JPH11281739A - Radar signal processing system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an SAR image in a plurality of modes by using a single signal processing hardware. SOLUTION: A mode switching part 15 wherein process switching signal is outputted with a mode signal 14 as an input, and a signal processing part wherein, selected by a mode switching part output data, signal processing is performed for the output data of an A/D conversion part 2 for obtaining an image data through a normal SAR processing part 9, a PPI processing part 10, a high-resolution SAR processing part 11, an ISAR processing part 12, or a wide-area SAR processing part 13, are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a radar signal processing apparatus for acquiring image data using a synthetic aperture radar.

[0002]

2. Description of the Related Art FIG.
ne Radar Remote Sensing: A
applications And Technique
s "p140, Charles Elachi, IEEE
FIG. 3 is a block diagram illustrating a configuration of a conventional image radar signal processing device illustrated in E PRESS. In FIG. 10, 1 is the data received by the receiver, 2 is an A / D converter for converting this analog signal into digital, and 3 is the data of the output data of this A / D converter for the frequency component in the azimuth direction. The presum section 4 that applies a low-pass filter that passes only valid frequencies, performs frequency conversion on the output of this presum section by FFT, and multiplies the same by frequency-converted reference signals.
5 is a corner turn unit that rearranges data arranged in the range direction in the azimuth direction for subsequent processing, and 6 is a frequency transform by FFT for each range data in the azimuth direction. An azimuth compression unit for performing multiplication with a reference signal that has also been subjected to frequency conversion and then returning to time axis data by inverse FFT, a multi-look processing unit 7 for performing an integration process to reduce speckle noise, and a multi-look processing unit 8 A data display unit that performs conversion for displaying data on the output of the processing unit.

[0003]

The conventional synthetic aperture radar signal processing apparatus is configured as described above.
There is a problem that only SAR images of two modes can be obtained. Further, when another mode is required, hardware for the number of modes is required, and there is a problem that the hardware scale becomes large.

Further, the synthetic aperture radar has a condition that the target is fixed and the radar platform is moving, so that there is a problem that the image is blurred when the target moves.

Further, there is a problem that an image of a synthetic aperture radar cannot be obtained when focusing on a moving target.

In addition, there is a problem in that the moving target is not focused when it is imaged, and information on the moving target cannot be obtained.

Further, when the resolution is improved, there is a problem that the synthetic aperture time becomes longer and it takes time to obtain an image.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to obtain SAR images in a plurality of modes using one signal processing hardware.

[0009]

The radar signal processing apparatus according to the first invention has signal processing for performing a plurality of different processes by one signal processing unit.

Further, the radar signal processing apparatus according to the second invention detects a moving target from a normal SAR image when the moving target exists, and performs the ISAR processing only on the moving target.
This is to synthesize an ISAR image.

In the radar signal processing apparatus according to the third invention, when a moving target exists, only the moving target is ISAR
Processing is performed to synthesize an ISAR image with a normal SAR image.

A radar signal processing apparatus according to a fourth aspect of the present invention has a function of automatically focusing when imaging a moving target.

Further, the radar signal processing apparatus according to the fifth invention has a velocity vector detecting section for obtaining information on a moving target, such as velocity and traveling direction.

Further, the radar signal processing apparatus according to the sixth aspect of the present invention has a process of displaying a low-resolution image to a high-resolution image in stages when the image reproduction processing time is long.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIGS. 1 to 5 are diagrams for explaining Embodiment 1 of the present invention. Note that the same components as those in the related art are denoted by the same reference numerals, and description thereof is omitted. In FIG. 1, 14 is a mode signal, 1
Reference numeral 5 denotes a mode switching unit which outputs a processing switching signal by using the mode signal 14 as an input, and 16 denotes a mode selected by the output data of the mode switching unit 14 and performs signal processing on the output data of the A / D conversion unit to obtain image data. It is a signal processing unit. Also, 9, 10, 11, 1 in the signal processing unit 16
Reference numerals 2 and 13 denote ordinary SAR processing units, PPI processing units, high-resolution SAR processing units, ISAR processing units, and wide area SAs, respectively.
This is an R processing unit.

In FIG. 2, reference numeral 17 denotes an amplitude detecting section, and 18 denotes an integrating section. In FIG. 3, reference numeral 19 denotes a motion compensation unit, reference numeral 20 denotes a polar format processing unit, and reference numeral 21 denotes an FFT unit. In FIG. 4, reference numeral 23 denotes a range migration correction unit;
Is a phase correction unit.

The operation of the first embodiment will be described below with reference to FIGS. In FIG. 1, received data 1 is analog video from a receiver. The A / D converter 2 converts the received data 1 into a digital signal. The mode signal 14 is a signal for selecting a process to be performed in the signal processing. The mode switching unit 15 outputs a processing switching signal in response to the mode signal 14. The signal processing unit 16 selects one of the processes 9 to 13 according to the output of the mode switching unit 15. Then, the image data from the signal processing unit 16 is displayed on the screen by the data display unit 8.

The PPI processing section 10 will be described with reference to FIG. The output of the mode switching unit 15 is subjected to range compression by the range compression unit 4, and this output is complex data, and the amplitude is obtained by the amplitude detection unit 17. In order to increase the signal-to-noise ratio so as to make the display easier to see, the integration section 16 performs pulse-to-pulse integration, and the data display section 8 displays data.

The high-resolution SAR processing section 11 will be described with reference to FIG. Normal SAR for high resolution SAR
Since the data processing amount is larger than the processing, the mode switching unit 15
Is filtered in the azimuth direction by the presuming unit 3 to extract only a signal in a desired band and reduce the data rate. Thereafter, the motion compensation unit 19 performs distance correction based on the motion data of the radar platform so that the distance from the center of the image is constant. The polar format processing unit 20 uses SAR on the polar coordinates of the frequency axis and the azimuth angle axis.
The processing is performed, the image is returned to the spatial axis by the FFT unit 21, and integration is performed by the multi-look processing 7 to improve the signal-to-noise ratio, thereby obtaining a two-dimensional image in the range direction and the azimuth direction.

The ISAR processing unit 12 will be described with reference to FIG. The ISAR process is the same for the range compression unit 4 and the motion compensation unit 19 as described above. The range migration unit 23 corrects the range shift amount of each point of the image due to the movement of the radar platform, and the phase compensation unit 24 corrects the phase shift of each point of the image due to the movement of the radar platform. Finally, FFT is performed by the FFT unit 21 to obtain an ISAR image.

The wide area SAR processing section 13 will be described with reference to FIG. Although the image area is large in the wide area SAR processing,
Since the resolution is lower than that of normal SAR processing, image data is obtained by performing FFT in the FFT unit 21 instead of azimuth compression, that is, applying a matched filter.

Embodiment 2 FIG. FIG. 6 is a view for explaining Embodiment 2 of the present invention. Note that the same components as those in the related art and the above description have the same reference numerals and description thereof will be omitted. 27 is an isolated reflection point detection unit, and 22 is a process switching unit.

Hereinafter, the operation of the second embodiment will be described with reference to FIG. In FIG. 6, the signal processing unit 16 switches between the high-resolution SAR processing unit 11 and the ISAR processing unit 12. The output data of the mode switching unit 15 is processed by the high-resolution SAR processing unit 11,
An isolated reflection point detection unit 27 detects an isolated reflection point from the output. If no isolated reflection point is detected, the process switching unit 22 performs multi-look processing on the output data of the FFT unit 21 and outputs the data on the data display unit 8. On the other hand, when an isolated reflection point is detected, the process switching unit 22 switches to the ISAR process 12 because a moving target exists in the image and that portion is blurred. Two-dimensional data centered on the position of the isolated reflection point is cut out by the data cutout unit 25, and the output data of the mode switching unit 15 is fixed by the motion compensation unit 19 from the motion data of the radar platform to the center of the image. The distance is corrected so that The range migration correction unit 23 corrects the distance and the phase correction unit 24 corrects the phase of the output data of the motion compensation unit. The FFT unit 21 performs FFT on the output data of the phase correction unit 24, and the data processing unit 8 displays image data.

Embodiment 3 FIG. FIG. 7 is a view for explaining Embodiment 3 of the present invention. Note that the same components as those in the related art and the above description have the same reference numerals and description thereof will be omitted. Reference numeral 26 denotes an image synthesizing unit that superimposes image data.

Hereinafter, the operation of the third embodiment will be described with reference to FIG. In FIG. 7, a high-resolution SAR processing unit 11 and an ISAR processing unit 12 are simultaneously performed by a signal processing unit 16. The output data of the mode switching unit 15 is processed by the high-resolution SAR processing unit 11, and the isolated reflection point detection unit 27 detects an isolated reflection point from its output. When an isolated reflection point is detected, a moving target exists in the image, and that part is blurred.
The R processing 12 is performed. Two-dimensional data centered on the position of the isolated reflection point is cut out by the data cutout unit 25, and the output data of the mode switching unit 15 is fixed by the motion compensation unit 19 from the motion data of the radar platform to the center of the image. The distance is corrected so that The range migration correction unit 23 corrects the distance and the phase correction unit 24 corrects the phase of the output data of the motion compensation unit. The output data of the phase correction unit 24 is F
The FFT is performed by the FT unit 21 to obtain image data. The image data is superimposed on the image data of the FFT unit 21 by the image synthesizing unit 26 while being aligned, and the data processing unit 8 displays the image data.

Embodiment 4 FIG. 8 is a view for explaining Embodiment 4 of the present invention. Note that the same components as those in the related art and the above description have the same reference numerals and description thereof will be omitted. 28 is a frequency history calculation unit.

The operation of the fourth embodiment will be described below with reference to FIG. In FIG.
The isolated reflection point detection unit 26 performs isolated point detection on the output of the range migration correction unit 23 of the AR processing unit 12. Focusing on this isolated point, the frequency history calculation unit 28 calculates a change in frequency. The phase correction unit 24 converts the frequency change into the phase change to correct the phase, and performs isolated reflection point detection again. By repeating the processing until the frequency history becomes a straight line and performing phase correction, an image with focus is obtained. Finally, FFT is performed by the FFT unit 21 to obtain moving target image data.

Embodiment 5 FIG. 9 is a view for explaining Embodiment 5 of the present invention. Note that the same components as those in the related art and the above description have the same reference numerals and description thereof will be omitted. 29 is a ship detection unit, 30 is a wake detection unit, and 31 is a speed vector estimation unit.

Hereinafter, the operation of the fifth embodiment will be described with reference to FIG. In the signal processing unit 16, first, the output data of the mode switching unit 15
The AR processing unit 9 performs a normal SAR process, and on the premise that the output data of the azimuth compression unit 6 is data at sea, the ship detection unit 29 detects a high-luminance part as a ship and obtains position information. . The wake detection unit 30 detects wakes extending in two directions from the position data, and the speed vector estimation unit 31 detects the course and speed of the ship.

Embodiment 6 FIG. The configuration of the sixth embodiment of the present invention is the same as that of FIG. 1 'is reception data obtained by dividing the synthetic aperture time.

The operation of the sixth embodiment will be described below with reference to FIG. The reception data 1 'is data obtained by dividing the synthetic aperture time into several stages and receiving the data for each division. The A / D converter 2 performs A / D conversion on the received data 1 ', and performs high-resolution SAR processing on the output of the mode switching unit 15. First, the data processing unit 8 displays the image obtained by the first division. Next, the high-resolution SAR processing unit 11 processes the received data obtained by the first division and the second division, and the obtained image is displayed by the data processing unit 8. In this way, the high-resolution SAR processing unit 11 performs processing using the data received so far for each division,
By performing the display, the image is displayed stepwise from an image having a low resolution to an image having a high resolution.

[0032]

According to the first aspect of the present invention, a plurality of different processes are performed by one signal processing unit, so that an image having a different resolution regardless of a target or terrain, a wide-area image, an image capturing characteristics of a signal, and the like can be obtained. There is an effect that image information can be obtained by one signal processing device.

Further, according to the second aspect, when a moving target exists, there is an effect that the moving target can be detected from a normal SAR image to obtain an ISAR image.

According to the third aspect of the present invention, when a moving target exists, only the moving target is subjected to the ISAR process, and the SAR image is synthesized with the normal SAR image so that the moving target does not become a blurred image. There is an effect that can be made.

Further, according to the fourth aspect, there is an effect that the phase correction can be automatically performed by obtaining the frequency history for the moving target.

Further, according to the fifth aspect, there is an effect that information such as the speed and the traveling direction can be obtained for the moving target.

Further, according to the sixth invention, when the image reproduction processing time is long, there is an effect that the display can be performed step by step from an image having a low resolution to an image having a high resolution.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a radar signal processing apparatus according to a first embodiment of the present invention.

FIG. 2 is a detailed configuration diagram of a signal processing unit in the first embodiment of the radar signal processing device according to the present invention;

FIG. 3 is a detailed configuration diagram of a signal processing unit in the first embodiment of the radar signal processing device according to the present invention;

FIG. 4 is a detailed configuration diagram of a signal processing unit in the first embodiment of the radar signal processing device according to the present invention; Also,
FIG. 14 is a diagram showing a configuration of a radar signal processing device according to a sixth embodiment of the present invention.

FIG. 5 is a detailed configuration diagram of a signal processing unit in the first embodiment of the radar signal processing device according to the present invention;

FIG. 6 is a diagram showing a configuration of a radar signal processing apparatus according to a second embodiment of the present invention.

FIG. 7 is a diagram showing a configuration of a radar signal processing device according to a third embodiment of the present invention.

FIG. 8 is a diagram showing a configuration of a radar signal processing device according to a fourth embodiment of the present invention.

FIG. 9 is a diagram showing a configuration of a radar signal processing apparatus according to a fifth embodiment of the present invention.

FIG. 10 is a diagram showing a configuration of a conventional radar signal processing device.

[Explanation of symbols]

1 received data, 2 A / D conversion section, 3 presum section,
4 range compression section, 5 corner turn section, 6 azimuth compression section, 7 multi-look processing section, 8 data processing section,
9 SAR processing unit, 10 PPI processing unit, 11 high-resolution SAR processing unit, 12 ISAR processing unit, 13 wide area S
AR processing unit, 14 mode signal, 15 mode switching unit, 1
6 signal processing unit, 17 amplitude detection unit, 18 integrator, 1
9 Motion compensation unit, 20 Polar format processing unit, 2
1 FFT section, 22 processing switching section, 23 range migration correction section, 24 phase correction section, 25 data cutout section, 26 image synthesis section, 27 isolated reflection point detection section, 28 frequency history calculation section, 29 ship detection section,
30 wake detector, 31 speed vector estimator.

Claims (6)

[Claims] 1. An A / D conversion unit for performing A / D conversion by receiving received data as input, and a SAR (Synthetic Ape)
true Radar) processing, PPI (Plan P)
a mode switching unit that outputs a processing switching signal by inputting a mode signal for selecting any one of the position indicator processing, the high-resolution SAR processing, the ISAR (inverted SAR) processing, and the wide area SAR processing, and the mode switching unit And performs signal processing on the output data of the A / D conversion unit, and performs any one of the SAR processing unit, the PPI processing unit, the high-resolution SAR processing unit, the ISAR processing unit, and the wide area SAR processing unit. A radar signal processing apparatus, comprising: a signal processing unit for performing image data to obtain image data; and a data display unit for displaying output data of the signal processing unit. 2. A signal processing section, comprising: a presum section for applying a presum filter to output data of a mode switching section; a range compression section for performing range compression on an output of the presum section; and a fluctuation in the output of the range compression section. A fluctuation compensating section for performing compensation, a polar format processing section for performing a polar format process on an output of the vibration compensating section, an FFT section for performing an FFT on an output of the polar format processing section, and a luminance value for an output of the FFT section. An isolated reflection point detection unit that detects high data, a processing switching unit that switches processing based on output data of the isolated reflection point detection unit, and an output of the processing switching unit that is SAR
In the case of processing, a multi-look processing unit that performs multi-look on the output data of the two-dimensional FFT unit, and when the output of the processing switching unit is an ISAR process, the output data of the mode switching unit at the position of the isolated reflection point A data cutout unit that cuts out data, a range compression unit that performs range compression on output data of the data cutout unit,
A motion compensator that corrects the momentum of the own machine for output data of the range compressor, a range migration corrector that corrects the distance for the output data of the motion compensator,
A phase correction unit that performs a phase correction on the output data of the range migration correction unit, an FFT unit that performs an FFT on the output data of the phase correction unit, and either the output data of the FFT unit or the output data of the multi-look processing unit 2. The radar signal processing device according to claim 1, further comprising a data display unit for displaying the data. 3. The signal processing section, wherein a presum section that applies a presum filter to output data of the mode switching section, a range compression section that performs range compression on an output of the presum section, and output data of the range compression section. A motion compensator that corrects the momentum of the own device, a polar format processor that performs polar format processing on output data of the motion compensator, and an FF that performs FFT on output data of the polar format processor
A T-section, an isolated reflection point detection section for detecting high-luminance data for the output data of the FFT section, and output data of the data switching section at the position of the isolated reflection point which is output data of the isolated reflection point detection section A data cutout unit that cuts out the data, a motion compensation unit that corrects the momentum of the own machine with respect to the output data of the range compression unit for the output data of the data cutout unit, and a range that corrects the distance for the output data of the motion compensation unit A migration correction section, a phase correction section for performing phase correction on output data of the range migration correction section, an FFT section for performing FFT on output data of the phase correction section, output data of the FFT section, and output of the FFT section. An image synthesizing unit for superimposing data, and data for displaying output data of the image synthesizing unit The radar signal processing apparatus according to claim 1, characterized in that comprising a radical 113. 4. The signal processing section, wherein: a range compression section for performing range compression on output data of the mode switching section; a motion compensation section for correcting a momentum of the own machine with respect to output data of the range compression section; A range migration correction unit that corrects the distance with respect to the output data of the compensation unit; an isolated reflection point detection unit that detects high-luminance data for the output data of the range migration correction unit or the output data of the phase correction unit; A frequency history calculation unit that calculates a change in frequency using output data of the point detection unit; a phase correction unit that performs phase correction using output data of the frequency history calculation unit; FFT section for performing FFT on focused data, and data table displaying output data of this FFT section The radar signal processing device according to claim 1, further comprising an indicating unit. 5. The signal processing section, wherein a presum section that applies a presum filter to output data of the mode switching section, a range compression section that performs range compression on an output of the presum section, and output data of the range compression section. A corner turn section for performing a corner turn, an azimuth compression section for performing azimuth compression on output data of the corner turn section, a ship detection section for detecting a ship with respect to the output data of the azimuth compression section, and output data of the ship detection section. A wake detector that detects wakes extending in two directions from, and the route of the ship from the output data of the wake detector
2. The radar signal processing device according to claim 1, further comprising a speed vector estimating unit for detecting a speed. 6. An A / D converter which divides a synthetic aperture time into several stages and performs A / D conversion on data received so far for each division.
A D / D converter, a presum unit that applies a presum filter to output data of the A / D converter for each stage, a motion compensation unit that performs motion compensation for output data of the presum unit for each stage, The polar format processing unit that performs polar format processing on the output of the motion compensation unit, the FFT unit that performs two-dimensional FFT on the output of the polar format processing unit for each stage, and the output of the two-dimensional FFT unit for each stage 2. The radar signal processing device according to claim 1, comprising a multi-look processing unit for performing a multi-look process, and a data display unit for displaying output data of the multi-look processing unit for each stage.