, and a predetermined digital operation on the input waveform data or the input waveform data. The waveform data is compressed or expanded in the time axis direction to generate waveform compression / decompression data, and the waveform compression / decompression data is D / A converted to an IF output signal. Generating the first RF output signal (28) by generating the step (24) and performing up-conversion on the IF output signal (24) using the local oscillation signal (22). And a process of shifting the frequency according to the velocity of the object reflecting the radar wave and the frequency of the local oscillation signal (22) on the first RF output signal (28). Generating.

  ADVANTAGE OF THE INVENTION According to this invention, the technique which performs the process which simulates a Doppler shift, relaxing the restriction | limiting by a sampling frequency is provided.

It is a block diagram which shows the structure of the simulation target generator in 1st Embodiment. It is a graph which shows the process which expands a waveform in a time-axis direction. It is a graph which shows the process which compresses a waveform in a time-axis direction. It is a conceptual diagram which shows the simulation of the Doppler shift performed in the simulation target generator of 1st Embodiment. It is a block diagram which shows the structure of the simulation target generator in 2nd Embodiment. It is a block diagram which shows the structure of the simulation target generator in 3rd Embodiment. It is a block diagram which shows the structure of the simulation target generator in 4th Embodiment. It is a graph which shows notionally the input waveform and synthetic waveform in a 4th embodiment. It is a block diagram which shows the structure of the simulation target generator in 5th Embodiment.

  Hereinafter, embodiments will be described with reference to the accompanying drawings. In the following description, the same or corresponding components may be referred to by the same or corresponding reference numerals. In addition, when there are a plurality of components having the same configuration, they may be distinguished by adding a suffix to the reference symbol.

(First embodiment)
FIG. 1 is a block diagram showing the configuration of the simulated target generator 10 in the first embodiment. In the present embodiment, the simulated target generator 10 includes a mixer 1, a DRFM 2, a mixer 3, and a local oscillator 4. Oscillation frequency of the local oscillator 4 is _{f L.}

  The mixer 1 receives an RF input signal 21 corresponding to a radar wave. For example, a signal obtained by receiving a radar wave with an antenna is input to the mixer 1 as the RF input signal 21.

The mixer 1 down-converts the RF input signal 21 using the local oscillation signal 22 having the oscillation frequency f _L received from the local oscillator 4 to generate an IF (intermediate frequency) input signal 23. The oscillation frequency f _L of the local oscillator 4 is set so that the frequency band component of the RF input signal 21 shifts to a frequency band that can be processed by the DRFM 2 in the IF input signal 23 by down-conversion.

  The DRFM 2 is configured to process the IF input signal 23 generated by the down-conversion in the mixer 1 and generate an IF simulation signal 24 including waveform information simulating the reflected wave reflected by the object from the radar wave. Yes. As will be described later, in the present embodiment, the DRFM 2 is configured to generate an IF simulation signal 24 that simulates a Doppler shift.

  The mixer 3 upconverts the IF simulation signal 24 output from the DRFM 2 using the local oscillation signal 22 received from the local oscillator 4 to generate an RF output signal 25. The output RF output signal 25 may be used, for example, for evaluation of the radar device, or may be amplified and transmitted toward the direction in which the radar wave is flying by the antenna device.

  The DRFM 2 includes a filter 11, an A / D converter 12, a memory 13, a signal processor 14, a sine wave generator 15, a digital mixer 16, and a D / A converter 17.

  The filter 11 is configured to receive the IF input signal 23 from the mixer 1 and remove an alias component included in the IF input signal 23. For example, a low-pass filter may be used as the filter 11.

  The A / D converter 12 performs A / D conversion on the IF signal output from the filter 11 to generate waveform data.

  The memory 13 receives and stores the waveform data generated by the A / D converter 12. In addition, the memory 13 is also used as a work area for digital processing by the signal processor 14.

  The signal processor 14 performs digital processing on the waveform data stored in the memory 13. In the present embodiment, the signal processor 14 performs digital processing for compressing or expanding the waveform in the time axis direction. Hereinafter, data obtained by digital processing that compresses or expands a waveform in the time axis direction is hereinafter referred to as waveform compression / expansion data. The waveform compression / decompression data generated by the signal processor 14 is stored in the memory 13.

  FIG. 2A illustrates digital processing for expanding the waveform in the time axis direction, and FIG. 2B illustrates digital processing for compressing the waveform in the time axis direction. 2A and 2B, the broken line indicates the original waveform (the waveform indicated by the waveform data output from the A / D converter 12), and the solid line indicates the waveform indicated by the waveform compression / expansion data. Is shown. The process of compressing the waveform in the time axis direction corresponds to the process of shifting the frequency so that the frequency becomes higher, and the process of extending the waveform in the time axis direction is the process of shifting the frequency so that the frequency becomes lower. It corresponds to. According to such processing, it is possible to simulate a Doppler shift that occurs in accordance with the velocity of an object that reflects a radar wave.

For example, when the waveform data sampled at time t _i by the A / D converter 12 is Q (t _i ) (i = 1, 2, 3,...), The time series data Q (A · (t _i −t _DL )) is delayed by t _{DL in the} time axis direction, and the waveform is compressed A times in the time axis direction when A> 1, and the waveform is 1 / A when A <1. The data is expanded twice. The waveform data Q ^ (t _k ) (k = 1, 2, 3,...) Obtained by compressing or expanding the waveform in the time axis direction is interpolated from the time series data Q (A · (t _i −t _DL )). It can ask for. In one embodiment, the time series data Q ^ (t _k ) calculated in this way may be used as waveform compression / decompression data.

It should be noted that the maximum shift amount of the frequency is limited by the sampling frequency when the original waveform data is acquired by the A / D converter 12. For example, when the frequency of the original radar wave is f and the velocity of the object reflecting the radar wave is V, the amount of frequency shift due to the Doppler shift should be approximately 2 V · f / c. . Here, c is the speed of light. On the other hand, the frequency of the IF input signal 23 input to the A / D converter 12 is f ₀ (= f−f _L ) obtained by subtracting the frequency f _L of the local oscillation signal 22 from the frequency f, and the IF of the frequency f ₀ When the sampling frequency fs of the A / D converter 12 is set so that the input signal 23 can be sampled (for example _, when the sampling frequency fs of _the A / D converter 12 is set to 2f ₀ ), a realizable frequency shift The amount is 2V · f ₀ / c. Therefore, in the process of compressing the waveform in the time axis direction, it may be difficult to shift the frequency by 2 V · f / c.

In order to cope with such a problem, in this embodiment, a sine wave generator 15 and a digital mixer 16 are provided. The sine wave generator 15 and the digital mixer 16 perform digital processing for shifting the frequency on the waveform compression / decompression data based on the velocity V of the object that reflects the radar wave and the frequency f _L of the local oscillation signal 22. It operates as a frequency shift processing unit.

Specifically, the sine wave generator 15 generates a sine wave digital value that changes in a sine wave _shape at a frequency f _DP . Here, the frequency f _DP is defined by the following equation (1): f _DP = 2V · f _L / c (1)
Here, V is the velocity of the object that reflects the radar wave, f _L is the frequency of the local oscillation signal 22, and c is the speed of light.

The digital mixer 16 uses the sine wave digital value received from the sine wave generator 15 to receive the digital processing for shifting the frequency by f _DP (= 2V · f _L / c) from the memory 13. To do. Hereinafter, the waveform data output from the digital mixer 16 may be referred to as waveform data after frequency shift. The frequency-shifted waveform data output from the digital mixer 16 represents a waveform obtained by further shifting the frequency component of the waveform compression / expansion data by the frequency f _DP . For example, the digital mixer 16 calculates the product of the waveform compression / decompression data received from the memory 13 and the sine wave digital value received from the sine wave generator 15, and further performs digital filtering to remove alias components. It may be configured.

  The D / A converter 17 performs D / A conversion on the frequency-shifted waveform data output from the digital mixer 16 to generate an IF simulation signal 24. As described above, the IF simulation signal 24 includes waveform information simulating a reflected wave of a radar wave reflected by an object, and the IF simulation signal 24 is up-converted by the mixer 3 to be finally obtained. An RF output signal 25 to be output is generated.

  In an actual implementation of DRFM2, the signal processor 14, the sine wave generator 15, and the digital mixer 16 included in the DRFM2 may be monolithically integrated in an application specific integrated circuit (ASIC). In this case, the frequency-shifted waveform data supplied to the D / A converter 17 is generated by the ASIC and the memory 13.

The simulation target generator 10 of the present embodiment appropriately simulates the Doppler shift generated in the reflected wave by providing the DRFM 2 with the sine wave generator 15 and the digital mixer 16 in addition to the signal processor 14. An RF output signal 25 can be generated. FIG. 3 is a conceptual diagram showing simulation of Doppler shift performed in the simulated target generator 10 of the present embodiment. When the velocity of the object reflecting the radar wave is V and the frequency of the radar wave is f, a frequency shift of 2V · f / c may be generated in the DRFM2 in order to appropriately simulate the Doppler shift. desirable. The simulated target generator 10 of the present embodiment generates a frequency shift of 2V · f ₀ / c by the signal processor 14 and a frequency shift of 2V · f _L / c by the digital mixer 16 as a whole. Generates a frequency shift of 2 V · f / c and can appropriately simulate a Doppler shift. Note that f _L is the frequency of the local oscillation signal 22, and f ₀ is f−f _L.

The simulated target generator 10 of the present embodiment is also useful when generating the RF output signal 25 that appropriately simulates the Doppler shift generated in the reflected wave when the original frequency f of the radar wave is unknown. is there. When the frequency f of the original radar wave is unknown, the frequency shift 2V · f / c to be generated is not determined. However, in the simulated target generator 10 of the present embodiment, the digital mixer 16 can generate a frequency shift of 2 V · f _L / c, so that the adjustment range can be adjusted even when the frequency shift is adjusted by adjustment by the signal processor 14. Can be small.

(Second Embodiment)
FIG. 4 is a block diagram showing the configuration of the simulated target generator 10A in the second embodiment of the present invention. The simulated target generator 10A of the second embodiment has a configuration similar to the simulated target generator 10 of the first embodiment shown in FIG. However, the configuration of the simulated target generator 10A of the second embodiment is different from the simulated target generator 10 of the first embodiment in the following points.

  First, the DRFM 2A does not include the sine wave generator 15 and the digital mixer 16. In this embodiment, the waveform compression / decompression data generated by the signal processor 14 is supplied to the D / A converter 17 as it is, and the IF simulation signal 24 performs D / A conversion on the waveform compression / decompression data. Is generated. As described above, the waveform compression / decompression data generated by the signal processor 14 is data obtained by digital processing that compresses or expands the waveform in the time axis direction.

Furthermore, the simulated target generator 10A additionally includes a local oscillator 5 and a mixer 6. The local oscillator 5 generates a local oscillation signal 26 having a frequency f _DP (= 2V · f _L / c). Here, V is the speed of the object from which the radar wave is reflected, f _L is the frequency of the local oscillation signal 22, and c is the speed of light. The mixer 6 generates a local oscillation signal 27 having a frequency f _L + f _DP or f _L −f _DP from the local oscillation signal 22 supplied from the local oscillator 4 and the local oscillation signal 26 supplied from the local oscillator 5. When simulating a Doppler shift in which the frequency increases, the mixer 6 generates a local oscillation signal 27 having a frequency f _L + f _DP . Conversely, when simulating a Doppler shift in which the frequency decreases, the mixer 6 generates a local oscillation signal 27 having a frequency f _L −f _DP . The mixer 3 upconverts the IF simulation signal 24 output from the DRFM 2 using the local oscillation signal 27 received from the mixer 6 to generate an RF output signal 25.

Similarly to the simulated target generator 10 of the first embodiment, the simulated target generator 10A of the second embodiment can generate the RF output signal 25 that appropriately simulates the Doppler shift generated in the reflected wave. Also in this embodiment, the signal processor 14 can generate a frequency shift of 2V · f ₀ / c. In addition, in the present embodiment, the mixer 3 performs up-conversion on the IF simulation signal 24 using the local oscillation signal 27 of the frequency f _L + f _DP or f _L −f _DP , so that f _DP ( = 2V · f _L / c). Therefore, the simulated target generator 10A of the present embodiment can generate a frequency shift of 2 V · f / c as a whole and appropriately simulate the Doppler shift.

(Third embodiment)
FIG. 5 is a block diagram showing the configuration of the simulated target generator 10B in the third embodiment. The simulated target generator 10B of the third embodiment has a configuration similar to the simulated target generator 10A of the second embodiment shown in FIG. However, the configuration of the simulated target generator 10B of the third embodiment is different from the simulated target generator 10B of the second embodiment in the following points.

  Also in the third embodiment, the DRFM 2B does not include the sine wave generator 15 and the digital mixer 16. In this embodiment, the waveform compression / decompression data generated by the signal processor 14 is supplied to the D / A converter 17 as it is, and the IF simulation signal 24 performs D / A conversion on the waveform compression / decompression data. Is generated. As described above, the waveform compression / decompression data generated by the signal processor 14 is data obtained by digital processing that compresses or expands the waveform in the time axis direction.

  Further, the mixer 3 performs up-conversion on the IF simulation signal 24 output from the DRFM 2B using the local oscillation signal 22 received from the local oscillator 4, and generates an RF output signal 28.

However, in the third embodiment, since the frequency shift of f _DP (= 2V · f _L / c) is additionally generated, the simulated target generator 10B additionally adds the local oscillator 5 and the mixer 7. I have. The local oscillator 5 generates a local oscillation signal 26 having a frequency f _DP (= 2V · f _L / c). Here, V is the speed of the object from which the radar wave is reflected, f _L is the frequency of the local oscillation signal 22, and c is the speed of light. The mixer 7 uses the local oscillation signal 26 received from the local oscillator 5 to perform a frequency shift for shifting the frequency by f _DP to the RF output signal 28 to generate an RF output signal 25 to be finally output. . When simulating a Doppler shift in which the frequency is increased, the mixer 7 performs a frequency shift to increase the frequency by f _DP and generates the RF output signal 25. On the other hand, when simulating a Doppler shift in which the frequency decreases, the mixer 7 performs a frequency shift that lowers the frequency by f _DP to generate the RF output signal 25.

Similar to the simulated target generators 10 and 10A of the first and second embodiments, the simulated target generator 10B of the third embodiment also generates the RF output signal 25 that appropriately simulates the Doppler shift that occurs in the reflected wave. can do. Also in this embodiment, the signal processor 14 can generate a frequency shift of 2V · f ₀ / c. In addition, in the present embodiment, the mixer 7 can generate a frequency shift of the frequency f _DP (= 2V · f _L / c). Therefore, the simulated target generator 10 of the present embodiment can generate a frequency shift of 2 V · f / c as a whole and appropriately simulate the Doppler shift.

(Fourth embodiment)
FIG. 6 is a block diagram showing the configuration of the simulated target generator 10C in the fourth embodiment. The simulated target generator 10C of the fourth embodiment has a configuration similar to the simulated target generator 10 of the first embodiment shown in FIG. However, in the simulated target generator 10C of the fourth embodiment, the signal processor 14C can execute digital processing for generating a complex waveform in addition to digital processing for compressing or expanding the waveform in the time axis direction. It is configured.

Specifically, in this embodiment, the signal processor 14 _< / b _> C includes variable gain delay units 18 ₁ to 18 _n and a waveform compression / decompression processor 19.

A delay time and a gain can be set for each of the variable gain delay devices 18 ₁ to 18 _n . Hereinafter, the delay time set in the gain variable delay device 18 _i is described as Ti, and the gain as Ai (where i is an integer of 1 to n). Each gain variable delay device 18 _i performs multiplication by multiplying the waveform data (waveform data generated by the A / D converter 12) stored in the memory 13 by the gain Ai, and delays by the delay time Ti. Output. Combined waveform data obtained by combining the data output from each of the variable gain delay devices 18 ₁ to 18 _n (that is, data of the sum of the data output from each of the variable gain delay devices 18 ₁ to 18 _n ). Is input to the waveform compression / decompression processor 19.

FIG. 7 shows combined waveform data obtained by combining the waveform (input waveform) shown in the waveform data stored in the memory 13 and the data output from each of the variable gain delay devices 18 ₁ to 18 _n. The waveform (synthetic waveform) shown in FIG. When the RF input signal 21 corresponding to the radar wave has a pulse waveform, the waveform shown in the waveform data is also a pulse waveform. On the other hand, the waveform shown in the combined waveform data has a complex waveform in which a plurality of pulse waveforms are superimposed.

Returning to FIG. 6, the waveform compression / decompression processor 19 compresses the waveform in the time axis direction with respect to the combined waveform data obtained by synthesizing the data output from each of the variable gain delay units 18 ₁ to 18 _n , or Waveform compression / decompression data is generated by performing digital processing for decompression. The waveform compression / decompression data generated by the waveform compression / decompression processor 19 is input to the digital mixer 16.

The digital mixer 16 digitally shifts the frequency using the sine wave digital value received from the sine wave generator 15 with respect to the waveform compression / decompression data generated by the waveform compression / decompression processor 19 of the signal processor 14C. To generate waveform data after frequency shift. The frequency-shifted waveform data output from the digital mixer 16 represents a waveform obtained by further shifting the frequency component of the waveform compression / expansion data by the frequency f _DP (= 2V · f _L / c). For example, the digital mixer 16 calculates the product of the waveform compression / decompression data received from the memory 13 and the sine wave digital value received from the sine wave generator 15, and further performs digital filtering to remove alias components. It may be configured.

  The D / A converter 17 performs D / A conversion on the frequency-shifted waveform data output from the digital mixer 16 to generate an IF simulation signal 24. The IF simulation signal 24 is up-converted by the mixer 3 to generate an RF output signal 25 to be finally output.

Similarly to the simulated target generators 10, 10 </ b> A, and 10 </ b> B of the first to third embodiments, the simulated target generator 10 </ b> C of the fourth embodiment also properly simulates the Doppler shift that occurs in the reflected wave. Can be generated. Specifically, also in this embodiment, the waveform compression / decompression processor 19 of the signal processor 14C can generate a frequency shift of 2V · f ₀ / c, and a frequency shift of 2V · f _L / c. Can be generated by the digital mixer 16. Therefore, the simulation target generator 10C of the present embodiment generates a frequency shift of 2V · f / c as a whole, and can appropriately simulate the Doppler shift.

In addition, in this embodiment, by providing the variable gain delay devices 18 ₁ to 18 _n, it is possible to generate the RF output signal 25 having a complicated waveform. This is suitable for simulating a reflected wave when the radar wave is complicatedly reflected by an object.

  The signal processor 14C used in the simulated target generator 10C of the fourth embodiment is a simulated target generator 10A (see FIG. 4) of the second embodiment, and a simulated target generator 10B of the third embodiment. (See FIG. 5). When the signal processor 14C used in the fourth embodiment is applied to the simulated target generator 10A of the second embodiment or the simulated target generator 10B of the third embodiment, the signal processor 14C is generated by the signal processor 14C. The waveform compression / decompression data is input to the D / A converter 17.

(Fifth embodiment)
FIG. 8 is a block diagram illustrating a configuration of the simulated target generator 10D according to the fifth embodiment. The simulated target generator 10D of the fifth embodiment has a configuration similar to the simulated target generator 10 of the first embodiment shown in FIG. However, in the simulated target generator 10D of the fifth embodiment, the digital processing performed by the signal processor 14D is changed.

Specifically, in the fifth embodiment, the signal processor 14D includes variable gain delay devices 18 ₁ to 18 _n and Doppler shift processing units 20 _{1 to} 20 _n .

A delay time and a gain can be set for each of the variable gain delay devices 18 ₁ to 18 _n . Hereinafter, the delay time set in the gain variable delay device 18 _i is described as Ti, and the gain as Ai (where i is an integer of 1 to n). Each gain variable delay device 18 _i performs multiplication by multiplying the waveform data (waveform data generated by the A / D converter 12) stored in the memory 13 by the gain Ai, and delays by the delay time Ti. Output.

The Doppler shift processing units 20 _{1 to} 20 _n perform digital processing for simulating Doppler shift on the data output from the variable gain delay units 18 ₁ to 18 _n , respectively. Speeds V1 to Vn of the objects # 1 to #n are set in the Doppler shift processing units 20 _{1 to} 20 _n , respectively. The Doppler shift processing unit 20 _i performs a calculation that simulates a Doppler shift caused by reflection by the object #i at the speed Vi.

Each Doppler shift processing unit 20 _i includes a waveform compression / decompression processor 31 _i , a sine wave generator 32 _i, and a digital mixer 33 _i .

The waveform compression / decompression processor 31 _i performs digital processing for compressing or expanding the waveform in the time axis direction on the data output from the variable gain delay unit 18 _i to generate waveform compression / decompression data. .

The sine wave generator 32 _i generates a sine wave digital value that changes sinusoidally at a frequency f _DPi . Here, the frequency f _DPi is defined by the following equation (2): f _DPi = 2V _i · f _L / c (2)
Here, V _i is the speed of the object #i that reflects the radar wave, f _L is the frequency of the local oscillation signal 22 generated by the local oscillator 4, and c is the speed of light.

The digital mixer 33 _i performs a frequency shift on the waveform compression / decompression data received from the waveform compression / decompression processor 31 _i by performing an operation to shift the frequency using the sine wave digital value received from the sine wave generator 15. After waveform data is generated. The frequency-shifted waveform data output from the digital mixer 33 _i represents a waveform obtained by further shifting the frequency component of the waveform compression / decompression data received from the waveform compression / decompression processor 31 _i by the frequency f _DPi .

The frequency-shifted waveform data output from each of the Doppler shift processing units 20 _{1 to} 20 _n is synthesized to generate synthesized waveform data. The generated combined waveform data is output from the signal processor 14D and stored in the memory 13.

  The combined waveform data output from the signal processor 14D and stored in the memory 13 is supplied to the D / A converter 17 as output waveform data indicating the waveform of the RF output signal 25. The D / A converter 17 performs D / A conversion on the output waveform data to generate an IF simulation signal 24. The IF simulation signal 24 is up-converted by the mixer 3 to generate an RF output signal 25 to be finally output.

In the simulated target generator 10D of the fifth embodiment, the combined waveform data generated by the variable gain delay devices 18 ₁ to 18 _n and the Doppler shift processing units 20 _{1 to} 20 _n connected in parallel is output as an RF output. Since it is used as output waveform data indicating the waveform of the signal 25, it is possible to appropriately simulate a complex reflected wave generated by reflection of a radar wave by many objects. At this time, the frequency shift of _2V i · _f 0 / c generated by the Doppler shift processor 20 _i waveform compression / decompression processing unit 31 _i of the sine wave generator 32 _i and the digital mixer 33 _i and by _2V i · f _Since a frequency shift of _L / c can be generated and a frequency shift of 2V _i · f / c can be generated as a whole of the Doppler shift processing unit 20 _i , the Doppler shift can be appropriately simulated.

  Although the embodiment of the present invention has been specifically described above, the present invention is not limited to the above embodiment. Those skilled in the art will appreciate that the invention may be practiced with various modifications.

10, 10A to 10D: Simulated target generator 1: Mixer 3: Mixer 4, 5: Local oscillator 6, 7: Mixer 11: Filter 12: A / D converter 13: Memory 14, 14C, 14D: Signal processor 15: Sine wave generator 16: Digital mixer 17: D / A converters 18 ₁ to 18 _n : Variable gain delay unit 19: Waveform compression / decompression processor 20 _{1 to} 20 _n : Doppler shift processing unit 21: RF input signal 22: Local Oscillation signal 23: IF input signal 24: IF simulation signal 25: RF output signal 26: Local oscillation signal 27: Local oscillation signal 28: RF output signals 31 _{1 to} 31 ₃ : Waveform compression / expansion processors 32 _{1 to} 32 ₃ : Sine wave generators 33 _{1 to} 33 ₃ : digital mixer

Claims (12)

A first mixer that generates an IF input signal by down-converting an RF input signal corresponding to a radar wave using a local oscillation signal;
An A / D converter that performs A / D conversion on the IF input signal to generate input waveform data;
Generate waveform compression / expansion data by compressing or expanding the waveform in the time axis direction for the input waveform data or the waveform data obtained by performing a predetermined digital operation on the input waveform data A signal processor to
A frequency shift processing unit that performs digital processing for shifting the frequency according to the velocity of the object that reflects the radar wave and the frequency of the local oscillation signal on the waveform compression / decompression data to generate waveform data after frequency shift When,
A D / A converter that performs D / A conversion on the waveform data after frequency shift or data obtained from the frequency shift waveform data to generate an IF output signal;
A simulation target generator comprising: a second mixer that generates an RF output signal by performing up-conversion on the IF output signal using the local oscillation signal. The simulated target generator according to claim 1,
The speed of the object is V, the frequency of the local oscillation signal is f _L , and the speed of light is c.
The frequency shift processing unit is configured to perform digital processing for shifting the frequency by 2V · f _L / c on the waveform compression / expansion data to generate the waveform data after the frequency shift. . The simulation target generator according to claim 1 or 2,
The signal processor multiplies the input waveform data by first to n-th gains and generates first to n-th waveform data by delaying them by first to n-th delay times, respectively (n is 2), the first to n-th waveform data is synthesized to generate synthesized waveform data, and the waveform compression / decompression is performed on the synthesized waveform data by compressing or expanding the waveform in the time axis direction. A simulated target generator configured to generate decompressed data. A first mixer that generates an IF input signal by down-converting an RF input signal corresponding to a radar wave using a first local oscillation signal;
An A / D converter that performs A / D conversion on the IF input signal to generate input waveform data;
Generate waveform compression / expansion data by compressing or expanding the waveform in the time axis direction for the input waveform data or the waveform data obtained by performing a predetermined digital operation on the input waveform data A signal processor to
A D / A converter that performs D / A conversion on the waveform compression / decompression data to generate an IF output signal;
Frequency shift processing for generating a second local oscillation signal by performing a process for shifting the frequency according to the velocity of the object reflecting the radar wave and the frequency of the first local oscillation signal on the first local oscillation signal And
And a second mixer for generating an RF output signal by performing up-conversion on the IF output signal using the second local oscillation signal. The simulation target generator according to claim 4,
V is the velocity of the object, f _{L is} the frequency of the first local oscillation signal, and c is the speed of light.
The frequency shift processing unit is configured to generate the second local oscillation signal by performing digital processing for shifting the frequency by 2V · f _L / c on the first local oscillation signal. . A first mixer that generates an IF input signal by down-converting an RF input signal corresponding to a radar wave using a local oscillation signal;
An A / D converter that performs A / D conversion on the IF input signal to generate input waveform data;
Generate waveform compression / expansion data by compressing or expanding the waveform in the time axis direction for the input waveform data or the waveform data obtained by performing a predetermined digital operation on the input waveform data A signal processor to
A D / A converter that performs D / A conversion on the waveform compression / decompression data to generate an IF output signal;
A second mixer that upconverts the IF output signal using the local oscillation signal to generate a first RF output signal;
A frequency shift processing unit for performing a process of shifting the frequency according to the velocity of the object reflecting the radar wave and the frequency of the local oscillation signal on the first RF output signal to generate a second RF output signal; Simulated target generator. The simulation target generator according to claim 6,
The speed of the object is V, the frequency of the local oscillation signal is f _L , and the speed of light is c.
The simulation target generator configured to generate the second RF output signal by performing digital processing for shifting the frequency by 2V · f _L / c on the first RF output signal. A simulation target generator for generating an RF output signal so as to simulate a reflected wave generated by reflecting a radar wave by first to nth objects having first to nth velocities, respectively.
A first mixer that generates an IF input signal by down-converting an RF input signal corresponding to the radar wave using a local oscillation signal;
An A / D converter that performs A / D conversion on the IF input signal to generate input waveform data;
A signal processor for generating output waveform data from the input waveform data;
A D / A converter that performs an D / A conversion on the output waveform data to generate an IF output signal;
A second mixer for generating an RF output signal by performing up-conversion on the IF output signal using the local oscillation signal;
The signal processor is
First to n-th variable gain delay units for multiplying the input waveform data by first to n-th gains and generating first to n-th waveform data by delaying them by first to n-th delay times, respectively; (N is an integer of 2 or more),
First to n-th Doppler shift processing units for performing digital processing for simulating Doppler shift on the first to n-th waveform data,
An i-th Doppler shift processing unit (i is an integer of 1 to n) of the first to n-th Doppler shift processing units compresses or expands the waveform in the time axis direction with respect to the i-th waveform data. Processing is performed to generate i-th waveform compression / decompression data, and digital processing is performed on the i-th waveform compression / decompression data to shift the frequency according to the i-th speed and the frequency of the local oscillation signal. Configured to generate waveform data after the i-th frequency shift;
The said signal processor supplies the synthetic | combination waveform data obtained by synthesize | combining the waveform data after the said 1st thru | or nth frequency shift to the said D / A converter as said output waveform data Simulation target generator. The simulated target generator according to claim 8,
The speed of the i-th object is Vi, the frequency of the local oscillation signal is f _L , and the speed of light is c.
The i-th Doppler shift processing unit performs digital processing for shifting the frequency by 2V _i · f _L / c on the i-th waveform compression / decompression data to generate the waveform data after the i-th frequency shift. Configured simulation target generator. A step of down-converting an RF input signal corresponding to a radar wave using a local oscillation signal to generate an IF input signal;
Performing A / D conversion on the IF input signal to generate input waveform data;
Generate waveform compression / expansion data by compressing or expanding the waveform in the time axis direction for the input waveform data or the waveform data obtained by performing a predetermined digital operation on the input waveform data And steps to
Performing digital processing for shifting the frequency according to the velocity of the object reflecting the radar wave and the frequency of the local oscillation signal on the waveform compression / expansion data to generate waveform data after frequency shift;
Performing D / A conversion on the waveform data after frequency shift or data obtained from the frequency shift waveform data to generate an IF output signal;
And performing an up-conversion on the IF output signal using the local oscillation signal to generate an RF output signal. A step of down-converting an RF input signal corresponding to a radar wave using a first local oscillation signal to generate an IF input signal;
Performing A / D conversion on the IF input signal to generate input waveform data;
Generate waveform compression / expansion data by compressing or expanding the waveform in the time axis direction for the input waveform data or the waveform data obtained by performing a predetermined digital operation on the input waveform data And steps to
Performing D / A conversion on the waveform compression / decompression data to generate an IF output signal;
Performing a process of shifting the frequency according to the velocity of the object reflecting the radar wave and the frequency of the first local oscillation signal on the first local oscillation signal to generate a second local oscillation signal;
And performing an up-conversion on the IF output signal using the second local oscillation signal to generate an RF output signal. A step of down-converting an RF input signal corresponding to a radar wave using a local oscillation signal to generate an IF input signal;
Performing A / D conversion on the IF input signal to generate input waveform data;
Generate waveform compression / expansion data by compressing or expanding the waveform in the time axis direction for the input waveform data or the waveform data obtained by performing a predetermined digital operation on the input waveform data And steps to
Performing D / A conversion on the waveform compression / decompression data to generate an IF output signal;
Performing up-conversion on the IF output signal using the local oscillation signal to generate a first RF output signal;
Performing a process of shifting the frequency on the first RF output signal according to the velocity of the object reflecting the radar wave and the frequency of the local oscillation signal to generate a second RF output signal. Occurrence method.

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