JP2019100947A - Radar device and radar signal processing method of the same - Google Patents

Abstract

To secure LPI properties, and observe a speed and distance of a target.SOLUTION: A radar device of an embodiment is configured to: use a transmission wavefront having a plurality of pulse widths and a signal with a PRF synthesized, and conduct correlation processing of a signal extracted by a first PRF for each PRI, using a reference signal of a first modulation signal; extract a Doppler by FFT processing between the PRFs, using a result undergoing the correlation processing; conduct correlation processing of a signal extracted by a second PRF for each PRI with respect to a reception signal, using a reference signal of a second modulation signal; and by use of a result undergoing the correlation processing, conduct correlation processing to a third modulation signal between pulses with a signal corrected by the Doppler extracted in a first pulse string as the reference signal, using a signal string extracted for each range cell in the PRI and extract a range. Accordingly, in addition to a broad band SS modulation, it is made hard to extract a pulse width and the PRF, and range finding and velocimetry are enabled, as securing a high LPI property.SELECTED DRAWING: Figure 4

Description

  The present embodiment relates to a radar apparatus that calculates a target distance and speed, and a radar signal processing method thereof.

  As an LPI (Low Probability of Intercept) radar device that lowers detectability, there are one that performs SS (Spread Spectrum) modulation in the pulse, and one that performs coding for each pulse and performs range compression using a reference signal ( Patent Document 1).

  However, in recent years, it is expected that the performance of the radar wave receiving apparatus will be broadened, and it may be expected that sufficient LPI performance can not be ensured by SS modulation alone, and a method for securing further LPI performance is desired. In addition, when wide band transmission by SS modulation, the reception system also becomes wide band, so when applied to, for example, DBF (Digital Beam Forming) radar, the transfer capacity from the elements (sub array) becomes large, and the hardware There was an issue of increasing scale.

JP, 2014-182010, A

Coding radar, Yoshida, 'revised radar technology', The Institute of Electronics, Information and Communication Engineers, pp. 278-280 (1996) Code code (M series) generation method, M. I. Skolnik, 'Introduction to radar systems', pp. 429-430, McGRAW-HILL (1980) SS (Spread Spectrum) modulation, Marubayashi, 'Spread spectrum communication and its application', The Institute of Electronics, Information and Communication Engineers, ed., Pp. 1-18 (1998) Frequency hopping, valley, 'data communication and digital signal processing', Corona, p. 63-65 (1996) BPSK, QPSK, Nishimura, 'Communication system design by digital signal processing', CQ publisher, pp. 222-226 (2006) CFAR (Constant False Alarm Rate) processing, Yoshida, 'Revision radar technology', The Institute of Electronics, Information and Communication Engineers, pp. 87-89 (1996)

  As described above, in the radar apparatus adopting the coding method, there is a case where sufficient LPI property can not be secured only by performing SS modulation within or between pulses in order to improve LPI property. In addition, in the case of wide band transmission by SS modulation, the reception system also becomes wide band, so, for example, when applied to DBF radar, the transfer capacity from elements (sub-arrays) increases and the hardware scale increases. there were.

  The present embodiment has been made in view of the above problems, and an object of the present invention is to provide a radar apparatus capable of observing a target speed and distance while securing LPI characteristics, and a radar signal processing method thereof.

  In order to solve the above problems, according to the present embodiment, in a radar apparatus using modulation pulses by encoding or random signal (noise), a first pulse width for Doppler extraction, a first PRF (Pulse Repetition Frequency) The first pulse train, the second pulse width for ranging, and the second pulse train for the second PRF are combined, and in the first pulse train, the inside of the pulse is modulated with the first modulation signal, and in the second pulse train, different from the first pulse train A transmission signal that is intrapulse-modulated by the second modulation signal and further modulated by the third modulation signal of a random signal (noise) between pulses is transmitted from the transmission antenna, and the reception signal of the reception antenna is extracted by the first PRF The signal is subjected to correlation processing per PRI (fast-time axis) using the reference signal of the first modulation signal, and the correlation processing is performed using the first PRF and the second PRF (sl Doppler is extracted by FFT processing of ow-time axis). Next, with respect to the received signal of the receiving antenna, the signal extracted by the second PRF is subjected to correlation processing for each PRI (fast-time axis) using the reference signal of the second modulation signal, and the result of the correlation processing is used. A range is extracted by correlating the Doppler-corrected signal extracted by the first pulse train to the third modulated signal between pulses using the signal train extracted for each range cell in the PRI as a reference signal. That is, in addition to wideband SS modulation, it is difficult to extract pulse width and PRF by using a transmission waveform in which signals having a plurality of pulse widths and PRFs are combined, so it is possible to achieve high LPI performance while securing high LPI performance. Speed and distance can be observed.

FIG. 2 is a block diagram showing the configuration of a transmission system applied to the radar device according to the first embodiment. FIG. 2 is a block diagram showing the configuration of a reception system applied to the radar device according to the first embodiment. FIG. 5 is a timing waveform chart showing two types of pulse trains different in pulse width and PRF (Pulse Repetition Frequency) and a mixed waveform thereof in the first embodiment. FIG. 2 is a block diagram showing the configuration of a reception system of the radar device according to the first embodiment. FIG. 5 is a timing waveform chart showing how transmission signals of pulse trains P1 and P2 are generated from a chirp modulation signal in the first embodiment. FIG. 7 is a timing waveform chart showing a state in which pulse trains P1 and P2 are separated from the reception signal in the first embodiment, and FFT on the slow-time axis is performed for each range cell on the fast-time axis. FIG. 7 is a timing waveform chart showing how to improve the SN by adding a signal subjected to correlation processing for each frequency division as processing of the fast-time axis in the PRI of the pulse train P1 in the first embodiment. FIG. 7 is a timing waveform chart showing how an FFT is performed on a pulse train P1 in the first embodiment. FIG. 7 is a timing waveform chart showing how to improve the SN by adding the signal subjected to correlation processing for each division frequency as processing of the fast-time axis in the PRI of the pulse train P2 in the first embodiment. FIG. 7 is a timing waveform chart showing how correlation processing is performed only with the pulse train P2 in the first embodiment. The block diagram which shows the structure of the receiving system of the radar apparatus concerning 2nd Embodiment. FIG. 14 is a timing waveform chart showing how to improve the SN by adding the signals subjected to correlation processing in all frequency bands as processing of the fast-time axis in the PRI of the pulse train P1 in the second embodiment. FIG. 14 is a timing waveform chart showing how to improve the SN by adding the signals subjected to correlation processing in all frequency bands as processing of the fast-time axis in the PRI of the pulse train P2 in the second embodiment. The block diagram which shows the structure of the receiving system of the radar apparatus concerning 3rd Embodiment. The flowchart which shows the flow of a process which obtains the correlation output with respect to each Doppler using the reference signal correct | amended by different Doppler in 3rd Embodiment. In 3rd Embodiment, the conceptual diagram which shows the mode of the discrimination of a target for clutter.

  Hereinafter, embodiments will be described with reference to the drawings. In the description of each embodiment, the same parts will be denoted by the same reference numerals, and overlapping descriptions will be omitted.

First Embodiment
The radar apparatus according to the first embodiment will be described with reference to FIGS. 1 to 10.

  1 and 2 show configurations of a transmission system and a reception system applied to the radar apparatus according to the first embodiment, respectively, and FIG. 3 shows pulse widths and PRFs (Pulse Repetition Frequency) in the first embodiment. ) And two mixed pulse trains P1 and P2 and their mixed waveforms P1 + P2 are shown. Further, FIG. 4 shows the configuration of a receiving system adopted in the first embodiment, and FIG. 5 shows a state of generating a transmission signal.

  The transmission system shown in FIG. 1 includes transmission antenna 1, pulse modulator 2, frequency converter 3, modulator 4, reference signal generator 5, modulation signal generator 6, IFFT processor 7, frequency division selector 8, and FFT A processor 9 and a chirp signal generator 10 are provided.

  That is, in the configuration of the transmission system shown in FIG. 1, a wide band chirp signal is generated by the chirp signal generator 10, and the wide band chirp signal is FFT processed by the FFT processor 9 to convert it into a signal of frequency axis. Then, the frequency division selector 8 performs frequency division from f1 to fN, and randomly extracts from the divided frequencies so as to avoid duplication, and selects two series of the first signal sig1 and the second signal sig2. The IFFT processor 7 performs inverse Fourier transform on each of the two series of signals sig 1 and sig 2, and the modulation signal generator 6 generates a modulation signal on the time axis. On the other hand, the reference signal generator 5 generates a reference signal for obtaining a high frequency signal (RF signal), the modulator 4 modulates the reference signal from the modulation signal, the frequency converter 3 converts the frequency to an RF signal, The modulator 2 performs pulse modulation with a predetermined PRF and transmits from the transmitting antenna 1.

  On the other hand, the receiving system shown in FIG. 2 includes a receiving antenna 11, a frequency converter 12, an AD converter 13, a P1 signal extractor 14, an FFT processor (Fast-time) 15, a frequency selector 16a, a correlation processor (Fast -time) 17a, correlation result synthesizer 18, FFT processor (slow-time) 19, detector 20, Doppler extractor 21, P2 signal extractor 22, FFT processor (Fast-time) 23, frequency selector 24a , Correlation processor (Fast-time) 25a, correlation result synthesizer 25b, PRI column reordering device 26, Doppler reference signal corrector 27, correlation processor (slow-time) 28, detector 29, range extractor 30, An output processor 31 is provided.

  That is, in the configuration of the reception system shown in FIG. 2, the signal received by the antenna 11 is frequency converted to a baseband by the frequency converter 12 and converted to a digital signal by the AD converter 13. The received signal is input to the P1 signal extractor 14 and the P2 signal extractor 15, and the P1 signal and the P2 signal are respectively extracted to be separated into a signal sequence P1 and a signal sequence P2. Next, the separated signal strings P1 and P2 are converted into narrow band divided frequency signals by the FFT processors 15 and 23, respectively, and the signals of frequencies assigned in advance by the frequency selectors 16a and 24a are selected, and the correlation processor The correlation processing is performed for each divided frequency by 17a and 25a, and the correlation processing results are synthesized by the correlation result synthesis units 18 and 25b. The correlation result synthesis output on the P1 side is subjected to FFT by the FFT processor 19 to convert it into a signal of the frequency axis, and target detection is performed by the detector 20 by CFAR (non-patent document 6) or the like on the range-doppler axis, The Doppler frequency is extracted by the Doppler extractor 21 to obtain the velocity. On the other hand, the correlation result synthesis output on the P2 side is rearranged for each PRI column by the PRI column rearrangement unit 26, the Doppler reference signal correction unit 27 corrects the Doppler reference signal based on the Doppler extraction result, and correlation processing The correlation processing is performed by the unit 28, and the target detection by the CFAR or the like on the range-doppler axis is performed by the detector 29. Subsequently, the range is extracted from the target detection result by the range extractor 30, and the speed and range extracted by the output processor 31 are output in a predetermined format.

  Here, in this embodiment, in the transmission system, the transmission pulse is modulated with different first modulation signal P1 and second modulation signal P2, and the pulse P2 is modulated between the pulses, and the P1 and P2 columns are synthesized. A transmission pulse train P1 + P2 is generated. Among these methods, various methods such as SS modulation (Non-Patent Document 3) can be considered as a modulation method in a pulse for securing the isolation between the P1 and P2 columns. As one of the methods, there is a method using frequency division type. When this frequency division method is used, as shown in FIG. 4, the receiving system replaces the frequency selectors 16a and 24a with P1 selector 16 and P2 selector 24 for separating two types of signal strings, respectively. The correlation processors 17a and 25a are replaced with narrow band correlators (Fast-time) 17 and 25, respectively. In order to simplify the description, hereinafter, transmission will be mainly described with respect to the system of FIG. 1 and reception with the system of FIG. 4 in the case of frequency division type.

  First, a method of generating a transmission signal will be described with reference to FIGS. 1 and 5. In the transmission system, a wideband chirp signal is generated (10), converted to a signal of the frequency axis by FFT (9), and frequency division (f1 to fN) is performed (8). From the division frequency, it extracts at random so that there is no duplication, and selects two series of signals sig1 and sig2. For each of sig1 and sig2, inverse FFT is performed (7), and a modulation signal of time axis is generated (6). On the other hand, a reference signal for obtaining a high frequency signal (RF signal) is generated (5), this reference signal is modulated by the generated modulation signal (4), frequency converted to an RF signal (3), and predetermined PRF Pulse modulation (2) and transmission (1).

  It is as follows when the production | generation (6-10) of a modulation signal is formulated. The wideband chirp signal can be expressed by the following equation.

This is subjected to FFT to obtain a signal on the frequency axis.

This is frequency-divided, signals on the frequency axis of sig1 and sig2 are selected, and inverse FFT is performed to obtain signals Sig1 (t) and Sig2 (t) on the time axis.

  The inside of each pulse is modulated using Sig1 and Sig2. This is similar to modulation by frequency hopping (Non-Patent Document 4) in SS modulation (Non-Patent Document 3).

  This signal is then used to generate a pulse train. First, for Sig1, as shown at P1 in FIG. 3, in order to extract the Doppler, modulation is performed with the same code between the pulses. For Sig2, as shown by P2 in FIG. 3, in order to improve LPI performance by the inter-pulse code and to extract the range, modulation is performed between pulses using a random code (M sequence etc., Non-Patent Document 5). The signals of the P1 and P2 columns are synthesized to generate a transmission mixed waveform having different pulse widths and PRFs. The state of this mixed waveform is shown in FIG.

When combining P1 and P2, there may be a case where transmission pulses overlap. In this case, in order to make the transmission output of the transmission pulse constant, the overlapping portion may be treated as giving priority to either P1 or P2. The priority order may be alternated for each PRI.

  Next, reception will be considered based on the reception system of FIG. 4 (FIG. 2). The signal received by the antenna 11 is frequency converted (12), and becomes a digital signal by AD conversion (13). When this received signal is separated by signal sequence 1 and signal sequence 2, the following equation is obtained.

  The actual received signal has this composite waveform.

  Using this received waveform, as shown in FIG. 6, the signal sequence of each PRI is extracted (14, 22).

  This is subjected to FFT 15 and 23 on the fast-time axis.

  Sr1 and Sr2 each include a narrow band divided frequency signal, and are correlated for each divided frequency unit (17, 25). The reference signal can be calculated from equations (1) and (2).

This is subjected to FFT to obtain a signal on the frequency axis.

  Each Sref (ω) is divided into frequency division units.

  Similarly, each signal sequence is divided into frequency division units.

Next, each signal sequence is correlated (18, 26).

Next, the signal-to-noise ratio (SN) is improved by adding the signals for each frequency division. This situation is shown in FIG.

The correction phase is a phase value for correcting the phase due to the frequency difference for adding the signal for each frequency division band, and can be expressed by the following equation.

  The signal of the equation (15) is reduced in the number of samples by the frequency division as compared with the input signal, and corresponds to a low rate sampling signal.

  Next, in order to perform Doppler extraction using the signal string 1, FFT on the slow-time axis is performed for each cell on the fast-time axis as shown in P1 of FIG. 6 (19). This situation is shown in FIG.

  The Doppler fd (ω d = 2πfd) can be extracted by detecting (20) by using the Sr 1 (t, ω) and the like by the CFAR (Non-Patent Document 6) or the like on the range-Doppler axis (21). The speed can be converted by

  Next, a method of performing distance measurement using the signal string 2 will be described. The processing of the fast-time axis in each PRI is as shown in FIG.

  Since the signal train 2 has a different code for each pulse, the signals between the pulse trains are rearranged for each range cell as shown at P2 in FIG. 6 (26), and as shown in FIG. become.

The reference signal is as shown in the equation (4) including the correction (27) by the Doppler extracted in the signal sequence 1. In order to make the signal length equal to the equation (18), zero padding is performed.

Then it is FFTed.

  The correlation output is obtained by the following equation using equation (18) and equation (20) (28).

  As a result, a correlation output can be obtained on the range-slow-time axis, so that the target can be detected by the CFAR processing (29) and the target distance can be calculated (30) (see FIG. 10). This allows the target Doppler and distance to be output (31).

  As described above, in this embodiment, in the radar apparatus using modulation pulses by encoding or random signals (noise), the first pulse width for Doppler extraction, the first pulse train P1 of the first PRF, and the second for ranging The pulse width and the second pulse train P2 of the second PRF are combined, and in the first pulse train P1, the inside of the pulse is modulated by the first modulation signal, and in the second pulse train, the in-pulse modulation is performed by the second modulation signal different from the first pulse train. Furthermore, between pulses, a transmission signal modulated by the third modulation signal of random signal (noise) is transmitted from the antenna, and for the signal received by the antenna, the signal extracted by the first PRF is per PRI (fast-time axis) Then, the Doppler processing is extracted by FFT processing between PRFs (slow-time axis) using the correlation processing using the reference signal of the first modulation signal and the correlation processing. For the signal received by the antenna, the signal extracted by the second PRF is subjected to correlation processing for each PRI (fast-time axis) using the reference signal of the second modulation signal, and the correlation processing is used to obtain a signal within the PRI. A range is extracted by correlating the Doppler-corrected signal extracted by the first pulse train P1 with the third modulation signal between pulses using the signal train extracted for each of the range cells as a reference signal.

  That is, according to the radar apparatus of the above configuration, by using a transmission waveform in which signals having a plurality of pulse widths and PRFs are combined, in addition to wideband SS modulation, pulse widths and PRFs can be extracted more easily. While securing LPI property, distance measurement and speed measurement can be performed.

  Also, a Bn (n = 1 to M) signal in which the frequency band is N-divided by generating a chirp signal of band B as a modulated signal in the pulse of the first pulse train P1 and in the pulse of the second pulse train P2 The first and second signals subjected to the inverse FFT processing of the signals randomly extracted to about half (N1 and N2) so as not to overlap among the signals are used for the received signal in the first pulse train P1. The signal of the first PRI is subjected to FFT processing on the fast-time axis, and the result of combining narrowband signals (1 to N1) correlated with the reference signal for each division frequency used in the first signal is used to obtain the slow-time axis The second pulse train P2 performs FFT processing on the fast-time axis of the extracted second PRI signal in a narrow band in which the second pulse train P2 performs correlation processing with the reference signal for each division frequency used in the second signal. The result of combining the signals (1 to N1) Using, as a reference signal a signal corrected by the Doppler extracted by the first pulse train P1 to the modulation signal between pulses, by correlation, to range extraction.

  In this way, ranging in which high LPI characteristics are secured by making it difficult to extract pulse width and PRF in addition to wideband SS modulation using a transmission waveform in which signals having a plurality of pulse widths and PRFs are combined. Since speed measurement can be performed, and after correlation processing, a narrow band signal is obtained, so a signal with a low sampling rate can be obtained, and the HW scale can be reduced.

  In the present embodiment, a chirp signal is used as the modulation method of band B in the pulses of the first and second pulse trains, but in the case of a signal of band B, signals according to other modulation methods are used. Even if it uses, the same method can be applied.

Second Embodiment
The second embodiment will be described below with reference to FIGS. 11 to 13.

  In the first embodiment, when Doppler extraction and distance measurement are performed, addition is performed by correlating the first signal sequence or the second signal sequence with the reference signal every frequency division. In this case, particularly in the case of distance measurement, since the narrow band is used, the distance resolution decreases. Therefore, in the second embodiment, a method is described in which the distance resolution is improved by performing correlation processing with the wide band signal as it is when an increase in the processing scale due to the wide band is allowed.

  FIG. 11 shows the configuration of the reception system of the radar device according to this embodiment. In this case, the difference from the configuration of the receiving system shown in FIG. 4 is that the wide band correlation processors 17 a and 25 a are used instead of the narrow band correlation processors 17 and 25. That is, although processing for the first signal string P1 may be narrow band as in the first embodiment, the case of processing in a wide band to match with the second signal string P2 will be described here.

  For the first signal sequence P1 and the second signal sequence P2, correlation processing is performed over the entire frequency band without frequency division as described below instead of equations (12) to (15).

  First, with respect to the first signal string P1, the Doppler can be extracted and the velocity can be output by the same processing as the equations (16) and (17). Further, for the second signal string P2, by performing the processing of the equations (18) to (21), as shown in FIG. it can. Although this method can achieve high resolution of distance, since the second signal sequence P2 uses thinned frequencies in the frequency division unit, range side lobes occur. If this is acceptable. As shown in FIG. 13, correlation processing with a wide band signal can be applied.

  As described above, in the radar apparatus according to the present embodiment, the chirp signal in band B is generated as a modulation signal in the pulse of the first pulse train P1 and the pulse of the second pulse train P2, and FFT processing is performed to generate a frequency band. Of the N divided Bn (n = 1 to M) signals, using the first and second signals subjected to inverse FFT as the signals randomly extracted in about half (N1 and N2) so as not to be overlapped, On the other hand, in the first pulse train P1, the extracted signal of the first PRI is subjected to FFT processing in the fast-time axis, and the divided frequency signal used in the first signal is subjected to correlation processing using the wideband signal as the reference signal. The second pulse train P2 performs FFT processing on the axis for Doppler processing, and the second pulse train P2 performs FFT processing on the fast-time axis for the extracted second PRI signal and performs correlation processing on the divided frequency signal used for the second signal as a reference signal For Te, as a reference signal a signal corrected by the Doppler extracted by the first pulse train P1 to the modulation signal between pulses, by correlation, to range extraction.

  That is, according to the present embodiment, high LPI performance is ensured by making it difficult to extract pulse width and PRF in addition to wideband SS modulation using a transmission waveform in which signals having a plurality of pulse widths and PRFs are combined. While performing distance measurement and speed measurement, high-resolution distance measurement can be performed in order to perform correlation processing with a wide band signal.

Third Embodiment
The third embodiment will be described below with reference to FIGS. 14 to 16.

  In the first and second embodiments described above, the method of detecting the same correlation output by CFAR or the like even in the case of multiple reflection points in the detection of the correlation output of the signal sequence 2 has been described. In this case, when there is a signal of strong intensity such as clutter, there may be a case where a target signal with small intensity can not be extracted at the time of correlation processing. Therefore, in the present embodiment, a method of extracting a target signal even when a plurality of strong reflection points are included will be described.

  FIG. 14 shows the configuration of the reception system of the radar device according to this embodiment. This configuration differs from the reception system of the first embodiment shown in FIG. 4 in that the maximum value filter 32 which takes in the output of the detector 29, extracts the range of maximum amplitude, and returns it to the Doppler reference signal corrector 27 is The addition is made, and the equations (1) to (17) are the same as in the first and second embodiments, and the processing of the equations (18) to (21) for the signal string 2 is changed.

  First, CFAR or the like is applied to the correlation output of equation (21) for detection. The detection results are arranged in descending order of amplitude, and the distance is calculated for the point of maximum amplitude. Next, after removing the signal component of the maximum amplitude from equation (21), inverse FFT processing is performed.

Here, SUP [] represents to suppress the component of the maximum amplitude.

  The processes of (18) to (23) are repeated using the next different Doppler-corrected reference signal using this signal Sr2, to obtain a correlation output for each Doppler.

  FIG. 15 is a flow chart showing a flow of processing for obtaining correlation output for each Doppler using reference signals corrected by different Dopplers in the present embodiment. That is, in the present embodiment, first, Doppler extraction is performed in the first pulse train P1 (step S11), a reference signal is generated by the extracted Doppler (step S12), and correlation processing is performed on each Doppler (step S13). The second pulse train P2 extracts the range of the maximum amplitude (step S14). Here, it is determined whether the reflection point has ended (step S15). If the reflection point has ended, the maximum reflection point is deleted (step S16), and the process is continued from step S12. When the end of the reflection point is detected in step S15, the series of processing ends.

  As a result, it is possible to detect the signal of the reflected signal including clutter on the range-doppler axis. For example, in the case of a mounted radar, if the Doppler frequency range of the main lobe clutter is known, it is possible to distinguish clutter from the target. FIG. 16 shows how the clutter suppression range is set on the Doppler range axis based on the Doppler frequency range of the main lobe clutter and the clutter is discriminated from the target.

  As described above, in the radar apparatus according to this embodiment, when the correlation extraction is performed using the second signal sequence, after the signal having the maximum amplitude of the correlation value is extracted, the extracted signal is deleted, and the correlation processing is performed again I try to repeat the extraction.

  That is, according to the above configuration, when performing correlation extraction, after the signal having the maximum amplitude is extracted, it is deleted and the next correlation processing and extraction are repeated, so a signal with strong amplitude intensity such as clutter is It is possible to reduce the influence of low intensity signals becoming undetected.

  The present invention is not limited to the above embodiment as it is, and at the implementation stage, the constituent elements can be modified and embodied without departing from the scope of the invention. In addition, various inventions can be formed by appropriate combinations of a plurality of constituent elements disclosed in the above embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, components in different embodiments may be combined as appropriate.

DESCRIPTION OF SYMBOLS 1 ... Antenna, 2 ... Pulse modulator, 3 ... Frequency converter, 4 ... Modulator, 5 ... Reference signal generator, 6 ... Modulation signal generator, 7 ... IFFT, 8 ... Frequency division | segmentation selector, 9 ... FFT, 10 ... Chirp signal generator,
DESCRIPTION OF SYMBOLS 11 ... Antenna, 12 ... Frequency converter, 13 ... AD converter, 14 ... Code generator (P1 demodulation), 15 ... FFT (fast-time), 16 ... Frequency selector, 17 ... Narrow-band correlation processor (fast -time), 17a ... wideband correlation processor (fast-time), 18 ... correlation result synthesizer, 19 ... FFT (slow-time), 20 ... detector, 21 ... Doppler extractor, 22 ... code generator (P2 Demodulation), 23: FFT (fast-time), 24: frequency selector, 25: narrow band correlator (fast-time), 25a: broadband correlator (fast-time), 26: PRI sequence reorderer 26a: PRI column reordering device (P1 + P2) 27: Doppler reference signal corrector 28: correlation processor (slow-time) 29: detector 30: range extractor 31: output processor 32: Maximum value filter.

Claims (5)

A radar apparatus using a pulse train modulated by an encoding or random signal, comprising:
A first pulse width for Doppler extraction, a first pulse train of a first PRF (Pulse Repetition Frequency), a second pulse width for ranging and a second pulse train for a second PRF are combined, and in the first pulse train, In the second pulse train, modulation is performed with a modulation signal, intra-pulse modulation is performed with a second modulation signal different from the first pulse train, and a transmission signal modulated with a third modulation signal of a random signal is transmitted between transmission pulses from a transmission antenna. Transmission system,
The reception signal received by the reception antenna is subjected to correlation processing using the reference signal of the first modulation signal for each PRI (Pulse Repetition Interval) (fast-time axis), and correlation of the signal extracted by the first PRF is performed. Using the processed result, Doppler is extracted by FFT (Fast Fourier Transform) processing between the first PRF and the second PRF (slow-time axis), and then, with respect to the received signal, the second PRF is performed. The extracted signal is subjected to correlation processing for each PRI (fast-time axis) using the reference signal of the second modulation signal, and using the correlation processing result, a signal sequence extracted for each range cell in the PRI is used. A radar system comprising a reception system for correlating the third modulation signal between pulses with the signal corrected by the Doppler extracted by the first pulse train as a reference signal and extracting a range.   The reception system generates a signal in band B as the first modulation signal in the pulse of the first pulse train and the second modulation signal in the pulse of the second pulse train, performs FFT processing on the signal in N bands, and divides the frequency band into N Of the Bn (n = 1 to M) signals, using the first and second signals subjected to the inverse FFT processing for the signals randomly extracted to about half (N1 and N2) so as not to overlap, with respect to the received signal In the first pulse train, the extracted signal of the first PRI is subjected to FFT processing on the fast-time axis, and narrow band signals (1 to N1) subjected to correlation processing with the reference signal for each division frequency used for the first signal Using the synthesized result, Doppler processing is performed by FFT processing on the slow-time axis, and the second pulse train performs FFT processing on the fast-time axis of the extracted second PRI signal, and for each division frequency used in the second signal A narrowband signal correlated with the reference signal The third modulation signal between pulses is subjected to correlation processing as a reference signal to the third modulation signal between pulses, using the result obtained by combining 1 to N1) to perform range extraction. Radar apparatus as described.   The reception system generates a signal in band B as the first modulation signal in the pulse of the first pulse train and the second modulation signal in the pulse of the second pulse train, performs FFT processing on the signal in N bands, and divides the frequency band into N Of the Bn (n = 1 to M) signals, using the first and second signals subjected to the inverse FFT processing for the signals randomly extracted to about half (N1 and N2) so as not to overlap, with respect to the received signal In the first pulse train, the extracted signal of the first PRI is subjected to FFT processing on the fast-time axis, and the divided frequency signal used in the first signal is subjected to correlation processing using the wide-band signal as the reference signal. The second pulse train performs FFT processing on the fast-time axis by using FFT processing and Doppler processing for the second pulse train, and uses a broadband signal obtained by correlation processing using the divided frequency signal used in the second signal as a reference signal Between pulses The third reference signal a correction signal with Doppler extracted by the first pulse train to a modulated signal, by correlation, the radar apparatus according to claim 1, wherein the range extraction.   When the reception system performs the correlation process and the extraction process with the second signal, after the signal having the maximum amplitude of the correlation value is extracted, the extracted signal is deleted, and the correlation process and the extraction process are repeated again. The radar apparatus according to 2 or 3. A radar signal processing method for a radar device using a pulse train modulated by an encoding or random signal, comprising:
On the transmission side, the first pulse width for Doppler extraction, the first pulse train of the first PRF (Pulse Repetition Frequency), the second pulse width for ranging, and the second pulse train for the second PRF are combined, and in the first pulse train The inside is modulated with a first modulation signal, and in the second pulse train, intrapulse modulation is performed by a second modulation signal different from the first pulse train, and a transmission signal modulated with a third modulation signal of a random signal is transmitted between pulses. and when,
With respect to the reception signal of the reception antenna, the signal extracted by the first PRF is subjected to correlation processing and correlation processing using the reference signal of the first modulation signal every PRI (Pulse Repetition Interval) (fast-time axis) Using the results, Doppler is extracted by FFT (Fast Fourier Transform) processing between the first PRF and the second PRF (slow-time axis), and then, for the received signal of the receiving antenna, A signal extracted by 2PRF is subjected to correlation processing for each of the PRIs (fast-time axis) using the reference signal of the second modulation signal, and a signal extracted for each range cell in the PRI using the correlation processing result A radar signal processing method of a radar device, wherein a correlation is performed on a signal corrected by the Doppler extracted by the first pulse train into the third modulated signal between pulses using a train as a reference signal to extract a range.

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