JPH11231050A - Synthetic aperture radar signal processing system - Google Patents

Abstract

[PROBLEMS] To provide a synthetic aperture radar signal processing system capable of eliminating a memory bottleneck and a bus bottleneck occurring when executing range cover correction in an azimuth compression processor. SOLUTION: In parallel with the compression processing in the azimuth direction in a plurality of azimuth compression processors 2, an azimuth compression processor 2 connects the adjacent azimuth compression processors 2 via a data transfer path 4 for the azimuth compression processor. By transferring intermediate processing data of the compression processor 2 to the adjacent azimuth compression processor 2, a memory bottleneck and a bus bottleneck caused in range coverage correction can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synthetic aperture radar mounted on a satellite or an aircraft.
rture Radar (hereinafter referred to as SAR), a digital processing system (hereinafter referred to as an SAR signal processing system) for reproducing images that can be understood by humans.
).

[0002]

2. Description of the Related Art In the field of remote sensing using artificial satellites or aircraft, SAR is well known as a sensor capable of imaging the surface of the earth with high resolution without being affected by weather such as clouds.

[0003] The image data (hereinafter referred to as observation data) received by the SAR has a two-dimensional spread in the range direction and the azimuth direction. A process of reproducing an image (hereinafter referred to as an image reproduction process) is required.

First, a basic SAR image reproduction process will be described with reference to FIGS. FIG. 7 is a diagram showing the flow of a basic SAR image reproducing process, and FIG. 8 is a schematic diagram showing the concept of range coverage correction. In FIG. 7, the SAR image reproduction process compresses observation data in the range direction (hereinafter, referred to as range compression), and then compresses the observation data in the azimuth direction (hereinafter, referred to as azimuth compression) to generate a reproduced image. In digital processing, the compression processing is performed by convolution of point image pattern data for each line of observation data. However, if the convolution processing is executed as it is, a huge processing time will be required. Therefore, fast Fourier transform (hereinafter, referred to as FFT), complex multiplication, fast inverse Fourier transform
(Hereinafter, referred to as IFFT) is generally used to increase the speed.

Next, the range cover correction will be described with reference to FIG. To improve the quality of the playback image,
Processing such as range coverage correction is indispensable. Range coverage correction is for correcting blur caused by a change in the distance (range) between the SAR and the imaging target.
After performing FFT processing in the frequency space in the middle of compression in the azimuth direction, that is, after performing FFT processing in the azimuth direction, the same range data distributed on the quadratic curve is resampled (interpolated and picked up) on a straight line.

Hereinafter, a conventional SAR signal processing system for performing the SAR image reproduction processing as described above will be described.

First, as a conventional example, Japanese Patent Laid-Open Publication No.
The SAR signal processing system described in Japanese Patent Publication No. 87 will be described. FIG. 13 is a block diagram showing a configuration of a conventional SAR signal processing system described in the publication. In FIG. 13, 1 is a range compression processor for performing range compression, 13 is an azimuth compression processor for performing azimuth compression, and 3 is data for transferring processing data between the plurality of range compression processors 1 and the plurality of azimuth compression processors 13. It is a transfer path.

In the above-mentioned conventional SAR signal processing system,
The observation data is divided in the azimuth direction, the range compression is performed in parallel by the plurality of range compression processors 1, the data after the range compression is divided in the range direction, and the azimuth compression is processed in parallel by the plurality of azimuth compression processors 13. It is configured as follows.

Next, the operation of the SAR signal processing system in the above-mentioned conventional example will be described with reference to FIGS. FIG. 9 is a diagram showing a data structure of SAR observation data, FIG. 10 is a diagram showing a state in which observation data is divided and input to N range compression processors in the azimuth direction, and FIG.
FIG. 1 is a diagram showing a state in which data after range compression is divided and input to M azimuth compression processors in the range direction, and FIG. 12 is a diagram in which azimuth compression is divided into M data in the range direction and parallelized by M azimuth compression processors. FIG. 9 is a diagram showing a problem of range coverage correction that occurs when processing is performed in the first embodiment.

The observation data is composed of n data in the range direction and m data in the azimuth direction as shown in FIG. Such observation data is divided into N pieces in the azimuth direction as shown in FIG. 10, and each is input to each of the N range compression processors 1. That is, each range compression processor 1 receives n data in the range direction and (m / N) data in the azimuth direction.

[0011] Each range compression processor 1 calculates (n × (m
/ N)) data is input, data is taken out line by line in the range direction, that is, n data are taken out and range compression processing is performed. That is, FFT, complex multiplication, and IFFT are performed on the extracted n data. By repeating this (m / N) times, range compression is performed on all input data.

Next, each range compression processor 1 converts the data after range compression into M azimuth compression processors 13.
Then, the data is transferred via the data transfer path 3. At this time, FIG.
As shown in FIG. 1, the data is transferred so as to be divided into M in the range direction. That is, each azimuth compression processor 13 receives (n / M) data in the range direction and m data in the azimuth direction.

Each azimuth compression processor 13 has a function of ((n
When (/ M) × m) pieces of data are input, data is extracted for each line in the azimuth direction, that is, m pieces of data are extracted and azimuth compression processing is performed. That is,
FFT, range coverage correction, complex multiplication, and IFFT are performed on the extracted m pieces of data. This is (n /
By repeating M) times, azimuth compression is performed on all the input data.

However, as described above, when the data after range compression is divided into M data in the range direction, and the azimuth compression is processed in parallel by the M azimuth compression processors 13, the processing of the range coverage correction is large. It becomes a problem.

In the range coverage correction, as described above with reference to FIG. 8, after performing FFT processing in the azimuth direction, the same range data distributed on a quadratic curve is resampled (interpolated and picked up) on a straight line. However, the data is stored in a plurality of azimuth compression processors 13 as shown in FIG.
Will be straddling. As a method for solving this, for example, there is a method disclosed in Japanese Patent Application Laid-Open No. 58-191979.

Next, as a conventional example for solving the problem of the range coverage correction, a SAR signal processing system described in Japanese Patent Application Laid-Open No. 58-191979 and shown in FIG. 14 will be described. FIG. 14 is a block diagram showing a configuration of a conventional synthetic aperture radar signal processing system. In FIG. 14, reference numeral 13 denotes an azimuth compression processor for performing azimuth compression, and reference numeral 14 denotes a shared memory which is accessible from all azimuth compression processors 13 and stores data after FFT processed by each azimuth compression processor 13.

In such a conventional SAR signal processing system, the FF processed by each azimuth compression processor 13
The data after T is stored in the shared memory 14. Next, when range coverage correction is performed by each azimuth compression processor 13, the process is executed with reference to the data after FFT stored in the shared memory 14.

Next, the operation of the conventional SAR signal processing system shown therein will be described with reference to FIG. When ((n / M) × m) data is input, each azimuth compression processor 13 extracts data for each line in the azimuth direction, that is, extracts m data, performs FFT, Data after FFT is shared memory 1
4 at a predetermined position. By repeating this (n / M) times, FFT is performed on all the input data, and all the results are stored in a predetermined position of the shared memory 14.

Next, each azimuth compression processor 13
The desired data is read from the shared memory 14 in accordance with the quadratic curve, and is resampled on a straight line to execute range coverage correction. Complex multiplication, IFFT
To complete the azimuth compression.

Further, as a conventional example for solving the problem of the range coverage correction, a SAR signal processing system described in Japanese Patent Application Laid-Open No. 58-191979 and shown in FIG. 15 will be described. FIG. 15 is a block diagram showing a configuration of a conventional synthetic aperture radar signal processing system. In FIG. 15, reference numeral 13 denotes an azimuth compression processor for performing azimuth compression, reference numeral 15 denotes a range coverage correction specific memory for storing data after FFT, and reference numeral 16 denotes a range coverage correction specific memory in another azimuth compression processor 13 for storing the FFT data. This is a shared bus for writing.

That is, in the SAR signal processing system shown in FIG. 15, the data after FFT processed by each azimuth compression processor 13 is stored in a range coverage correction specific memory 15 in another azimuth compression processor 13.
When the data is transferred and stored using the shared bus 16 and then the range coverage correction is performed by each azimuth compression processor 13, the data after FFT stored in the range coverage correction specific memory 15 in each azimuth compression processor 13 And execute the process.

Next, the operation of the conventional SAR signal processing system shown therein will be described with reference to FIG. When ((n / M) × m) data is input, each azimuth compression processor 13 extracts data for each line in the azimuth direction, that is, extracts m data, performs FFT, The data after FFT is shared bus 16
Is stored in a predetermined position of the range coverage correction specific memory 15 in another azimuth compression processor 13.
By repeating this (n / M) times, the FFT is performed on all the input data, and the result is stored at a predetermined position in the range coverage correction specific memory 15 in each azimuth compression processor 13.

Next, each azimuth compression processor 13
According to the quadratic curve, desired data is read from the range-coverage correction unique memory 15, and is resampled on a straight line to execute range-coverage correction. This data is subjected to complex multiplication and IFFT to complete azimuth compression.

[0024]

However, the SAR signal processing system shown in FIG. 14 employs a system having a shared memory 14 for performing range coverage correction. However, since only one processor can access the shared memory 14 at a time, there is a problem that a memory bottleneck occurs.

Therefore, M azimuth compression processors 1
3 must be able to access the shared memory 14 at the same time. For this reason, there is a problem that the circuit scale becomes large.

As shown in the SAR signal processing system shown in FIG. 15, when the azimuth compression-specific memory 15 is provided in each azimuth compression processor 13 for performing the range coverage correction, However, since the data after FFT is stored in the range coverage correction specific memory 15 in another azimuth compression processor 13 using the shared bus 16, there is a problem that a bus neck occurs.

A plurality of azimuth compression processors 13
Has to store the data after the FFT in the unique memory 15 for range coverage correction in the same azimuth compression processor 13, which causes a problem of a memory bottleneck.

The present invention has been made to solve the above-mentioned conventional problems, and has as its object to eliminate a memory bottleneck and a bus bottleneck caused by range coverage correction in an azimuth compression processor.

[0029]

According to a first aspect of the present invention, there is provided a SAR signal processing system comprising: range compression processing means for dividing imaging data by a synthetic aperture radar in an azimuth direction and performing compression processing in a range direction in parallel; Azimuth compression processing means for dividing the data compressed in the range direction by the range compression processing means in the range direction and performing compression processing in the azimuth direction in parallel; and the azimuth compression processing means connected to the azimuth compression processing means. And a data transfer processing means for transferring an intermediate processing result to an adjacent azimuth compression processing means independently and in parallel.

According to a second aspect of the present invention, in the SAR signal processing system, the data transfer processing unit transmits an intermediate processing result of the own azimuth compression processing unit to an adjacent azimuth compression processing unit; Data receiving means for receiving an intermediate processing result of an adjacent azimuth compression processing means in parallel with the transmission of the intermediate processing result.

According to a third aspect of the present invention, in the SAR signal processing system, the data transfer processing means transmits an intermediate processing result transmitted from an adjacent azimuth compression processing means to another adjacent azimuth compression processing means. This is provided with transfer means for transferring.

According to a fourth aspect of the present invention, in the SAR signal processing system, the data transfer processing means includes information storage means for storing information for specifying data to be transferred, and refers to the information storage means. Thus, the desired data to be transferred is transmitted to the adjacent azimuth compression processing means.

According to a fifth aspect of the present invention, in the SAR signal processing system, the information storage means stores an address of data to be transferred stored in a means for storing a processing result by the azimuth compression processing means, The data transfer processing means reads out data to be transferred with reference to the address and transmits the data to an adjacent azimuth compression processing means.

According to a sixth aspect of the present invention, in the SAR signal processing system, the information storage means includes a base address, an offset, and a base address of data to be transferred stored in a means for storing a processing result of the azimuth compression processing means. And the data transfer processing means reads data to be transferred from the address calculated from the base address and the offset stored in the information storage means, and transmits the data to the adjacent azimuth compression processing means. is there.

According to a seventh aspect of the present invention, the SAR signal processing system is connected to the information storage means, calculates information for specifying data to be transferred to an adjacent azimuth compression processing means, and calculates a calculation result as the information. A control means for storing the data in the storage means is provided to specify and read out the data to be transferred from the calculation result, and to transmit the data to an adjacent azimuth compression processing means.

[0036]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the accompanying drawings and FIGS. FIG. 1 is a block diagram showing a configuration of a synthetic aperture radar signal processing system according to Embodiment 1 of the present invention. FIG. 2 is a block diagram showing a configuration of a synthetic aperture radar signal processing system according to Embodiment 2 of the present invention. FIG. 4 is a block diagram illustrating a configuration of a synthetic aperture radar signal processing system according to Embodiment 3 of the present invention. FIG. 4 is a block diagram illustrating a configuration of a synthetic aperture radar signal processing system according to Embodiment 4 of the present invention.
FIG. 6 is a block diagram showing a configuration of a synthetic aperture radar signal processing system according to Embodiment 7 of the present invention. FIG. 6 shows a range cover when azimuth compression is divided into M in the range direction and processed in parallel by M azimuth compression processors. FIG. 11 is a diagram illustrating a state where data necessary for correction exists in three azimuth compression processors.

Embodiment 1 First, the configuration of the SAR signal processing system according to the first embodiment of the present invention will be described with reference to FIG. In FIG. 1, 1 is a range compression processor as range compression processing means for performing range compression, 2 is an azimuth compression processor as azimuth compression processing means for performing azimuth compression, 3 is a plurality of range compression processors 1 and a plurality of azimuth compression processors 2, a data transfer path for transferring processing data between the azimuth compression processors 2; a data transfer path for an azimuth compression processor 4 for transferring processing data between adjacent azimuth compression processors 2; A data transfer processor serving as a data transfer processing means for transferring an intermediate processing result of the azimuth compression processor 2 to an adjacent azimuth compression processor 2 via an azimuth compression processor data transfer path 4; Buffer memory for storing the result of performing Is a buffer memory for storing the data transferred by the data transfer processor 5.

In the SAR signal processing system according to the present embodiment, the adjacent azimuth compression processors 2 are connected by the azimuth compression processor data transfer path 4, and in parallel with the azimuth compression processing in the azimuth compression processor 2, The data transfer processor 5 is configured to transfer the intermediate processing data of the azimuth compression processor 2 only to the adjacent azimuth compression processor 2.

Next, the operation of the SAR signal processing system according to the first embodiment of the present invention will be described mainly with reference to FIG. Observed data is n in the range direction as shown in FIG.
And m data in the azimuth direction. Such observation data is divided into N pieces in the azimuth direction as shown in FIG. That is, each range compression processor 1 receives n data in the range direction and (m / N) data in the azimuth direction.

Each range compression processor 1 calculates (n × (m
/ N)) data is input, data is taken out line by line in the range direction, that is, n data are taken out and range compression processing is performed. That is, FFT, complex multiplication, and IFFT are performed on the extracted n data. By repeating this (m / N) times, range compression is performed on all input data.

Next, each range compression processor 1 transfers the data after range compression to M azimuth compression processors 2 via the data transfer path 3. At this time, FIG.
As shown in (1), the data is transferred so as to be divided into M in the range direction. That is, each azimuth compression processor 2 includes:
(N / M) pieces in the range direction and m in the azimuth direction
Data is input.

Each azimuth compression processor 2 calculates ((n /
When M) × m) pieces of data are input, data is fetched line by line in the azimuth direction, that is, m pieces of data are fetched, and azimuth compression processing is started. That is, FFT, range coverage correction, complex multiplication, and IFFT are performed on the extracted m pieces of data.

Each azimuth compression processor 2 starts FFT processing, ie, azimuth direction FFT, for one line in the azimuth direction taken out, ie, m pieces of data.

When each azimuth compression processor 2 finishes the FFT processing, it stores the result in a predetermined position of the buffer memory 6 and instructs the data transfer processor 5 to transfer the data. And the next one in the azimuth direction
Line data, that is, m pieces of data, are taken out, and FFT in the azimuth direction is started.

The data transfer processor 5 performs an FFT for one line in the next azimuth direction of the azimuth compression processor 2.
In parallel with the processing, one line of data in the azimuth direction after FFT, that is, m pieces of data, which is first processed in the azimuth compression processor 2 and stored in the buffer memory 6, is taken out and transferred to the azimuth compression processor. The data is stored in a predetermined location of the buffer memory 7 in the adjacent azimuth compression processor 2 via the path 4.

Here, since the data required when each azimuth compression processor 2 processes the range coverage correction exists in the adjacent azimuth compression processor 2 as shown in FIG. The data transfer processor 5 in the compression processor 2 stores the FF in the buffer memory 7 in the first azimuth compression processor 2.
T, and the data transfer processor 5 in the third azimuth compression processor 2 transfers the data after FFT to the buffer memory 7 in the second azimuth compression processor 2. . . Mth azimuth compression processor 2
The data transfer processor 5 transfers the data after FFT to the buffer memory 7 in the (M-1) th azimuth compression processor 2.

On the other hand, the azimuth compression processor data transfer path 4 is prepared for data transfer between adjacent azimuth compression processors 2, so that the data transfer by the plurality of data transfer processors 5 is independent of each other. And can be done simultaneously.

Thus, each azimuth compression processor 2
Is to perform the FFT in the azimuth direction on the data of (n / M) lines in the azimuth direction by repeating the above processing (n / M) times, The data after FFT processed by the own azimuth compression processor 2 is stored in the buffer memory 7, and the data after FFT processed by the adjacent azimuth compression processor 2 is stored in the buffer memory 7.

Next, each azimuth compression processor 2 processes the range coverage correction by referring to the buffer memory 6 and the buffer memory 7, and performs complex multiplication and IFFT on the result, thereby performing azimuth compression. Complete the process.

Embodiment 2 First, the configuration of the SAR signal processing system according to the second embodiment of the present invention will be described with reference to FIG. In FIG. 2, 1 is a range compression processor for performing range compression, 2 is an azimuth compression processor for performing azimuth compression, and 3 is data for transferring processing data between the plurality of range compression processors 1 and the plurality of azimuth compression processors 2. A transfer path 4 is a data transfer path for an azimuth compression processor for transferring data processed by an adjacent azimuth compression processor 2, and a transmission path 4 is an intermediate processing result of the azimuth compression processor 2 in parallel with the processing of the azimuth compression processor 2. A data transfer processor for transferring data to an adjacent azimuth compression processor 2 via an azimuth compression processor data transfer path 4, a buffer memory 6 for storing the result of performing an FFT in the azimuth direction, and a data transfer processor 7 for transferring data. Buffer memory for storing the data A transmission mechanism as data transmission means for transmitting the post-FFT data stored in the buffer memory 6 to the adjacent azimuth compression processor 2. The transmission mechanism 9 receives the post-FFT data transmitted from the adjacent azimuth compression processor 2 and stores the data in a buffer. This is a receiving mechanism as data receiving means to be stored in the memory 7.

In the SAR signal processing system according to the present embodiment, the data after FFT is transmitted to the adjacent azimuth compression processor 2 by the transmission mechanism 8 in parallel with the azimuth compression processing in the azimuth compression processor 2, and The receiving mechanism 9 is configured to receive data after FFT transmitted from another adjacent azimuth compression processor 2.

Next, an operation of the SAR signal processing system according to the second embodiment of the present invention will be described mainly with reference to FIG. The basic operation of the SAR signal processing device according to the present embodiment is the same as in the first embodiment. That is, the observation data is divided in the azimuth direction, the range compression is processed in parallel by N range compression processors, the data after the range compression is divided in the range direction, and the data is divided in parallel by the M azimuth compression processors 2. While processing the azimuth compression, in parallel with the azimuth compression processing of the azimuth compression processor 2, the data transfer processor 5 transfers the FFT-processed data processed by the azimuth compression processor 2 to the adjacent azimuth compression processor 2.

Each azimuth compression processor 2 calculates ((n /
When M) × m) pieces of data are input, data is taken out line by line in the azimuth direction, that is, m pieces of data are taken out and azimuth compression processing is started. That is, FFT, range coverage correction, complex multiplication, and IFFT are performed on the extracted m pieces of data.

Each azimuth compression processor 2 performs an FFT process on each of the extracted azimuth-direction lines, that is, m data, that is, FFs in the azimuth direction.
Start T.

When each azimuth compression processor 2 completes the FFT processing, it stores the result in a predetermined position of the buffer memory 6 and instructs the data transfer processor 5 to transfer the data. And the next one in the azimuth direction
Line data, that is, m pieces of data, are taken out, and FFT in the azimuth direction is started.

The data transfer processor 5 is first processed by the transmission mechanism 8 in the azimuth compression processor 2 in parallel with the FFT processing of one line in the next azimuth direction of the azimuth compression processor 2, and then processed by the buffer memory 6. FF for one line in the azimuth direction stored in
The data after T, that is, m data are taken out and transferred to the receiving mechanism 9 of the adjacent azimuth compression processor 2 via the azimuth compression processor data transfer path 4.

The receiving mechanism 9 of the transferred data transfer processor 5 receives the data transmitted from the transmitting mechanism 8 of the adjacent azimuth compression processor 2 and stores it in a predetermined position of the buffer memory 7.

Here, since the data required when each azimuth compression processor 2 processes the range coverage correction exists in the adjacent azimuth compression processor 2 as shown in FIG. The receiving mechanism 9 in the compression processor 2 receives data from the transmission mechanism 8 in the second azimuth compression processor 2, and the transmission mechanism 8 in the second azimuth compression processor 2 receives data from the first azimuth compression processor 2. The transmission mechanism 9 in the second azimuth compression processor 2 receives data from the transmission mechanism 8 in the third azimuth compression processor 2 and transmits the data to the transmission mechanism 8 in the second azimuth compression processor 2. 8 transmits data to the receiving mechanism 9 in the second azimuth compression processor 2, Shin mechanism 9 receives data from the fourth transmission mechanism 8 of the azimuth compression processor 2,. . . The transmission mechanism 8 in the M-th azimuth compression processor 2 is (M-1) -th azimuth compression processor 2
The data will be transmitted to the receiving mechanism 9 inside.

On the other hand, since the data transfer path 4 for the azimuth compression processor is prepared for data transfer between the adjacent azimuth compression processors 2, the data transfer by the plurality of transmission mechanisms 8 and the reception mechanism 9 is respectively performed. It can be done independently and simultaneously.

Furthermore, since the transmission mechanism 8 in each azimuth compression processor 2 accesses the buffer memory 6 and the reception mechanism 9 accesses the buffer memory 7, they can operate simultaneously.

In the present embodiment, the first embodiment
The description of the same processing as described above will not be repeated.

Embodiment 3 First, the configuration of the SAR signal processing system according to the third embodiment of the present invention will be described with reference to FIG. In FIG. 3, 1 is a range compression processor for performing range compression, 2 is an azimuth compression processor for performing azimuth compression, and 3 is data for transferring processing data between the plurality of range compression processors 1 and the plurality of azimuth compression processors 2. A transfer path 4 is an azimuth compression processor data transfer path for transferring processing data between adjacent azimuth compression processors 2, and 5 is an intermediate processing result of the azimuth compression processor 2 in parallel with the processing of the azimuth compression processor 2. Is a data transfer processor for transferring data to and from an adjacent azimuth compression processor 2 via an azimuth compression processor data transfer path 4, a buffer memory 6 for storing the result of performing an FFT in the azimuth direction, and 7 a data transfer. Buffer memory for storing data transferred by processor 5 Reference numeral 8 denotes a transmission mechanism for transmitting the post-FFT data stored in the buffer memory 6 to the adjacent azimuth compression processor 2. Reference numeral 9 denotes the reception of the post-FFT data transmitted from the adjacent azimuth compression processor 2 to the buffer memory 7. Receiving mechanism to be stored in the
Reference numeral 0 denotes a bypass mechanism as transfer means for transferring data received from an adjacent azimuth compression processor 2 to another adjacent azimuth compression processor 2.

In the SAR signal processing system according to the third embodiment, the data after FFT is transmitted to the adjacent azimuth compression processor 2 by the transmission mechanism 8 in parallel with the azimuth compression processing in the azimuth compression processor 2 and The FFT data sent from another adjacent azimuth compression processor 2 is configured to be received by the receiving mechanism 9 or transferred to the adjacent azimuth compression processor 2 by the bypass mechanism 10 depending on the situation.

Next, an operation of the SAR signal processing system according to the third embodiment of the present invention will be described mainly with reference to FIG. The basic operation of the SAR signal processing device in the present embodiment is the same as in the first or second embodiment. That is, the observation data is divided in the azimuth direction, the range compression is processed in parallel by N range compression processors, the data after the range compression is divided in the range direction, and the data is divided in parallel by the M azimuth compression processors 2. While processing the azimuth compression, in parallel with the azimuth compression processing of the azimuth compression processor 2, the data transfer processor 5 transfers the FFT-processed data processed by the azimuth compression processor 2 to the adjacent azimuth compression processor 2.

Each azimuth compression processor 2 calculates ((n /
When M) × m) pieces of data are input, data is taken out line by line in the azimuth direction, that is, m pieces of data are taken out, and FFT in the azimuth direction is started.

When each azimuth compression processor 2 completes the FFT processing, it stores the result in a predetermined position of the buffer memory 6 and instructs the data transfer processor 5 to transfer the data. And the next one in the azimuth direction
Line data, that is, m pieces of data, are taken out, and FFT in the azimuth direction is started.

As shown in FIG. 12, when data necessary for processing the range coverage correction exists only in the adjacent azimuth compression processor 2, as shown in FIG. By the mechanism 8, the next azimuth direction of the azimuth
In parallel with the FFT processing for the line, the data is first processed in the azimuth compression processor 2 and
The data after one line in the azimuth direction, ie, m data, stored in the azimuth compression processor 2 is extracted and transferred to the receiving mechanism 9 in the adjacent azimuth compression processor 2 through the azimuth compression processor data transfer path 4. At the same time, the data is received by the receiving mechanism 9 from the transmitting mechanism 8 in the adjacent azimuth compression processor 2 and stored in a predetermined position of the buffer memory 7.

That is, the receiving mechanism 9 in the first azimuth compression processor 2 receives data from the transmission mechanism 8 in the second azimuth compression processor 2, and the transmission mechanism 8 in the second azimuth compression processor 2 The data is transmitted to the receiving mechanism 9 in the azimuth compression processor 2 and
The receiving mechanism 9 in the azimuth compression processor 2 is 3
The transmission mechanism 8 in the third azimuth compression processor 2 receives data from the transmission mechanism 8 in the second azimuth compression processor 2, and transmits the data to the reception mechanism 9 in the second azimuth compression processor 2, Receive data from the transmission mechanism 8 in the fourth azimuth compression processor 2, . . The transmission mechanism 8 in the M-th azimuth compression processor 2 has (M-
1) Data is transmitted to the receiving mechanism 9 in the azimuth compression processor 2.

Next, with reference to FIG. 6, description will be given of a case where data necessary for processing the range curvature correction exists in the three azimuth compression processors 2. FIG.

First, the data transfer processor 5 is first processed by the transmission mechanism 8 in the azimuth compression processor 2 in parallel with the FFT processing for one line in the next azimuth direction of the azimuth compression processor 2, and 6, the data after the FFT for one line in the azimuth direction stored in 6, that is, m pieces of data are taken out.
The bypass mechanism 10 in the adjacent azimuth compression processor 2 via the azimuth compression processor data transfer path 4
Transfer to

When it is necessary to store the transmitted data in its own azimuth compression processor 2, the bypass mechanism 10 stores the data at a predetermined position in the buffer memory 7 by the receiving mechanism 9.

When it is necessary to transfer the transmitted data to the next adjacent azimuth compression processor 2, the data is transferred to the bypass mechanism 10 in the adjacent azimuth compression processor 2 by the transmission mechanism 8. . However, if there is no need to transfer, it is not transferred.

That is, the bypass mechanism 10 in the first azimuth compression processor 2 receives data from the transmission mechanism 8 in the second azimuth compression processor 2, and the bypass mechanism 10 in the second azimuth compression processor 2 The bypass mechanism 10 in the third azimuth compression processor 2 receives data from the transmission mechanism 8 in the fourth azimuth compression processor 2, and the. . . The bypass mechanism 10 in the (M−1) th azimuth compression processor 2 receives data from the transmission mechanism 8 in the Mth azimuth compression processor 2. Then, the bypass mechanism 10 in the second azimuth compression processor 2 transfers the data to the first azimuth compression processor 2, and the bypass mechanism 10 in the third azimuth compression processor 2 transmits the data to the second azimuth compression processor 2. And transfer. . . (M-1)
Bypass mechanism 10 in the azimuth compression processor 2
Operates to transfer data to the (M-2) th azimuth compression processor 2.

In the third embodiment, the data required when performing range cover correction is 3
Although the case where there are three azimuth compression processors 2 has been described, the same applies to the case where there are three or more azimuth compression processors 2.

Embodiment 4 First, the configuration of the SAR signal processing system according to the fourth embodiment of the present invention will be described with reference to FIG. In FIG. 4, 1 is a range compression processor for performing range compression, 2 is an azimuth compression processor for performing azimuth compression, and 3 is data for transferring processing data between the plurality of range compression processors 1 and the plurality of azimuth compression processors 2. A transfer path 4 is an azimuth compression processor data transfer path for transferring processing data between adjacent azimuth compression processors 2, and 5 is an intermediate processing result of the azimuth compression processor 2 in parallel with the processing of the azimuth compression processor 2. Is a data transfer processor that transfers data to an adjacent azimuth compression processor 2 via an azimuth compression processor data transfer path 4, 6 is a buffer memory that stores the result of performing FFT in the azimuth direction, and 7 is a data transfer processor 5. Buffer memory for storing the transferred data, 11 Is information buffer memory as information storing means for storing information for identifying the data to be transferred adjacent to azimuth compression processor 2.

In the SAR signal processing system according to the present embodiment, based on the information stored in the information buffer memory 11, only the specific data of the data after the azimuth FFT stored in the buffer memory 6 is stored. Is transferred to the adjacent azimuth compression processor 2 by the data transfer processor 5.

Next, an operation of the SAR signal processing system according to the fourth embodiment of the present invention will be described mainly with reference to FIG. The basic operation of the SAR signal processing device according to the present embodiment is the same as in the first embodiment. That is, the observation data is divided in the azimuth direction, the range compression is processed in parallel by N range compression processors, the data after the range compression is divided in the range direction, and the data is divided in parallel by the M azimuth compression processors 2. While processing the azimuth compression, in parallel with the azimuth compression processing of the azimuth compression processor 2, the data transfer processor 5 transfers the FFT-processed data processed by the azimuth compression processor 2 to the adjacent azimuth compression processor 2.

Here, as shown in FIG. 12, the data required when the adjacent azimuth compression processor 2 performs the range coverage correction is one line in the azimuth direction, that is, a part of the data, not m data. It is. For example, in an SAR mounted on an artificial satellite or the like, data necessary for processing the range coverage correction by the adjacent azimuth compression processor 2 can be specified in advance. The information for specifying the data required when the information is stored can be stored in the information buffer memory 11 in advance.

Each azimuth compression processor 2 calculates ((n /
When M) × m) pieces of data are input, data is taken out line by line in the azimuth direction, that is, m pieces of data are taken out, and FFT in the azimuth direction is started.

When each azimuth compression processor 2 finishes the FFT processing, it stores the result in a predetermined position of the buffer memory 6 and instructs the data transfer processor 5 to transfer the data. And the next one in the azimuth direction
Line data, that is, m pieces of data, are taken out, and FFT in the azimuth direction is started.

The data transfer processor 5 performs an FFT for one line in the next azimuth direction of the azimuth compression processor 2.
In parallel with the above processing, the data after the FFT for one line in the azimuth direction stored in the buffer memory 6 should be transferred to the adjacent azimuth compression processor 2 specified by referring to the information buffer memory 11. The data is taken out and stored in a predetermined location of the buffer memory 7 in the adjacent azimuth compression processor 2 via the azimuth compression processor data transfer path 4.

That is, the data transfer processor 5 in the second azimuth compression processor 2 stores the data after FFT in the buffer memory 7 in the first azimuth compression processor 2 and the data in the third azimuth compression processor 2 The transfer processor 5 stores the data after the FFT in the buffer memory 7 in the second azimuth compression processor 2. . . The data transfer processor 5 in the M-th azimuth compression processor 2 stores the data after FFT in the buffer memory 7 in the (M-1) -th azimuth compression processor 2.

Embodiment 5 Next, the SAR according to the fifth embodiment of the present invention will be described with reference to FIG.
The configuration of the signal processing system will be described.

In the SAR signal processing system according to the fifth embodiment, the FFT in the azimuth direction to be transferred from the buffer memory 6 to the adjacent azimuth compression processor 2
The address of the buffer memory 6 for storing the subsequent data is
The information is stored in the information buffer memory 11 so that it can be directly referred to by the data transfer processor 5.

Next, an operation of the SAR signal processing system according to the fifth embodiment of the present invention will be described mainly with reference to FIG. The basic operation of the SAR signal processing device according to the present embodiment is the same as in the fourth embodiment. That is, the observation data is divided in the azimuth direction, the range compression is processed in parallel by N range compression processors, the data after the range compression is divided in the range direction, and the data is divided in parallel by the M azimuth compression processors 2. In addition to the azimuth compression processing, in parallel with the azimuth compression processing of the azimuth compression processor 2, only the data to be transferred out of the data after FFT processed by the azimuth compression processor 2 by the data transfer processor 5 is converted to the adjacent azimuth compression data. Transfer to processor 2.

For example, in an SAR mounted on an artificial satellite or the like, an FF in the azimuth direction required when the adjacent azimuth compression processor 2 processes the range coverage correction.
Since the data after T can be specified in advance, it is possible to directly refer to the address of the buffer memory 6 that stores the data after FFT in the azimuth direction to be transferred from the buffer memory 6 to the adjacent azimuth compression processor 2. As described above, the information is stored in the information buffer memory 11 in advance.

Each azimuth compression processor 2 calculates ((n /
When M) × m) pieces of data are input, data is taken out line by line in the azimuth direction, that is, m pieces of data are taken out, and FFT in the azimuth direction is started.

When each azimuth compression processor 2 completes the FFT processing, it stores the result in a predetermined position of the buffer memory 6 and instructs the data transfer processor 5 to transfer the data. And the next one in the azimuth direction
Line data, that is, m pieces of data, are taken out, and FFT in the azimuth direction is started.

The data transfer processor 5 performs an FFT for one line in the next azimuth direction of the azimuth compression processor 2.
In parallel with the processing of the above, based on the address stored in the information buffer memory 11, the FF
The data after T is taken out and stored in a predetermined location of the buffer memory 7 in the adjacent azimuth compression processor 2 via the azimuth compression processor data transfer path 4.

That is, the data transfer processor 5 in the second azimuth compression processor 2 stores the data after the FFT in the buffer memory 7 in the first azimuth compression processor 2 and the data in the third azimuth compression processor 2 The transfer processor 5 stores the data after the FFT in the buffer memory 7 in the second azimuth compression processor 2. . . The data transfer processor 5 in the M-th azimuth compression processor 2 stores the data after FFT in the buffer memory 7 in the (M-1) -th azimuth compression processor 2.

Embodiment 6 FIG. Next, the SAR according to the sixth embodiment of the present invention will be described with reference to FIG.
The configuration of the signal processing system will be described.

In the SAR signal processing system according to the sixth embodiment, the base address and the offset of the base address for the azimuth direction FFT data to be transferred to the adjacent azimuth compression processor 2 stored in the buffer memory 6 are stored in the information buffer. It is configured to be stored in the memory 11.

Next, an operation of the SAR signal processing system according to the sixth embodiment of the present invention will be described mainly with reference to FIG. The basic operation of the SAR signal processing device according to the present embodiment is the same as in the fourth embodiment. That is, the observation data is divided in the azimuth direction, the range compression is processed in parallel by N range compression processors, the data after the range compression is divided in the range direction, and the data is divided in parallel by the M azimuth compression processors 2. In addition to the azimuth compression processing, in parallel with the azimuth compression processing of the azimuth compression processor 2, only the data to be transferred out of the data after FFT processed by the azimuth compression processor 2 by the data transfer processor 5 is converted to the adjacent azimuth compression data. Transfer to processor 2.

For example, in an SAR mounted on an artificial satellite or the like, the azimuth direction FF required when the adjacent azimuth compression processor 2 processes the range coverage correction is used.
Since the data after T can be specified in advance, the base address and the offset of the base address for the data after FFT in the azimuth direction to be transferred to the adjacent azimuth compression processor 2 and stored in the buffer memory 6 are stored in advance. Is stored in the buffer memory 11.

Each azimuth compression processor 2 calculates ((n /
When M) × m) pieces of data are input, data is taken out line by line in the azimuth direction, that is, m pieces of data are taken out, and FFT in the azimuth direction is started.

When each azimuth compression processor 2 completes the FFT processing, it stores the result in a predetermined position of the buffer memory 6 and instructs the data transfer processor 5 to transfer the data. And the next one in the azimuth direction
Line data, that is, m pieces of data, are taken out, and FFT in the azimuth direction is started.

The data transfer processor 5 performs an FFT for one line in the next azimuth direction of the azimuth compression processor 2.
In parallel with the above processing, the base address and the offset stored in the information buffer memory 11 are obtained, and the data after FFT stored in the address of the buffer memory 6 to which the base address and the offset are added is taken out. The data is stored in a predetermined location of the buffer memory 7 in the adjacent azimuth compression processor 2 via the azimuth compression processor data transfer path 4.

That is, the data transfer processor 5 in the second azimuth compression processor 2 stores the data after the FFT in the buffer memory 7 in the first azimuth compression processor 2 and the data in the third azimuth compression processor 2 The transfer processor 5 stores the data after the FFT in the buffer memory 7 in the second azimuth compression processor 2. . . The data transfer processor 5 in the M-th azimuth compression processor 2 stores the data after FFT in the buffer memory 7 in the (M-1) -th azimuth compression processor 2.

Embodiment 7 FIG. First, the configuration of the SAR signal processing system according to the seventh embodiment of the present invention will be described with reference to FIG. In FIG. 5, 1 is a range compression processor for performing range compression, 2 is an azimuth compression processor for performing azimuth compression, and 3 is data for transferring processing data between the plurality of range compression processors 1 and the plurality of azimuth compression processors 2. A transfer path 4 is an azimuth compression processor data transfer path for transferring processing data between adjacent azimuth compression processors 2, and 5 is an azimuth compression processor 2 in parallel with the processing of the azimuth compression processor 2.
A data transfer processor for transferring the intermediate processing result to an adjacent azimuth compression processor 2 via an azimuth compression processor data transfer path 4, a buffer memory 6 for storing the result of performing an FFT in the azimuth direction,
Reference numeral 7 denotes a buffer memory for storing data transferred by the data transfer processor 5, reference numeral 11 denotes an information buffer memory for storing information for specifying data to be transferred to the adjacent azimuth compression processor 2, and reference numeral 12 denotes an adjacent azimuth compression processor. 2 is a control processor as control means for calculating information for specifying data to be transferred to the information buffer 2 and storing the result in the information buffer memory 11.

In the SAR signal processing system according to the seventh embodiment, the control processor 12
Information for specifying data to be transferred to the adjacent azimuth compression processor 2 is calculated, and the result is stored in the information buffer memory 11. The FF in the azimuth direction stored in the buffer memory 6 based on the information calculated here.
Of the data after T, only specific data is transferred by the data transfer processor 5 to the adjacent azimuth compression processor 2.

Next, the operation of the SAR signal processing system according to the seventh embodiment of the present invention will be described mainly with reference to FIG. The basic operation of the SAR signal processing device according to the present embodiment is the same as in the first embodiment. That is, the observation data is divided in the azimuth direction, the range compression is processed in parallel by N range compression processors, the data after the range compression is divided in the range direction, and the data is divided in parallel by the M azimuth compression processors 2. In addition to processing the azimuth compression, in parallel with the azimuth compression processing of the azimuth compression processor 2, only the data to be transferred, of the data after the FFT processed by the azimuth compression processor 2 by the data transfer processor 5, is subjected to the adjacent azimuth compression. Transfer to processor 2.

However, for example, S
In the AR, data after the FFT in the azimuth direction, which is necessary when the adjacent azimuth compression processor 2 performs the range cover correction, cannot be specified in advance. Therefore, it is necessary to calculate or change which azimuth direction data after the FFT is required in the adjacent azimuth compression processor 2 according to the situation.

In the N range compression processors, when the observation data is divided in the azimuth direction and the range compression processing is started in parallel, the control processor performs range coverage correction in each azimuth compression processor 2 based on the altitude, speed, and the like. Is calculated after the FFT in the azimuth direction, which is required in the case of processing.

When the range compression processing in the N range compression processors is completed, the M azimuth compression processors 2
When the transfer of the data after range compression to the azimuth compression processor 2 is started, the control processor transfers the data to the information buffer memory 11 in each azimuth compression processor 2 and the adjacent azimuth compression processor 2 based on the previously calculated result. Information for specifying data after FFT in the power azimuth direction is stored.

Each azimuth compression processor 2 calculates ((n /
When M) × m) pieces of data are input, data is taken out line by line in the azimuth direction, that is, m pieces of data are taken out, and FFT in the azimuth direction is started. When each azimuth compression processor 2 completes the FFT processing,
The result is stored in a predetermined position of the buffer memory 6, and the data transfer processor 5 is instructed to transfer the data. Then, the next one line in the azimuth direction, that is, m data is extracted, and the FFT in the azimuth direction is started.

The data transfer processor 5 performs an FFT for one line in the next azimuth direction of the azimuth compression processor 2.
In parallel with the above processing, the data after the FFT for one line in the azimuth direction stored in the buffer memory 6 should be transferred to the adjacent azimuth compression processor 2 specified by referring to the information buffer memory 11. The data is taken out and stored in a predetermined location of the buffer memory 7 in the adjacent azimuth compression processor 2 via the azimuth compression processor data transfer path 4.

That is, the data transfer processor 5 in the second azimuth compression processor 2 stores the data after FFT in the buffer memory 7 in the first azimuth compression processor 2 and the data in the third azimuth compression processor 2 The transfer processor 5 stores the data after the FFT in the buffer memory 7 in the second azimuth compression processor 2. . . The data transfer processor 5 in the M-th azimuth compression processor 2 stores the data after FFT in the buffer memory 7 in the (M-1) -th azimuth compression processor 2.

[0108]

The SAR signal processing system according to the present invention is configured as described above. In particular, data necessary for range coverage correction from an adjacent azimuth compression processor is as follows.
By transferring data from an adjacent azimuth compression processor in parallel and independently of the azimuth compression processing in the azimuth compression processor, a memory bottleneck and a bus bottleneck can be eliminated.

In the SAR signal processing system according to the present invention, the transmission of data to the adjacent azimuth compression processor and the reception of data from another adjacent azimuth compression processor are performed at the same time. Data transfer between azimuth compression processors can be performed at high speed.

The SAR signal processing system according to the present invention is further provided with a transfer means for transferring data transmitted from an adjacent azimuth compression processor to another adjacent azimuth compression processor. Range coverage correction can be processed even when the proper data exists in non-adjacent azimuth compression processors.

The SAR signal processing system according to the present invention further includes information storage means for storing information for specifying data to be transferred by the data transfer processing means, and transfers only data required by an adjacent azimuth compression processor. By doing so, the amount of data transferred between adjacent azimuth compression processors can be reduced.

In the SAR signal processing system according to the present invention, the data required by the adjacent azimuth compression processor is specified by the base address and the offset, so that the offset for each azimuth line is fixed in the range coverage correction. Therefore, it is possible to reduce the amount of memory required for specifying data required by the adjacent azimuth compression processor.

The SAR signal processing system according to the present invention is further provided with control means for changing data required by an adjacent azimuth compression processor depending on the situation. In addition, even when the data required by the adjacent azimuth compression processor is not constant, the processing can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a synthetic aperture radar signal processing system according to a first embodiment of the present invention;

FIG. 2 is a block diagram showing a configuration of a synthetic aperture radar signal processing system according to a second embodiment of the present invention;

FIG. 3 is a block diagram showing a configuration of a synthetic aperture radar signal processing system according to a third embodiment of the present invention;

FIG. 4 is a block diagram showing a configuration of a synthetic aperture radar signal processing system according to a fourth embodiment of the present invention;

FIG. 5 is a block diagram showing a configuration of a synthetic aperture radar signal processing system according to a seventh embodiment of the present invention;

FIG. 6 divides azimuth compression into M pieces in the range direction,
FIG. 9 is a diagram showing a state in which data necessary for range coverage correction exists in three azimuth compression processors when processing is performed in parallel by three azimuth compression processors;

FIG. 7 is a diagram showing a flow of an SAR image reproduction process;

FIG. 8 is a view showing a range curvature correction;

FIG. 9 is a diagram showing a data structure of SAR observation data;

FIG. 10 is a diagram showing a state in which observation data is divided and input to N range compression processors in the azimuth direction,

FIG. 11 is a diagram showing a state in which data after range compression is divided and input in the range direction to M azimuth compression processors;

FIG. 12 is a diagram showing a problem of range coverage correction that occurs when azimuth compression is divided into M in the range direction and processed in parallel by M azimuth compression processors;

FIG. 13 is a block diagram showing a configuration of a conventional synthetic aperture radar signal processing system;

FIG. 14 is a block diagram showing a configuration of a conventional synthetic aperture radar signal processing system;

FIG. 15 is a block diagram showing a configuration of a conventional synthetic aperture radar signal processing system.

[Explanation of symbols]

1 range compression processor, 2 azimuth compression processor, 3 data transfer path, 4 data transfer path for azimuth compression processor, 5 data transfer processor, 6
Buffer memory, 7 buffer memory, 8 transmission mechanism, 9 reception mechanism, 10 bypass mechanism, 12 control processor, 11 buffer memory for information, 13
Azimuth compression processor, 14 shared memory, 15
Specific memory for range coverage correction, 16 shared bus.

Claims (7)

[Claims] 1. Range compression processing means for dividing imaging data by a synthetic aperture radar in the azimuth direction and performing compression processing in the range direction in parallel, and data compressed in the range direction by the range compression processing means in the range direction. Azimuth compression processing means for performing compression processing in the azimuth direction in parallel with the azimuth compression processing means connected to the azimuth compression processing means; A synthetic aperture radar signal processing system comprising: data transfer processing means for transferring. 2. The data transfer processing means according to claim 1, wherein said data transfer processing means transmits an intermediate processing result of said own azimuth compression processing means to an adjacent azimuth compression processing means; 2. The synthetic aperture radar signal processing system according to claim 1, further comprising data receiving means for receiving an intermediate processing result of the azimuth compression processing means. 3. The data transfer processing means according to claim 1, wherein the intermediate processing result transmitted from the adjacent azimuth compression processing means is
3. The synthetic aperture radar signal processing system according to claim 1, further comprising a transfer unit for transferring the data to another adjacent azimuth compression processing unit. 4. The data transfer processing means includes an information storage means for storing information for specifying data to be transferred, and refers to the information storage means to convert desired data to be transferred to an adjacent azimuth compression circuit. 4. The synthetic aperture radar signal processing system according to claim 1, wherein the signal is transmitted to a processing unit. 5. The information storage means stores an address of data to be transferred stored in a means for storing a processing result of the azimuth compression processing means, and the data transfer processing means transfers the data by referring to the address. 5. The synthetic aperture radar signal processing system according to claim 4, wherein data to be read is read and transmitted to an adjacent azimuth compression processing means. 6. The information storage means stores a base address and an offset of data to be transferred stored in a means for storing a processing result by the azimuth compression processing means, and the data transfer processing means stores 5. The synthetic aperture radar signal processing according to claim 4, wherein data to be transferred is read from an address calculated from the base address and the offset stored in the storage means and transmitted to an adjacent azimuth compression processing means. system. 7. A control means connected to the information storage means for calculating information specifying data to be transferred to an adjacent azimuth compression processing means according to a situation, and storing the calculation result in the information storage means. 7. The synthetic aperture radar signal processing system according to claim 4, wherein data to be transferred is specified and read out from the calculation result and transmitted to an adjacent azimuth compression processing unit.