WO2017154205A1 - Dispositif de détection de cible mobile - Google Patents

Dispositif de détection de cible mobile Download PDF

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Publication number
WO2017154205A1
WO2017154205A1 PCT/JP2016/057787 JP2016057787W WO2017154205A1 WO 2017154205 A1 WO2017154205 A1 WO 2017154205A1 JP 2016057787 W JP2016057787 W JP 2016057787W WO 2017154205 A1 WO2017154205 A1 WO 2017154205A1
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Prior art keywords
unit
moving target
sub
aperture
sar
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PCT/JP2016/057787
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English (en)
Japanese (ja)
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聖平 中村
享介 河端
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三菱電機株式会社
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Priority to JP2017547192A priority Critical patent/JP6381825B2/ja
Priority to PCT/JP2016/057787 priority patent/WO2017154205A1/fr
Publication of WO2017154205A1 publication Critical patent/WO2017154205A1/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
    • G01S13/9021—SAR image post-processing techniques
    • G01S13/9029—SAR image post-processing techniques specially adapted for moving target detection within a single SAR image or within multiple SAR images taken at the same time
    • 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
    • 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
    • G01S13/9021—SAR image post-processing techniques
    • G01S13/9023—SAR image post-processing techniques combined with interferometric techniques

Definitions

  • the present invention relates to a moving target detection apparatus that detects a moving target signal from signals received at a plurality of antenna openings.
  • Two or more antenna apertures are arranged in the direction of travel of the platform (hereinafter referred to as the along track direction), and a synthetic aperture radar (SAR: Synthetic Aperture Radar) is used by using signals received at each antenna aperture.
  • SAR Synthetic Aperture Radar
  • a method is known in which a moving target is detected by suppressing a stationary target signal using a combination of these images after generating an image (see, for example, Non-Patent Document 1).
  • Non-Patent Document 2 As a method using two antenna openings, for example, a moving target detection method described in Non-Patent Document 2 is known.
  • SAR images are generated by using signals received at two antenna apertures, and the imbalance between channels of the two generated SAR images is corrected, and then the two SAR images are aligned.
  • the difference or phase difference of the complex amplitude is calculated, and a difference image or a phase difference image is generated.
  • Non-Patent Document 2 in order to detect the movement target signal, the difference between the stationary target or the pixel having the large absolute value in the difference image and the pixel having the large phase difference in the phase difference image are detected. Threshold processing is performed with a threshold value calculated from the probability density function of the phase difference, and a pixel having a pixel value equal to or greater than the threshold value is detected as a movement target.
  • the present invention has been made to solve such a problem, and an object of the present invention is to provide a moving target detection apparatus capable of detecting a moving target with high accuracy.
  • a moving target detection device includes a radar device that obtains each reception signal obtained by receiving pulse signals irradiated to an observation range with three or more antennas, a SAR image generation unit that generates each SAR image of each reception signal, and A motion measurement unit that measures the speed of the platform on which the antenna is mounted, and a registration unit that aligns each SAR image generated by the SAR image generation unit using the platform speed information measured by the motion measurement unit; The SAR images aligned by the registration unit are compared to correct the amplitude and phase imbalance of each SAR image, and the phase difference between each SAR image corrected by the signal calibrating unit. And a moving target detecting unit that detects the moving target by calculating and comparing the calculated phase difference.
  • the moving target detection apparatus is configured to calculate a phase difference by interfering signals of each aligned SAR image and detect a moving target from the variation in the phase difference.
  • FIG. 1 is a block diagram of a moving target detection apparatus according to this embodiment.
  • the moving target detection apparatus according to the present embodiment includes a radar apparatus 10, a signal processing unit 20, and a motion measurement unit 30, as shown in the figure.
  • the radar apparatus 10 is an apparatus for obtaining each received signal obtained by receiving a pulse signal irradiated to an observation range with three or more antennas.
  • the signal processing unit 20 is a processing unit for detecting a movement target using the received signal acquired by the radar apparatus 10 and the platform motion information measured by the motion measurement unit 30, and in FIG.
  • the functional block configuration is shown.
  • the illustrated signal processing unit 20 includes a SAR image generation unit 21, a registration unit 22, a signal calibration unit 23, and a movement target detection unit 24.
  • the SAR image generation unit 21 is a processing unit that generates each SAR image of each reception signal received by the radar apparatus 10.
  • the registration unit 22 is a processing unit that aligns each SAR image generated by the SAR image generation unit 21 using speed information in the platform motion information measured by the motion measurement unit 30.
  • the signal calibrating unit 23 is a processing unit that compares the SAR images aligned by the registration unit 22 and corrects the amplitude and phase imbalance of the SAR images.
  • the transmission / reception switch 105 switches the transmission / reception antenna 106 between a transmission state and a reception state.
  • the transmission / reception antenna 106 is an antenna for irradiating the pulse signal acquired from the amplification unit 102 to the atmosphere, and irradiates the pulse signal to the atmosphere.
  • the pulse signal irradiated into the atmosphere is irradiated and scattered on a scatterer such as the ground surface.
  • the transmitting / receiving antenna 106 and the receiving antennas 107a and 107b receive signals scattered by the scatterers.
  • the signal received by the transmission / reception antenna 106 is output to the reception unit 103 via the transmission / reception switch 105.
  • signals received by the receiving antennas 107 a and 107 b are output to the receiving unit 103.
  • the receiving unit 103 is a processing unit that extracts a baseband signal from an RF (Radio Frequency) signal, and the extracted baseband signal is output to the data recording unit 104.
  • the data recording unit 104 is a recording unit for a signal acquired from the receiving unit 103.
  • the input signal is A / D (Analog-to-Digital) converted by the A / D conversion unit 104a to perform predetermined sampling. It converts into the signal for every rate, and the converted signal is output to the memory
  • the motion measurement unit 30 is mounted on the same platform as the radar device 10, and the position of the IMU (Internal Measurement Unit) and the platform that measures the three-axis angle (or angular velocity) and acceleration governing motion as platform motion information. It is comprised by the apparatus which measures the position of a platform, an attitude angle, etc., such as GPS (Global Positioning System) which outputs, and a magnetic compass which outputs azimuth information, and acquires speed information of a platform at least. In addition, for more accurate observation, it is desirable that the motion measurement unit 30 can measure the position, speed, and posture of the platform.
  • the exercise information acquired by the exercise measuring unit 30 is output to the storage device 207 in the signal processing unit 20.
  • the signal processing unit 20 includes a processor 201, a controller 202, a controller interface 203, a memory 204, a display interface 205, a display 206, and a storage device 207.
  • the processor 201 is a processor for realizing the functions of the SAR image generation unit 21 to the movement target detection unit 24 shown in FIG. 1 and via the controller interface 203, the controller 202.
  • the control signal from the storage device 207 is received, and the received signal from the storage device 207, the exercise information, the processing program, and the like are read into the memory 204 and the operation is performed.
  • the result of the movement target detection process by the processor 201 is output to the display 206 via the display interface 205.
  • the controller 202 outputs a control signal to each part of the radar apparatus 10 and the processor 201, and controls the movement target detection apparatus.
  • the SAR image generation unit 21 to the movement target detection unit 24 in the signal processing unit 20 shown in FIG. 1 store programs corresponding to the respective processing units in the storage device 207, and the processor 201 stores these programs in the memory 204. It is realized by reading in and executing.
  • the antenna having the reception function is described as three antennas, that is, the transmission / reception antenna 106 and the reception antennas 107a and 107b.
  • the number is not limited as long as the number is three or more.
  • the receiving unit 103 and the data recording unit 104 have a function of simultaneously receiving and recording data for the number of reception channels.
  • FIG. 3 is an explanatory diagram showing the geometry of observation by the moving target detection apparatus according to Embodiment 1 of the present invention.
  • the observation signal of the moving target detection apparatus according to the first embodiment will be described with reference to FIG.
  • reference numeral 106 denotes a transmission / reception antenna
  • 107a and 107b denote reception antennas
  • Reference numeral 300 denotes a movement target.
  • the transmission / reception antenna 106, the reception antenna 107a, and the reception antenna 107b are mounted on the same platform, for example.
  • the transmitting / receiving antenna 106, the receiving antenna 107a, and the receiving antenna 107b are arranged in a line along the traveling direction of the platform.
  • the transmission / reception antenna 106, the reception antenna 107a, and the reception antenna 107b do not have to be mounted on the same platform, and may be mounted on different platforms. It shall move in a line.
  • a moving body such as an aircraft, an artificial satellite, and a vehicle.
  • an aircraft is assumed as a platform, and the description will proceed with the geometry of the aircraft in mind.
  • the technology disclosed in this specification can be applied to observations using platforms such as artificial satellites and vehicles as well as aircraft. Yes, it does not limit the platform type.
  • the distance between the transmission / reception antenna 106 and the reception antenna 107a is L 1
  • the distance between the transmission / reception antenna 106 and the reception antenna 107b is L 2
  • ⁇ n is the off-nadir angle
  • V r [m / s] is the speed of the platform. It is assumed that the moving target detection device described in this specification has a squint angle of 0 degrees. That is, in the case of strip map mode observation, the irradiation direction of the antenna beam is always perpendicular to the traveling direction of the platform. In the case of spotlight mode observation and sliding spotlight mode observation, at the center of the synthetic aperture. It is assumed that the direction of the antenna beam is a direction orthogonal to the traveling direction.
  • the time is expressed in ⁇ [seconds].
  • the platform traveling direction is the x axis
  • the horizontal plane is orthogonal to the x axis
  • the left direction with respect to the traveling direction is positive.
  • a coordinate system is defined in which the axis is the y-axis and the vertical upward direction is the z-axis.
  • the altitude of the platform is h
  • the distance R 1 ( ⁇ ) between the transmitting / receiving antenna 106 and the moving target 300 at time ⁇ is expressed by the following equation. Is done.
  • R 0 is represented by the following formula.
  • v g0 [m / s] is defined by the following equation.
  • the x-axis direction parallel to the platform trajectory may be referred to as the along track direction.
  • the cross-track direction component of the moving target speed component is the same as that of the moving target speed in the line-of-sight direction of the radar. Match the ingredients.
  • ⁇ 1 is the position of the phase center when the transmission / reception antenna 106 transmits radio waves and the reception antenna 107a receives radio waves from the time when the transmission / reception antenna 106 is at the position of (V r ⁇ , 0, 0).
  • the time difference until the position (V r ⁇ , 0, 0) is reached is shown.
  • ⁇ 2 is the position of the phase center when the transmission / reception antenna 106 transmits radio waves and the reception antenna 107b receives radio waves from the time when the transmission / reception antenna 106 is at the position of (V r ⁇ , 0, 0).
  • ⁇ 1 and ⁇ 2 are given by the following equations, respectively.
  • the baseline length L 1 from the transmission / reception antenna 106 to the reception antenna 107 a and the baseline length L 2 from the transmission / reception antenna 106 to the reception antenna 107 b are the distance R 0 between the transmission / reception antenna 106 and the moving target 300. This is true under sufficiently short conditions.
  • L 1 and L 2 are the physical distance from the transmitting and receiving antenna 106 to the reception antenna 107b from the receiving antenna 107a and the transmitting and receiving antenna 106
  • d 1 And d 2 are the phase center and the transmission / reception antenna when the transmission / reception antenna 106 transmits a radio wave from the position of the electrical phase center when transmission / reception is performed by the transmission / reception antenna 106 and then the reception antenna 107a receives the radio wave.
  • the distance from the transmission of the radio wave at 106 to the center of the phase when the radio wave is received by the receiving antenna 107a is shown.
  • the position of the movement target 300 in the cross track direction is R 0 + v g0 ( ⁇ + ⁇ 1 ), respectively.
  • the position of the movement target 300 in the cross track direction is R 0 + v g0 ( ⁇ + ⁇ 2 ), respectively.
  • a signal obtained by transmitting a signal from the transmission / reception antenna 106, reflected by the movement target 300, and range-compressed by the transmission / reception antenna 106, the reception antenna 107a, and the reception antenna 107b is expressed by the following equation.
  • a 1 ( ⁇ ), a 2 ( ⁇ ), and a 3 ( ⁇ ) are amplitudes of received signals at the transmitting / receiving antenna 106, the receiving antenna 107a, and the receiving antenna 107b, respectively.
  • the signal S i ( ⁇ ) (i 1,2,3)
  • the reception signal s 2 ( ⁇ ) is not an observation signal at time ⁇ but a signal at ⁇ + ⁇ 1 .
  • the received signal s 3 ( ⁇ ) is a signal at ⁇ + ⁇ 2 .
  • n 1 ( ⁇ ), n 2 ( ⁇ ), and n 3 ( ⁇ ) are noises at time ⁇ .
  • pulses are transmitted at a certain cycle (this is called a pulse repetition cycle). Since the transmitted pulse reflected in the observation range including the moving target 300 is received by the transmission / reception antenna 106, the reception antenna 107a, and the reception antenna 107b, the signals actually observed are s 1 ( ⁇ ) and s 2 ( ⁇ ) and s 3 ( ⁇ ) are discretized with a pulse repetition period. In this specification, s 1 ( ⁇ ), s 2 ( ⁇ ), and s 3 ( ⁇ ) are used unless particularly confusing. As a continuous signal. However, when s 2 ( ⁇ ) and s 3 ( ⁇ ) are obtained, it should be noted that signal interpolation processing is required.
  • phase difference between the signal s 1 ( ⁇ ), the signal s 2 ( ⁇ ), and the signal s 3 ( ⁇ ) is calculated as shown in the following equation by causing the signals to interfere as in the conventional ATI method.
  • R 2 ( ⁇ ) ⁇ R 1 ( ⁇ ) in the above equation (8) is obtained by transmitting a radio wave from the transmission / reception antenna 106 from the time when the transmission / reception antenna 106 is located at (V r ⁇ , 0, 0), and receiving antenna 107a.
  • 3 represents a change in distance that occurs due to the movement of the moving target 300 to the time difference ⁇ 1 until the position of the phase center when the radio wave is received reaches the position of (V r ⁇ , 0, 0).
  • R 3 ( ⁇ ) ⁇ R 2 ( ⁇ ) is a case where a radio wave is transmitted from the transmission / reception antenna 106 at a time at a position of (V r ⁇ , 0,0) and then received by the reception antenna 107a.
  • R 3 ( ⁇ ) ⁇ R 1 ( ⁇ ) is a value obtained by transmitting a radio wave from the transmission / reception antenna 106 at a time when the transmission / reception antenna 106 is located at (V r ⁇ , 0, 0) and This is a distance change caused by the movement of the moving target 300 to the time difference ⁇ 2 until the position of the phase center at the time of reception reaches the position of (V r ⁇ , 0, 0).
  • phase differences ⁇ 12 ( ⁇ ), ⁇ 23 ( ⁇ ), and ⁇ 13 ( ⁇ ) shown in the above equation (8) indicate that the moving target 300 is ⁇ 1 , ⁇ 2 ⁇ 1 , ⁇ 2 . It is a value according to the distance traveled in time, and depends on the speed v g0 .
  • the phase differences ⁇ 12 ( ⁇ ) and ⁇ 23 ( ⁇ ) have the same value.
  • phase differences ⁇ 12 ( ⁇ ) and ⁇ 23 ( ⁇ ) of a stationary target are always zero.
  • the phase differences ⁇ 12 ( ⁇ ) and ⁇ 23 ( ⁇ ) do not become zero even for a stationary target.
  • the above is the principle of moving target detection by the moving target detection device according to the first embodiment.
  • the description is given in the form of using three antenna openings.
  • the moving target detection method using the moving target detection apparatus according to the first embodiment has four or more antenna openings. However, it can be easily expanded.
  • the SAR image generation unit 21 generates SAR images using the received signals received by the respective reception antennas and the platform speed information measured by the motion measurement unit 30.
  • the methods described in Non-Patent Document 1 and the like can be used. However, these methods are publicly known, and thus the description thereof is omitted here.
  • ⁇ [seconds] represents the range direction axis of the SAR image in terms of time, and is called “Fast time”.
  • ⁇ [seconds] is the observation time as described above, and represents the azimuth direction axis of the SAR image by time, and is called Slow time.
  • the distance r [m] in the range direction, the distance a [m] in the azimuth direction, ⁇ , and ⁇ each satisfy the following relationship.
  • c is the speed of light.
  • SAR SAR image generated by the image generator 21 is one which is discretized, x 1 (m ⁇ , n ⁇ ) , x 2 (m ⁇ , n ⁇ ), x 3 (m ⁇ , n ⁇ ) is range direction, azimuth It is an expression that is sampled and discretized at intervals of ⁇ and ⁇ , respectively.
  • M and N are the numbers of pixels in the range direction and the azimuth direction, respectively.
  • the registration unit 22 performs resampling so as to compensate for the shift amounts ⁇ 1 and ⁇ 2 in the azimuth direction expressed by the equation (6), and as shown by the following equation, the SAR image z 1 ( m ⁇ , n ⁇ ), z 2 (m ⁇ , n ⁇ ), and z 3 (m ⁇ , n ⁇ ) are obtained.
  • z 1 (m ⁇ , n ⁇ ), z 2 (m ⁇ , n ⁇ ), and z 3 (m ⁇ , n ⁇ ) may have a bias error added to the amplitude and phase due to the difference in gain of the receiver. Therefore, the signal calibration unit 23 estimates and compensates for each phase and amplitude bias error from the ratio between the SAR images after alignment.
  • ⁇ 12 and ⁇ 13 are defined by the following equations.
  • the signal calibrating unit 23 corrects the amplitude and phase imbalance between the SAR images by the following equation using the correction coefficient represented by the equation (12).
  • ⁇ 12 and ⁇ 13 are measured in advance as correction coefficients and can be stored in the storage device 207, it is not necessary to estimate these values using equation (12).
  • equation (12) when the terrain phase due to a slight difference in antenna height cannot be ignored, it is necessary to correct using, for example, the method described in Japanese Patent Application Laid-Open No. 2010-175330.
  • ⁇ 12 and ⁇ 13 are described in the form of constants.
  • ⁇ 12 and ⁇ 13 are not necessarily constant for each pixel. It is a function of the pixel number.
  • description will be made assuming that the topographic phase is also corrected.
  • the movement target detection unit 24 calculates the phase difference by causing the signals of each SAR image to interfere with each other as in the following equation.
  • ⁇ th is a threshold value for detecting the moving target, and is input from the controller 202. Further, it may be held in the storage device 207.
  • the speed in the line-of-sight direction of each pixel of the SAR image calculated from the phase difference between the SAR images calculated by the above equation (17) is an estimated speed if the moving target 300 is a constant speed moving target.
  • the radar apparatus that obtains each reception signal obtained by receiving the pulse signal irradiated to the observation range with three or more antennas, and each SAR of each reception signal.
  • the SAR image registered in the registration unit is compared with the SAR image aligned in the registration unit, and the signal calibrating unit corrects the amplitude and phase imbalance of each SAR image, and is corrected in the signal calibrating unit.
  • a moving target detector that detects a moving target by calculating a phase difference between the respective SAR images and comparing the calculated phase difference.
  • the moving target detection unit calculates the standard deviation of the calculated phase difference, and detects the moving target by thresholding the standard deviation.
  • the moving target detection process can be performed easily and reliably.
  • the moving target detection unit detects the moving target by calculating the speed in the range direction from the calculated phase difference and comparing the calculated speed values. Since it did in this way, the detection process of a movement target can be performed easily and reliably.
  • the moving target detection unit calculates the speed in the range direction from the calculated phase difference, calculates the standard deviation of the calculated speed, and performs threshold processing on the standard deviation.
  • the moving target is detected, so that the moving target detection process can be performed easily and reliably.
  • FIG. FIG. 4 is a hardware configuration diagram of the movement target detection apparatus according to the second embodiment.
  • the moving target detection apparatus shown in FIG. 4 includes a radar apparatus 10a and a signal processing unit 20a.
  • the radar apparatus 10 a includes an excitation unit 101, an amplification unit 102, a reception unit 103, a data recording unit 104, a transmission / reception switch 105, a transmission / reception antenna 106, a reception antenna 107, and a motion measurement unit 30.
  • the difference from the radar apparatus 10 of the first embodiment shown in FIG. 2 is that there is only one receiving antenna 107, that is, the second embodiment has two antennas having a receiving function.
  • the receiving unit 103 and the data recording unit 104 have a function of simultaneously receiving and recording data for the number of reception channels.
  • FIG. 5 is a functional block diagram showing a configuration for realizing the movement target detection process in the signal processing unit 20a.
  • the signal processing unit 20a according to the second embodiment includes a sub-aperture divided type movement target detection unit 25 in place of the movement target detection unit 24 of the first embodiment.
  • the other configuration is the same as the configuration shown in FIG. 1, and accordingly, the same reference numerals are given to the corresponding portions and the description thereof is omitted.
  • the sub-aperture split type movement target detection unit 25 is a processing unit configured to detect a movement target based on the phase difference for each sub-aperture, and FIG. 6 shows an internal configuration.
  • the sub-aperture division type moving target detection unit 25 includes an azimuth decompression unit 251, a sub-aperture division unit 252, a sub-aperture compression unit 253, a sub-aperture phase difference calculation unit 254, and a sub-aperture movement target detection unit 255.
  • the azimuth decompression unit 251 is a processing unit that performs azimuth decompression processing on the SAR image corrected by the signal calibration unit 23.
  • the sub-aperture dividing unit 252 is a processing unit that divides the data that has been subjected to azimuth compression by the azimuth decompressing unit 251 into sub-apertures.
  • the sub-aperture compression unit 253 is a processing unit that azimuth-compresses the data of each sub-aperture divided by the sub-aperture division unit 252 again.
  • the sub-aperture phase difference calculation unit 254 is a processing unit that calculates the phase difference between the SAR images of each sub-aperture compressed by the sub-aperture compression unit 253.
  • the sub-aperture movement target detection unit 255 is a processing unit that detects the movement target by comparing the phase differences for each sub-aperture calculated by the sub-aperture phase difference calculation unit 254.
  • the azimuth decompression unit 251 returns the azimuth-compressed SAR image to the state before the azimuth compression by convolving the complex conjugate of the azimuth reference function used for the azimuth compression of the SAR image generation by the SAR image generation unit 21. Note that details of the azimuth compression processing and the azimuth reference function are known as described in Non-Patent Document 1, Non-Patent Document 2, and the like, and thus description thereof is omitted here.
  • the signal after azimuth decompression output from the azimuth decompression unit 251 is expressed by the following equation.
  • the sub-aperture dividing unit 252 sets a hit number corresponding to the sub-aperture to be processed in the next sub-aperture compression unit 253 for the signal of the azimuth line before azimuth compression obtained by the azimuth decompression unit 251.
  • the hit data is extracted.
  • FIG. 7 shows the relationship between the slow time hit number and the sub-aperture number divided by the sub-aperture dividing unit 252.
  • reference numeral 701 denotes one of SAR data obtained by solving the azimuth compression in the azimuth decompression unit 251.
  • the horizontal axis ⁇ [seconds] is a time (slow time) representing the axis in the azimuth direction.
  • the sub-aperture compression unit 253 a signal in a range surrounded by a broken line is cut out from the SAR data after azimuth decompression, and azimuth compression processing is performed again.
  • the range surrounded by the broken line that is cut out is called a sub-aperture.
  • the sub-aperture compression unit 253 applies azimuth compression processing to each extracted signal while moving the sub-aperture in the azimuth time axis direction (slow time) direction.
  • the sub-aperture compression unit 253 again performs azimuth compression on the data divided by the sub-aperture division unit 252 in units of sub-apertures.
  • An output signal obtained by azimuth compression by the sub-aperture compression unit 253 is expressed by the following equation. Note that N sub is the number of points in the azimuth direction of each sub-aperture, and N sp is the number of sub-apertures.
  • th sub is a threshold for calculating the moving target, input or by the controller 202, which is set in such pre-value was held in the storage device 207, the means is not limited.
  • Embodiment 2 it has been described that two or more SAR antennas are received. However, as described above, the same processing is possible even with three or more receiving antennas, and the extension is easy.
  • the radar apparatus that obtains each received signal obtained by receiving the pulse signal irradiated to the observation range with two or more antennas, and each SAR of each received signal.
  • the SAR image registered in the registration unit is compared with the SAR image aligned in the registration unit, and the signal calibrating unit corrects the amplitude and phase imbalance of each SAR image, and is corrected in the signal calibrating unit.
  • the azimuth decompression unit that performs azimuth decompression processing on the SAR image, and the azimuth decompression data that has been decompressed by the azimuth decompression unit as sub-apertures
  • the sub-aperture moving target detection unit calculates the speed in the range direction from the phase difference between the sub-apertures, and compares the calculated speed values.
  • the moving target is detected, so that the moving target can be detected easily and reliably.
  • the in-sub-aperture moving target detection unit calculates the speed in the range direction from the phase difference between the sub-apertures, and calculates the standard deviation value of the calculated speed. Since the moving target is detected by the threshold processing, the moving target detection process can be performed easily and reliably.
  • FIG. 9 is a functional block diagram illustrating a configuration for realizing the movement target detection process in the movement target detection apparatus according to the third embodiment.
  • the hardware configuration of the moving target detection apparatus in the third embodiment is the same as that in the second embodiment shown in FIG. That is, the configuration shown in FIG. 9 shows functional blocks realized by the processor 201 shown in FIG.
  • the moving target detection apparatus according to the third embodiment includes a difference image sub-aperture divided moving target detector 27 instead of the sub-aperture divided moving target detector 25 of the second embodiment. Further, a difference image calculation unit 26 for providing a difference image to the difference image sub-aperture division type moving target detection unit 27 is provided.
  • the difference image calculation unit 26 is configured to perform a clutter suppression process on each SAR image corrected by the signal calibration unit 23 to calculate a difference image of the SAR image. Since the SAR image generation unit 21, the registration unit 22, and the signal calibration unit 23 are the same as those in the first and second embodiments, description thereof is omitted here.
  • FIG. 10 is a configuration diagram of the difference image sub-aperture division type moving target detection unit 27.
  • the difference image sub-aperture division type movement target detection unit 27 includes a difference image decompression unit 271, a sub-aperture division unit 252, a difference image sub-aperture compression unit 272, a difference image sub-aperture phase difference calculation unit 273, and movement within the difference image sub-aperture.
  • a target detection unit 274 is provided.
  • the difference image decompressing unit 271 is a processing unit that performs azimuth decompression processing on the difference image calculated by the difference image calculating unit 26.
  • the sub-aperture dividing unit 252 is a processing unit that divides the difference image that has been subjected to azimuth compression by the difference image decompressing unit 271 into sub-apertures, and is similar to the sub-aperture dividing unit 252 of the second embodiment.
  • the difference image sub-aperture compression unit 272 is a processing unit that azimuth-compresses the difference image of each sub-aperture divided by the sub-aperture division unit 252 again.
  • the difference image sub-aperture phase difference calculation unit 273 is a processing unit that calculates the phase difference between the difference images of the sub-apertures that have been azimuth-compressed by the difference image sub-aperture compression unit 272.
  • the difference image sub-aperture movement target detection unit 274 is a processing unit that detects the movement target by comparing the phase differences of the sub-apertures calculated by the difference image sub-aperture phase difference calculation unit 273.
  • Embodiment 3 the movement target detection process of Embodiment 3 is demonstrated. Since this process is known as a SAR-DPCA (Displaced Phase Center Antenna) process, as described in Non-Patent Document 2, for example, description thereof is omitted here.
  • SAR-DPCA Dislaced Phase Center Antenna
  • the difference image ⁇ z (m ⁇ , n ⁇ ) obtained by the difference image calculation unit 26 is suppressed because a signal having a high signal-to-noise ratio is not easily influenced by phase noise.
  • the target signal having a low signal-to-noise ratio affected by the moving target and the phase noise remains without being suppressed.
  • the difference image decompression unit 271 compresses the difference image ⁇ z (m ⁇ , n ⁇ ) obtained by the difference image calculation unit 26 by the SAR image generation unit 21 in the same manner as the azimuth decompression unit 251 in the second embodiment. Uncompress azimuth compression and return to the state before azimuth compression.
  • the signal after azimuth decompression output from the differential image decompression unit 271 is expressed by the following equation.
  • the sub-aperture dividing unit 252 uses the hit corresponding to the sub-aperture from the signal ⁇ s (m ⁇ , n ⁇ ) that has been decompressed in the azimuth direction by the differential image decompressing unit 271. Extract number data.
  • the difference image sub-aperture compression unit 272 applies azimuth compression processing again to the signal for each sub-aperture decompressed in the azimuth direction, and compresses the signal in the azimuth direction.
  • the signal after azimuth compression of the difference image for each sub-aperture is expressed by the following equation.
  • phase unwrapping is solved.
  • the phase difference data of each sub-aperture obtained by the difference image sub-aperture phase difference calculation unit 273 is output to the difference image sub-aperture movement target detection unit 274.
  • the difference image sub-aperture moving target detection unit 274 can detect the moving target by extracting the pixel where the moving target exists from the phase difference for each sub-aperture.
  • Embodiment 3 it has been described that the number of SAR antennas to be received is two or more. However, as described above, the same processing is possible even with three or more reception antennas, and the expansion is easy.
  • the radar apparatus that obtains each received signal obtained by receiving the pulse signal irradiated to the observation range with two or more antennas, and each SAR of each received signal.
  • the SAR image registered in the registration unit is compared with the SAR image aligned in the registration unit, and the signal calibrating unit corrects the amplitude and phase imbalance of each SAR image, and is corrected in the signal calibrating unit.
  • a difference image calculation unit that performs a clutter suppression process on each SAR image to calculate a difference image of the SAR image
  • a difference image calculation unit A difference image decompression unit that performs azimuth decompression processing on the difference image, a sub-aperture division unit that divides the difference image that has been subjected to azimuth compression by the difference image decompression unit into sub-apertures, and each sub-aperture divided by the sub-aperture division unit
  • a difference image sub-aperture compression unit that azimuth-compresses the difference image again, a difference image sub-aperture phase difference calculation unit that calculates a phase difference between the difference images of the sub-aperture compressed by the difference image sub-aperture compression unit, and It has a difference image sub-aperture moving target detection unit that detects a moving target by comparing the phase difference of each sub-aperture calculated by the difference image sub-aperture phase difference calculation unit.
  • Moving target detection performance without detecting a stationary target that was erroneously detected as a moving target as a moving target It is possible to improve.
  • a moving target signal or a stationary target signal with a low signal-to-noise ratio is buried in a stationary target signal with a high signal-to-noise ratio, and detection accuracy is reduced. Therefore, the detection accuracy of the moving target can be improved.
  • FIG. 11 is a functional block diagram illustrating a configuration for realizing the movement target detection process in the movement target detection device according to the fourth embodiment.
  • the hardware configuration of the moving target detection apparatus in the fourth embodiment is the same as that of the second embodiment shown in FIG. That is, the configuration shown in FIG. 11 shows functional blocks realized by the processor 201 shown in FIG.
  • the moving target detection device according to the fourth embodiment moves between the difference image calculation unit 26 and the difference image sub-aperture divided type movement target detection unit 27.
  • a target rough detection unit 28 and a moving target peripheral region extraction unit 29 are provided.
  • the moving target rough detection unit 28 is a processing unit that extracts moving target candidates.
  • the movement target peripheral region extraction unit 29 is a processing unit that cuts out the signal periphery detected by the movement target rough detection unit 28.
  • the other configuration is the same as the configuration shown in FIG. 9, and therefore, the corresponding parts are denoted by the same reference numerals and description thereof is omitted.
  • the movement target rough detection unit 28 calculates the output power from the two difference images represented by the equation (26) calculated by the difference image calculation unit 26 as in the following equation.
  • the output power P (m ⁇ , n ⁇ ) shown in the above equation (30) is an output signal as a result of suppressing the stationary target signal.
  • the main residual component is a moving target 300 or a stationary target in which a phase difference is caused by phase noise having a low signal-to-noise ratio. For this reason, detection processing such as CFAR (Constant False Alarm Rate) processing or threshold processing is applied to the output power P (m ⁇ , n ⁇ ), and candidate pixels that are considered to be moving target signals are applied. It is possible to detect.
  • the movement target detection method in the movement target rough detection unit 28 is not limited to the above method, and any method can be used as long as it can extract pixels that are candidates for the movement target.
  • the movement target peripheral area extraction unit 29 cuts out the signal of the surrounding pixels extracted as the movement target signal in the movement target rough detection unit 28.
  • the pixel number extracted by the movement target rough detection unit 28 is assumed to be (m t , n t ).
  • the movement target peripheral area extraction unit 29 cuts out pixels around the movement target as in the following equation. Note that L is a range to be cut out. Other operations are the same as those in the third embodiment, and a description thereof is omitted here.
  • the moving target rough detection unit that extracts moving target candidates is provided, and the differential image decompression unit uses the signal detected by the moving target rough detection unit. Since processing is performed only for the third embodiment, in addition to the effect of the third embodiment, there is an effect that the processing speed can be increased.
  • the moving target peripheral region extraction unit that extracts the periphery of the signal detected by the moving target rough detection unit
  • the differential image decompression unit is a moving target peripheral region extraction unit. Since the processing is performed only on the extracted signal, the moving target detection processing can be speeded up.
  • the moving target detection device relates to a configuration for detecting a moving target signal from signals received by a plurality of antenna apertures, and is suitable for detecting a moving target in a synthetic aperture radar. Yes.

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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 une unité de génération d'image SAR (21) qui génère des images SAR pour un dispositif radar (10). Une unité d'enregistrement (22) aligne chaque image SAR à l'aide d'informations de vitesse pour une plate-forme mesurée par une unité de mesure de mouvement (30). Une unité d'étalonnage de signal (23) compare les images SAR et corrige un déséquilibre d'amplitude et de phase dans les images SAR. Une unité de détection de cible mobile (24) calcule les différences de phase entre les images SAR corrigées par l'unité d'étalonnage de signal (23) et détecte une cible mobile par comparaison de ces différences de phase.
PCT/JP2016/057787 2016-03-11 2016-03-11 Dispositif de détection de cible mobile WO2017154205A1 (fr)

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JP2021513653A (ja) * 2018-02-12 2021-05-27 テクノロギアン トゥトキムスケスクス ヴェーテーテー オイＴｅｋｎｏｌｏｇｉａｎ Ｔｕｔｋｉｍｕｓｋｅｓｋｕｓ Ｖｔｔ Ｏｙ マルチチャネルレーダによる生活施設の監視
TWI766507B (zh) * 2020-12-25 2022-06-01 維波科技有限公司 雷達回波訊號模擬系統
KR20230088103A (ko) * 2021-12-10 2023-06-19 국방과학연구소 압축센싱 기반 모노스태틱 레이다에 의한 근거리 비디오 sar 영상 생성 장치 및 방법
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US20230305129A1 (en) * 2022-03-24 2023-09-28 Ramesh Annavajjala Object Detection with Confidence Levels Using Compressed Radar Measurements

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