WO2022085044A1 - Dispositif et procédé de traitement de signaux radar - Google Patents

Dispositif et procédé de traitement de signaux radar Download PDF

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WO2022085044A1
WO2022085044A1 PCT/JP2020/039224 JP2020039224W WO2022085044A1 WO 2022085044 A1 WO2022085044 A1 WO 2022085044A1 JP 2020039224 W JP2020039224 W JP 2020039224W WO 2022085044 A1 WO2022085044 A1 WO 2022085044A1
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unit
channel signals
imbalance correction
channel
band
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PCT/JP2020/039224
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English (en)
Japanese (ja)
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智也 山岡
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三菱電機株式会社
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Priority to PCT/JP2020/039224 priority Critical patent/WO2022085044A1/fr
Priority to JP2022556832A priority patent/JP7214061B2/ja
Publication of WO2022085044A1 publication Critical patent/WO2022085044A1/fr

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/88—Radar or analogous systems specially adapted for specific applications
    • G01S13/89—Radar or analogous systems specially adapted for specific applications for mapping or imaging
    • G01S13/90—Radar or analogous systems specially adapted for specific applications for mapping or imaging using synthetic aperture techniques, e.g. synthetic aperture radar [SAR] techniques

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  • This disclosure relates to a radar signal processing device.
  • the multi-channel synthetic aperture radar (hereinafter referred to as multi-channel SAR) is provided with a plurality of receiving antennas, so that a plurality of signals (hereinafter referred to as a plurality of channel signals) are received via a plurality of channels.
  • the multi-channel synthetic aperture radar generates a SAR image by performing a restoration process based on a plurality of received channel signals.
  • the multi-channel synthetic aperture radar corrects the amount of deviation between channel signals (hereinafter referred to as imbalance) caused by the difference in channels (for example, Non-Patent Document 1).
  • the azimuth ambiguity is multiplexed, and the above-mentioned is performed with sufficient accuracy. There is a problem that it becomes difficult to correct the imbalance between the channel signals of.
  • the present disclosure has been made to solve the above-mentioned problems, and an object of the present disclosure is to provide a technique for improving the accuracy of imbalance correction between channel signals.
  • the hit region band limiting unit and the hit region band limiting unit that limit the bandwidth in the hit region hit a plurality of channel signals obtained by observation by the multi-channel SAR, respectively. It includes an imbalance correction unit that performs imbalance correction between channel signals based on a plurality of channel signals for which band limitation has been performed in a region.
  • the accuracy of imbalance correction between channel signals can be improved.
  • FIG. 4A is a block diagram showing a hardware configuration that realizes the functions of the radar signal processing device according to the first embodiment.
  • FIG. 4B is a block diagram showing a hardware configuration for executing software that realizes the functions of the radar signal processing device according to the first embodiment.
  • FIG. 1 is a block diagram showing a configuration of a radar signal processing device 100 according to the first embodiment.
  • the radar signal processing device 100 includes a power imbalance correction unit 1, a fast Fourier transform unit 2, a Doppler frequency domain band limiting unit 3, an inverse fast Fourier transform unit 4, a hit region band limiting unit 5, and an in. It includes a balance correction unit 6, a sub-aperture division unit 9, a restoration algorithm unit 10, an image reproduction unit 11, and a sub-aperture coupling unit 12.
  • the power imbalance correction unit 1 corrects the power imbalance for a plurality of channel signals (raw data) obtained by observation by the multi-channel SAR.
  • the power imbalance correction unit 1 outputs a plurality of channel signals that have undergone power imbalance correction to the fast Fourier transform unit 2.
  • the "plurality of channel signals” means signals obtained from the corresponding channels among the plurality of channels in the multi-channel SAR, respectively.
  • power imbalance correction means to correct the amount of power deviation between channel signals caused by a channel difference.
  • the observation by the multi-channel SAR is a sliding spot observation.
  • the configuration in which the observation by the multi-channel SAR is the sliding spot observation will be described, but the observation by the multi-channel SAR may be, for example, a full spotlight observation or the like.
  • the fast Fourier transform unit 2 performs Doppler frequency conversion for each of a plurality of channel signals obtained by observation by the multi-channel SAR.
  • the fast Fourier transform unit 2 converts a plurality of channel signals obtained by observation by the multi-channel SAR into signals in the Doppler frequency domain by performing a fast Fourier transform. do.
  • the fast Fourier transform unit 2 performs Doppler frequency conversion for each of the plurality of channel signals for which the power imbalance correction unit 1 has performed the power imbalance correction.
  • the fast Fourier transform unit 2 outputs a plurality of channel signals that have undergone Doppler frequency conversion to the Doppler frequency domain band limiting unit 3.
  • the Doppler frequency domain band limiting unit 3 limits the band in the Doppler frequency domain for each of the plurality of channel signals for which the fast Fourier transform unit 2 has undergone the Doppler frequency conversion. More specifically, in the first embodiment, the Doppler frequency domain band limiting unit 3 extracts a channel signal in a band centered on the Doppler center frequency by band limiting in the Doppler frequency domain. The Doppler frequency domain band limiting unit 3 outputs a plurality of channel signals band-limited in the Doppler frequency domain to the inverse fast Fourier transform unit 4.
  • the inverse fast Fourier transform unit 4 (inverse Doppler frequency converter) performs inverse Doppler frequency conversion for each of a plurality of channel signals for which the Doppler frequency domain band limiting unit 3 has band-limited in the Doppler frequency domain.
  • the inverse fast Fourier transform unit 4 performs an inverse fast Fourier transform on each of a plurality of channel signals for which the Doppler frequency domain band limiting unit 3 has band-limited in the Doppler frequency domain, thereby performing a fast Fourier transform.
  • the transforming unit 2 converts the signal into the signal in the original time domain before performing the fast Fourier transform.
  • the inverse fast Fourier transform unit 4 outputs a plurality of channel signals subjected to the inverse Doppler frequency conversion to the hit region band limiting unit 5.
  • the hit area band limiting unit 5 limits the band in the hit area for each of the plurality of channel signals obtained by the observation by the multi-channel SAR. More specifically, in the first embodiment, the hit region band limiting unit 5 limits the bandwidth in the hit region for each of the plurality of channel signals subjected to the inverse Doppler frequency conversion by the inverse fast Fourier transform unit 4. .. More specifically, in the first embodiment, the hit region band limiting unit 5 extracts a channel signal in a band centered on the hit center by band limiting in the hit region. The hit area band limiting unit 5 outputs a plurality of channel signals for which the band is limited in the hit area to the imbalance correction unit 6.
  • the imbalance correction unit 6 performs imbalance correction between channel signals based on a plurality of channel signals for which the hit region band limiting unit 5 has band-limited in the hit region. More specifically, in the first embodiment, the imbalance correction unit 6 corrects the phase imbalance as the imbalance correction between the channel signals. The imbalance correction unit 6 outputs a plurality of channel signals for which imbalance correction has been performed to the sub-aperture division unit 9.
  • phase imbalance means the amount of phase shift between channel signals caused by the difference in channels.
  • the imbalance correction unit 6 corrects the phase imbalance as the imbalance correction will be described, but the imbalance correction unit 6 corrects the range sample deviation as the imbalance correction between the channel signals. May be done.
  • the imbalance correction unit 6 includes a Doppler center frequency estimation unit 7 and a phase imbalance correction unit 8.
  • the Doppler center frequency estimation unit 7 estimates the Doppler center frequencies of a plurality of channel signals for which the hit region band limiting unit 5 has band-limited in the hit region.
  • the Doppler center frequency estimation unit 7 outputs the estimated Doppler center frequency to the phase imbalance correction unit 8.
  • the phase imbalance correction unit 8 is based on the Doppler center frequency estimated by the Doppler center frequency estimation unit 7, and is based on a plurality of channel signals for which the hit region band limiting unit 5 has band-limited in the hit region. The phase imbalance of is corrected.
  • the phase imbalance correction unit 8 outputs a plurality of channel signals for which the phase imbalance has been corrected to the sub-aperture division unit 9.
  • the sub-aperture division unit 9 performs sub-aperture division for a plurality of channel signals for which the imbalance correction unit 6 has performed imbalance correction. More specifically, in the first embodiment, the sub-aperture division unit 9 divides the sub-aperture into a plurality of channel signals for which the phase imbalance correction unit 8 of the imbalance correction unit 6 has corrected the phase imbalance. I do. The sub-aperture division unit 9 outputs a plurality of channel signals obtained by sub-aperture division to the restoration algorithm unit 10.
  • the restoration algorithm unit 10 performs a restoration algorithm on a plurality of channel signals for which the sub-aperture division unit 9 has performed sub-aperture division.
  • the restoration algorithm unit 10 outputs a plurality of channel signals subjected to the restoration algorithm to the image reproduction unit 11.
  • the image reproduction unit 11 reproduces an image on a plurality of channel signals for which the restoration algorithm unit 10 has performed the restoration algorithm.
  • the image reproduction unit 11 outputs a plurality of channel signals for which image reproduction has been performed to the sub-aperture coupling unit 12.
  • the sub-aperture coupling unit 12 generates a SAR image by performing sub-aperture coupling on a plurality of channel signals for which the image reproduction unit 11 has reproduced an image. For example, the SAR image generated by the sub-aperture coupling portion 12 is displayed by a display (not shown).
  • FIG. 2 is a flowchart showing a radar signal processing method by the radar signal processing device 100 according to the first embodiment. Before each step described below, it is assumed that the radar signal processing device 100 has acquired a plurality of channel signals obtained by observation by the multi-channel SAR.
  • the power imbalance correction unit 1 performs power imbalance correction on a plurality of channel signals obtained by observation by the multi-channel SAR (step ST1).
  • the power imbalance correction unit 1 outputs a plurality of channel signals that have undergone power imbalance correction to the fast Fourier transform unit 2.
  • the fast Fourier transform unit 2 performs Doppler frequency conversion for each of the plurality of channel signals for which the power imbalance correction unit 1 has performed the power imbalance correction (step ST2).
  • the fast Fourier transform unit 2 outputs a plurality of channel signals that have undergone Doppler frequency conversion to the Doppler frequency domain band limiting unit 3.
  • the Doppler frequency domain band limiting unit 3 limits the band in the Doppler frequency domain for each of the plurality of channel signals subjected to the Doppler frequency conversion by the fast Fourier transform unit 2 (step ST3).
  • the Doppler frequency domain band limiting unit 3 outputs a plurality of channel signals band-limited in the Doppler frequency domain to the inverse fast Fourier transform unit 4.
  • the inverse fast Fourier transform unit 4 performs inverse Doppler frequency conversion for each of the plurality of channel signals for which the Doppler frequency domain band limiting unit 3 has band-limited in the Doppler frequency domain (step ST4).
  • the inverse fast Fourier transform unit 4 outputs a plurality of channel signals subjected to the inverse Doppler frequency conversion to the hit region band limiting unit 5.
  • the hit region band limiting unit 5 limits the bandwidth in the hit region for each of the plurality of channel signals for which the inverse fast Fourier transform unit 4 has undergone the inverse Doppler frequency conversion (step ST5).
  • the hit area band limiting unit 5 outputs a plurality of channel signals for which the band is limited in the hit area to the imbalance correction unit 6.
  • the Doppler center frequency estimation unit 7 of the imbalance correction unit 6 estimates the Doppler center frequency of a plurality of channel signals for which the hit region band limiting unit 5 has band-limited in the hit region (step ST6).
  • the Doppler center frequency estimation unit 7 outputs the estimated Doppler center frequency to the phase imbalance correction unit 8.
  • the phase imbalance correction unit 8 of the imbalance correction unit 6 corrects the phase imbalance between the channel signals based on the Doppler center frequency estimated by the Doppler center frequency estimation unit 7 (step ST7).
  • the phase imbalance correction unit 8 outputs a plurality of channel signals for which the phase imbalance has been corrected to the sub-aperture division unit 9.
  • the sub-aperture division unit 9 performs sub-aperture division for a plurality of channel signals for which the imbalance correction unit 6 has corrected the phase imbalance (step ST8).
  • the sub-aperture division unit 9 outputs a plurality of channel signals obtained by sub-aperture division to the restoration algorithm unit 10.
  • the restoration algorithm unit 10 performs a restoration algorithm on a plurality of channel signals for which the sub-aperture division unit 9 has undergone sub-aperture division (step ST9).
  • the restoration algorithm unit 10 outputs a plurality of channel signals subjected to the restoration algorithm to the image reproduction unit 11.
  • the image reproduction unit 11 reproduces an image on a plurality of channel signals for which the restoration algorithm unit 10 has performed the restoration algorithm (step ST10).
  • the image reproduction unit 11 outputs a plurality of channel signals for which image reproduction has been performed to the sub-aperture coupling unit 12.
  • the sub-aperture coupling unit 12 generates a SAR image by performing sub-aperture coupling on a plurality of channel signals for which the image reproduction unit 11 has reproduced an image (step ST11). For example, the SAR image generated by the sub-aperture coupling unit 12 in step ST11 is displayed by a display (not shown).
  • FIG. 3 is a diagram showing the progress of a channel signal processed by the radar signal processing method by the radar signal processing device 100 according to the first embodiment.
  • the plurality of channel signals obtained by the observation by the multi-channel SAR are the signals obtained by the two-channel sliding spotlight observation.
  • the first channel signal (channel 0 signal) before being processed by the radar signal processing device 100 is s 0 ( ⁇ , ⁇ ), and the second channel signal (channel 1 signal) is s 1 ( ⁇ , ⁇ ). ).
  • ⁇ is the range time and ⁇ is a hit.
  • the first channel signal will be used as a reference channel.
  • the power imbalance correction unit 1 has the following with respect to the first channel signal s 0 ( ⁇ , ⁇ ) and the second channel signal s 1 ( ⁇ , ⁇ ). Power imbalance correction is performed according to the method described in (For example, Non-Patent Document J. H. Kim, M. Younis, P. P. Iraola, M. Gebele, and G. Krieger, “First spaceborne demonstration of digital beamforming for azimuth ambiguity suppression”, IEEE. See Trans. Geosci. Remote Sens., Vol.51, no.1, pp.579-590, Jan., 2013).
  • the power imbalance correction unit 1 uses the first channel signal s 0 ( ⁇ , ⁇ ) and the second channel signal s 1 ( ⁇ , ⁇ ) to correct the power imbalance in the range frequency region. On the other hand, range frequency conversion is performed. As a result, the power imbalance correction unit 1 obtains S 0 ( fr , ⁇ ) and S 1 ( fr , ⁇ ) with the range frequency as fr .
  • the power imbalance correction unit 1 sets the noise power generated by the first channel signal as ⁇ 0 2 , and the noise power generated by the second channel signal as ⁇ 1 2 , according to the following equation (1).
  • the correction coefficient ⁇ ( fr ) of the power (amplitude) imbalance is calculated.
  • 2 ) indicates the average of
  • 2 ) indicates the average of
  • the power imbalance correction unit 1 corrects the amplitude of S 1 ( fr , ⁇ ) according to the following equation (2) based on the calculated correction coefficient ⁇ (fr).
  • the power imbalance correction unit 1 corrects the power imbalance by performing range time conversion on S 1 '( fr , ⁇ ) obtained by the equation (2).
  • the power imbalance correction unit 1 may use a method other than the method of the specific example as a method of correcting the power imbalance.
  • FIG. 3A shows a graph of the first channel signal s 0 ( ⁇ , ⁇ ) after the processing of step ST1.
  • the vertical axis in A indicates a hit
  • the horizontal axis indicates a range.
  • the raw data of the seven point images are multiplexed in the hit-range space.
  • the fast Fourier transform unit 2 has a Doppler frequency with respect to the first channel signal s 0 ( ⁇ , ⁇ ) and the second channel signal s 1 '( ⁇ , ⁇ ), respectively.
  • FIG. 3B shows a graph of the first channel signal after the processing of step ST2.
  • the vertical axis in B indicates the Doppler frequency
  • the horizontal axis indicates the range.
  • the first channel signal s 0 ( ⁇ , ⁇ ) is multiplexed with azimuth ambiguity.
  • the azimuth ambiguity is similarly multiplexed for the second channel signal s 1 '( ⁇ , ⁇ ).
  • FIG. 3C shows a graph of the first channel signal after the processing of step ST3.
  • the vertical axis in C in FIG. 3 indicates the Doppler frequency, and the horizontal axis indicates the range.
  • a signal near the Doppler center frequency is extracted by the process of step ST3.
  • a signal near the Doppler center frequency is similarly extracted by the process of step ST3.
  • step ST4 the inverse fast Fourier transform unit 4 performs inverse Doppler frequency conversion on the first channel signal and the second channel signal obtained by the processing of step ST3.
  • FIG. 3D shows a graph of the first channel signal after the processing of step ST4.
  • the vertical axis in D in FIG. 3 indicates a hit, and the horizontal axis indicates a range.
  • D in FIG. 3 in the first channel signal s 0 ( ⁇ , ⁇ ) after the processing of step ST4, the signals are discretely dispersed.
  • the signals of the second channel signal s 1 '( ⁇ , ⁇ ) after the processing of step ST4 are also discretely dispersed.
  • the hit region band limiting unit 5 has a hit region for each hit-range component of the first channel signal and the second channel signal obtained by the processing of step ST4.
  • FIG. 3E shows a graph of the first channel signal after the processing of step ST5.
  • the vertical axis in E in FIG. 3 indicates a hit, and the horizontal axis indicates a range.
  • E in FIG. 3 by suppressing the azimuth ambiguity, a signal from which the azimuth ambiguity is separated is obtained.
  • a signal from which the azimuth ambiguity is separated can be obtained similarly for the second channel signal s 1 '( ⁇ , ⁇ ).
  • the first channel signal obtained by the process of step ST5 is s 0 ( ⁇ , ⁇ )
  • the second channel signal is s 1 '( ⁇ , ⁇ ).
  • the imbalance correction unit 6 performs the first channel signal s 0 ( ⁇ , ⁇ ) and the second channel signal s 1 '( ⁇ ) obtained by the processing of step ST5. , ⁇ ), and corrects the phase imbalance between the channel signals according to the method described below (eg, H. Fan, Z. Zhang, and R. Wang, “phase mismatch calibration for multichannel sliding spotlight SAR). imaging with extended azimuth cross correlation ”, see IGARSS 2019).
  • step ST6 the Doppler center frequency estimation unit 7 of the imbalance correction unit 6 is based on the first channel signal s 0 ( ⁇ , ⁇ ) and the second channel signal s 1 '( ⁇ , ⁇ ). Then, two interference data C 1,0 ( ⁇ ) and C 0,1 ( ⁇ ) are calculated according to the following equations (3) and (4).
  • the PRF is the pulse repetition frequency and corresponds to one sample shift in the azimuth direction in the channel signal.
  • E ⁇ () indicates the average of the equations in parentheses in the hit direction, as described above.
  • the Doppler center frequency estimation unit 7 calculates the product C 1,0 ( ⁇ ) C 0,1 ( ⁇ ) of both the interference data C 1,0 ( ⁇ ) and C 0,1 ( ⁇ ). Therefore, the phase imbalance contained in s 1 '( ⁇ , ⁇ ) is offset. Assuming that the Doppler center frequency is f dc ( ⁇ ), the relationship of the following equation (5) is obtained.
  • the Doppler center frequency estimation unit 7 calculates the Doppler center frequency f dc ( ⁇ ) based on the calculated C 1,0 ( ⁇ ) C 0,1 ( ⁇ ) according to the following equation (6).
  • the phase imbalance correction unit 8 of the imbalance correction unit 6 has the following equation (7) based on the Doppler center frequency f dc ( ⁇ ) calculated by the Doppler center frequency estimation unit 7.
  • the phase imbalance ⁇ ( ⁇ ) is calculated according to the above.
  • vs represents the platform speed
  • d represents the distance between the reception phase centers of the two channels.
  • the phase imbalance correction unit 8 generates a weight for the obtained phase imbalance ⁇ ( ⁇ ) and performs a weighted averaging process so as to take an expected value in the hit direction. This process reduces the error in the estimated value. More specifically, first, the phase imbalance correction unit 8 calculates the average of
  • the phase imbalance correction unit 8 takes a weighted average according to the following equation (9) and calculates the phase imbalance ⁇ .
  • E ⁇ ⁇ indicates the average of the equations in parentheses in the range time direction.
  • the phase imbalance correction unit 8 corrects the phase imbalance between the channel signals according to the following equation (10) based on the calculated phase imbalance ⁇ . More specifically, in the specific example, the phase imbalance correction unit 8 has the second channel signal s after the power imbalance correction described above according to the following equation (10) based on the calculated phase imbalance ⁇ . Correct the phase imbalance for 1 '( ⁇ , ⁇ ).
  • the imbalance correction unit 6 may use a method other than the method of the specific example as a method of correcting the phase imbalance.
  • the sub-aperture dividing unit 9 has the second channel signal s 1 '' ( ⁇ , ⁇ ) and the first channel signal s 0 ( ⁇ , ⁇ ) after the processing of step ST7.
  • the method of sub-aperture division for example, the non-patent document J. Mittermayer, R. Lord, and E. B ⁇ oner, “Sliding spotlight SAR processing for TerraSAR-X using a new” fomulation of the extended chirp scaling algorithm, ”IGARSS2003, vol.3, p.1462-1464, 2003.).
  • the restoration algorithm unit 10 performs a restoration algorithm on the first channel signal and the second channel signal to which the sub-aperture division unit 9 has performed the sub-aperture division (reconstruction algorithm).
  • a restoration algorithm for the method, see, for example, Non-Patent Document 1 described above).
  • the image reproduction unit 11 reproduces an image with respect to the first channel signal and the second channel signal to which the restoration algorithm unit 10 has performed the restoration algorithm.
  • the image reproduction method include extended chirp scaling (for example, the above-mentioned non-patent documents J. Mittermayer, R. Lord, and E. B ⁇ oner, “Sliding spotlight SAR processing for TerraSAR-X using a”. See new fomulation of the extended chirp scaling algorithm, ”IGARSS2003, vol.3, p.1462-1464, 2003.).
  • the sub-aperture coupling unit 12 obtains a SAR image by performing sub-aperture coupling to the first channel signal and the second channel signal for which the image reproduction unit 11 has reproduced the image. Generate.
  • the imbalance correction unit 6 only corrects the phase imbalance in the subsequent stage of the band limitation by the bandpass filter twice, but the imbalance correction unit 6 corrects the range sample deviation and the like. Other imbalance corrections may be made.
  • the band path filters of the Doppler frequency domain band limiting unit 3 and the hit region band limiting unit 5 performed the band limitation twice, the Doppler frequency domain band limiting unit 3 did not limit the band of the Doppler frequency region.
  • the hit area band limiting unit 5 may limit the band only in the hit area.
  • Each function of the frequency estimation unit 7, the phase imbalance correction unit 8, the sub-aperture division unit 9, the restoration algorithm unit 10, the image reproduction unit 11, and the sub-aperture coupling unit 12 is realized by a processing circuit. That is, the radar signal processing device 100 includes a processing circuit for executing the processing of each step shown in FIG. This processing circuit may be dedicated hardware, or may be a CPU (Central Processing Unit) that executes a program stored in the memory.
  • CPU Central Processing Unit
  • FIG. 4A is a block diagram showing a hardware configuration that realizes the functions of the radar signal processing device 100.
  • FIG. 4B is a block diagram showing a hardware configuration for executing software that realizes the functions of the radar signal processing device 100.
  • the processing circuit 20 may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, or an ASIC (Application Specific Integrated Circuitd). Circuit), FPGA (Field-Programmable Gate Array) or a combination thereof is applicable.
  • ASIC Application Specific Integrated Circuitd
  • FPGA Field-Programmable Gate Array
  • Doppler center of power imbalance correction unit 1 Doppler center of power imbalance correction unit 1, fast Fourier transform unit 2, Doppler frequency domain band limiting unit 3, inverse fast Fourier transform unit 4, hit region band limiting unit 5, and imbalance correction unit 6 in the radar signal processing device 100.
  • the functions of the frequency estimation unit 7, the phase imbalance correction unit 8, the sub-aperture division unit 9, the restoration algorithm unit 10, the image reproduction unit 11, and the sub-aperture coupling unit 12 may be realized by separate processing circuits, or these may be realized. The functions may be collectively realized by one processing circuit.
  • the power imbalance correction unit 1 When the processing circuit is the processor 21 shown in FIG. 4B, the power imbalance correction unit 1, the fast Fourier transform unit 2, the Doppler frequency domain band limiting unit 3, the inverse fast Fourier transform unit 4, and the hit in the radar signal processing device 100.
  • the software or firmware is described as a program and stored in the memory 22.
  • the processor 21 By reading and executing the program stored in the memory 22, the processor 21 reads and executes the power imbalance correction unit 1, the fast Fourier transform unit 2, the Doppler frequency domain band limiting unit 3, and the inverse high-speed Fourier in the radar signal processing device 100. Conversion unit 4, hit region band limiting unit 5, Doppler center frequency estimation unit 7 and phase imbalance correction unit 8 of imbalance correction unit 6, sub-aperture division unit 9, restoration algorithm unit 10, image reproduction unit 11, and sub-aperture coupling. Each function of the part 12 is realized. That is, the radar signal processing device 100 includes a memory 22 for storing a program in which the processing of each step shown in FIG. 2 is executed as a result when each of these functions is executed by the processor 21.
  • These programs include a power imbalance correction unit 1, a high-speed Fourier transform unit 2, a Doppler frequency domain band limiting unit 3, an inverse fast Fourier transform unit 4, a hit region band limiting unit 5, and an imbalance correction in the radar signal processing device 100.
  • the computer is made to execute each procedure or method of the Doppler center frequency estimation unit 7 of the unit 6, the phase imbalance correction unit 8, the sub-aperture division unit 9, the restoration algorithm unit 10, the image reproduction unit 11, and the sub-aperture coupling unit 12.
  • the memory 22 uses the computer as a power imbalance correction unit 1, a fast Fourier transform unit 2, a Doppler frequency domain band limiting unit 3, an inverse fast Fourier transform unit 4, a hit region band limiting unit 5, and an algorithm in the radar signal processing device 100.
  • a program for functioning as the Doppler center frequency estimation unit 7 of the balance correction unit 6, the phase imbalance correction unit 8, the sub-aperture division unit 9, the restoration algorithm unit 10, the image reproduction unit 11, and the sub-aperture coupling unit 12 is stored. It may be a computer-readable storage medium.
  • the processor 21 corresponds to, for example, a CPU (Central Processing Unit), a processing device, a computing device, a processor, a microprocessor, a microcomputer, a DSP (Digital Signal Processor), or the like.
  • the memory 22 may include, for example, a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable Read Only Memory), an EPROM (Electrically-volatile) semiconductor, or an EPROM (Electrically-EPROM).
  • a RAM Random Access Memory
  • ROM Read Only Memory
  • flash memory an EPROM (Erasable Programmable Read Only Memory)
  • EPROM Electrically-volatile semiconductor
  • EPROM Electrically-EPROM
  • Doppler center of power imbalance correction unit 1 Doppler center of power imbalance correction unit 1, fast Fourier transform unit 2, Doppler frequency domain band limiting unit 3, inverse fast Fourier transform unit 4, hit region band limiting unit 5, and imbalance correction unit 6 in the radar signal processing device 100.
  • Some of the functions of the frequency estimation unit 7, the phase imbalance correction unit 8, the sub-aperture division unit 9, the restoration algorithm unit 10, the image reproduction unit 11, and the sub-aperture coupling unit 12 are realized by dedicated hardware, and some of them are realized. May be realized by software or firmware.
  • each function of the power imbalance correction unit 1, the fast Fourier transform unit 2, the Doppler frequency domain band limiting unit 3, the inverse fast Fourier transform unit 4, and the hit region band limiting unit 5 is a processing circuit as dedicated hardware. Realize the function.
  • the processor 21 is stored in the memory 22. The function may be realized by reading and executing the stored program.
  • the processing circuit can realize each of the above functions by hardware, software, firmware or a combination thereof.
  • the radar signal processing device 100 has the hit area band limiting unit 5 that limits the band in the hit area for each of the plurality of channel signals obtained by the observation by the multi-channel SAR. And an imbalance correction unit 6 that performs imbalance correction between channel signals based on a plurality of channel signals for which the hit region band limiting unit 5 has band-limited in the hit region.
  • a signal in which the azimuth ambiguity is separated can be obtained due to the band limitation in the hit region.
  • the accuracy of imbalance correction between channel signals can be improved.
  • the hit region band limiting unit 5 in the radar signal processing device 100 extracts a channel signal in a band centered on the hit center by band limiting in the hit region. According to the above configuration, a signal in which the azimuth ambiguity is separated can be obtained by band limitation for extracting the channel signal in the band centered on the hit center. By performing imbalance correction on the signal obtained thereby, the accuracy of imbalance correction between channel signals can be improved.
  • the radar signal processing device 100 has a high-speed Fourier conversion unit 2 that performs Doppler frequency conversion on a plurality of channel signals, and a plurality of channels that the high-speed Fourier conversion unit 2 performs Doppler frequency conversion.
  • the Doppler frequency domain band limiting unit 3 that limits the band in the Doppler frequency domain and the plurality of channel signals that the Doppler frequency domain band limiting section 3 band limits in the Doppler frequency domain, respectively.
  • Inverse high-speed Fourier conversion unit 4 that performs inverse Doppler frequency conversion, and the hit region band limiting unit 5 for each of a plurality of channel signals that the inverse high-speed Fourier conversion unit 4 has performed inverse Doppler frequency conversion.
  • Band limitation in the hit area For each of the signals, the Doppler frequency domain band limiting unit 3 that limits the band in the Doppler frequency domain and the plurality of channel signals that the Doppler frequency domain band limiting section 3 band limits in the Doppler frequency domain.
  • a signal in which the azimuth ambiguity is separated can be obtained due to the band limitation in the hit region and the band limitation in the Doppler frequency region.
  • the Doppler frequency domain band limiting unit 3 in the radar signal processing device 100 extracts a channel signal in a band centered on the Doppler center frequency by band limiting in the Doppler frequency domain.
  • a signal in which the azimuth ambiguity is separated can be obtained by band limitation for extracting the channel signal in the band centered on the Doppler center frequency.
  • the imbalance correction unit 6 in the radar signal processing device 100 corrects the phase imbalance as the imbalance correction. According to the above configuration, the accuracy of the phase imbalance correction between the channel signals can be improved by performing the phase imbalance correction on the signal whose azimuth ambiguity is separated by the band limitation.
  • the imbalance correction unit 6 in the radar signal processing device 100 may correct the range sample deviation as the imbalance correction. According to the above configuration, it is possible to improve the correction accuracy of the range sample deviation between the channel signals by correcting the range sample deviation for the signal whose azimuth ambiguity is separated by the band limitation.
  • the observation by the multi-channel SAR in the radar signal processing apparatus 100 according to the first embodiment is a sliding spot observation or a full spotlight observation. According to the above configuration, when the azimuth ambiguity is multiplexed by sliding spot observation or full spotlight observation, the accuracy of imbalance correction between channel signals can be improved.
  • a hit area band limiting step and a hit area band limiting step for band limiting in the hit region are performed for a plurality of channel signals obtained by observation by the multi-channel SAR, respectively.
  • the radar processing device can be used in the multi-channel SAR technique because it can improve the accuracy of imbalance correction between channel signals.
  • 1 power imbalance correction unit 1 power imbalance correction unit, 2 high-speed Fourier transform unit, 3 Doppler frequency domain band limiting unit, 4 inverse fast Fourier transform unit, 5 hit region band limiting unit, 6 imbalance correction unit, 7 Doppler center frequency estimation unit, 8 phase Imbalance correction unit, 9 sub-aperture division unit, 10 restoration algorithm unit, 11 image reproduction unit, 12 sub-aperture coupling unit, 20 processing circuit, 21 processor, 22 memory, 100 radar signal processing device.

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  • Engineering & Computer Science (AREA)
  • Remote Sensing (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • General Physics & Mathematics (AREA)
  • Radar Systems Or Details Thereof (AREA)

Abstract

L'invention concerne un dispositif de traitement de signaux radar (100) comprenant : une unité de limitation de bande de région de coïncidence (5) servant à limiter une bande dans une région de coïncidence par rapport à chaque signal d'une pluralité de signaux de canal obtenus par observation à l'aide d'un SAR multicanal ; et une unité de correction de déséquilibre (6) servant à corriger un déséquilibre entre des signaux de canal sur la base de la pluralité de signaux de canal qui ont été soumis à la limitation de bande dans la région de coïncidence par l'unité de limitation de bande de région de coïncidence (5).
PCT/JP2020/039224 2020-10-19 2020-10-19 Dispositif et procédé de traitement de signaux radar WO2022085044A1 (fr)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006343290A (ja) * 2005-06-10 2006-12-21 Mitsubishi Electric Corp 画像レーダ装置
JP2015001428A (ja) * 2013-06-14 2015-01-05 三菱電機株式会社 レーダ信号処理装置及びレーダ信号処理方法
WO2016148104A1 (fr) * 2015-03-16 2016-09-22 三菱電機株式会社 Dispositif et procédé de création d'image radar animée

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006343290A (ja) * 2005-06-10 2006-12-21 Mitsubishi Electric Corp 画像レーダ装置
JP2015001428A (ja) * 2013-06-14 2015-01-05 三菱電機株式会社 レーダ信号処理装置及びレーダ信号処理方法
WO2016148104A1 (fr) * 2015-03-16 2016-09-22 三菱電機株式会社 Dispositif et procédé de création d'image radar animée

Non-Patent Citations (3)

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Title
FAN, HUAITAO ET AL.: "Phase Mismatch Calibration for Multichannel Sliding Spotlight SAR Imaging with Extended Azimuth Cross Correlation", IGARSS 2019-2019 IEEE INTERNATIONAL GEOSCIENCE AND REMOTE SENSING SYMPOSIUM, August 2019 (2019-08-01), pages 2531 - 2534, XP033656916, DOI: 10.1109/IGARSS.2019.8900075 *
WU, DI ET AL.: "A Channel Calibration Algorithm Based on Isolated Scatterers for Multi-Channel HRWS-SAR", IEEE ACCESS, vol. 7, 2019, pages 135665 - 135677, XP011747900, DOI: 10.1109/ACCESS.2019.2941203 *
ZHOU, YASHI ET AL.: "A Novel Approach to Doppler Centroid and Channel Errors Estimation in Azimuth Multi-Channel SAR", IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING, vol. 57, no. 11, November 2019 (2019-11-01), pages 8430 - 8444, XP011755607, DOI: 10.1106/TGRS.2019.2921094 *

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