JPS58191979A - Picture processing system of synthetic aperture radar - Google Patents

Abstract

PURPOSE:To form a system where a high-speed processing is possible, by providing a data buffer for range curvature compensation processing in an azimuth direction compressing means. CONSTITUTION:Input data of an azimuth compression processing device 4 is transposed range compression data of a two-dimensional picture memory 3 and is read out line by line and is distributed to each parallel processing device, and picture data is converted to one-line data in a frequency space by an FET device 4A and is stored in a shared memory 9 in the order of line number. A range curvature compensation resampling device 4B on each parallel processing device resamples data in the shared memory 9 in accordance with a curve of the secondary degree given from a CPU; but since the position is not specified concerning line number, it is necessary to access all outputs of the FET device 4A of each parallel processing device. The product between the output of the range curvature compensation resampling device 4B and a reference function is operated in a complex multiplying device 4C, and this output is converted to a real picture by an IFFT device 4D.

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention The present invention relates to a synthetic aperture radar mounted on an artificial satellite or an aircraft.
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The present invention relates to a digital processing system for reproducing images that can be understood by humans from imaging data obtained by ``8ARj'' (hereinafter referred to as "8ARj"), and particularly to a processing system suitable for high-speed processing of SAR data.

Conventionally, in the field of remote sensing using artificial satellites or aircraft, 8AR is attracting attention as a sensor for imaging the earth's surface, as it can obtain high-resolution wit images in the microwave band that transmits through spirits.

Figure 1 shows the entire system of 81R. A BAR equipped with a radar sensor fR and an antenna A11 is mounted on an artificial satellite or the like and images the ground surface while moving along a flight path in the direction of arrow A. Imaging data from the SAR is received by the ground station L1 and processed by a data processor to create an image film IP, a magnetic tape MT for data storage, etc.

Furthermore, C#'! In the decomposition cell, R indicates the range direction on the ground surface of the data collected by 8AR, Az indicates the threshold azimuth direction, AB indicates the antenna beam, and o and ri indicate the cutting width, respectively.

Below, we will outline the processing of data collected by 8AR. For details, see, for example, J.

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ynthetic ApertureRadar )w
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In the received image of 81H, one point on the original image is distributed with the spread of a point spread pattern h (x, y),
Humans cannot understand this.

Here, X indicates the range direction, and y indicates the azimuth direction. The information spread in the received image is
First, it is compressed in the range direction, and then in the azimuth direction. The compression processing is performed by correlay processing with point image pattern data for each line of image data.
However, if the correlative eye processing is executed as it is, it will take a huge amount of processing time, so the fast 7-lier transform (hereinafter referred to as 1'
- FFT), complex multiplication, fast inverse 7-lier transform (
Speed-up is achieved using IFFTJ (hereinafter referred to as IFFTJ).

The above is the basics of SAR data processing, but in order to improve image quality, other processing such as range car correction is essential. This is to remove the blur pattern that appears in the processed W image by changing the range car beam), and to remove the blur pattern that appears in the processed W image. orbit,
Data on a quadratic curve determined by the posture is obtained and used as new array data. Therefore, the range curvature correction process ll! This is not possible with IFi line-by-line processing.
In order to create one line of correction data, frequency space data including all of the quadratic curves is required. However, in conventional SAR double image processing systems, in order to perform a series of image processing at a sufficiently high speed, many dedicated processors are used in parallel according to the processing algorithm.
Moreover, the system 4I is arranged in a pipeline and has a memory dedicated to transposing two-dimensional data in between! He was possessing authority.

FIG. 2 shows an example. In Fig. 2, 1 is a magnetic tape on which the received 8mmR data is recorded, 2 is a system for compressing the data line by line in the range direction, and 3 is for vertically and horizontally transposing the compressed 2-dimensional data in the range direction. A two-dimensional image memory for, number 5 is a system that compresses transposed data line by line in the azimuth direction.
Fi compression [magnetic tape that stores 1 data, and 6F
i is a CPU that controls these. Here, the azimuth direction compression processing system 4 has a configuration in which vIWl processors are arranged in parallel for line-by-line processing, and when performing the above-mentioned range curvature correction processing,
The main storage device 7 of the OPU 6 for controlling the entire system will be used as a data buffer for range car control, and due to a bus neck, processing d! There was a problem that the degree of decrease was ta<.

Purpose of the Invention The present invention has been made in view of the above circumstances, and its purpose is to solve the above-mentioned problems in the conventional 8AR image processing system and to develop an 8AR image processing system capable of high-speed processing.
The purpose of this invention is to provide an image processing system.

The gist of the present invention is to provide an 8AR image processing system having means for compressing received 8AR data in the range direction, means for vertically and horizontally transposing the range direction compressed two-dimensional data, and means for compressing the transposed data in the azimuth direction. This is achieved by providing a data buffer for range curpture correction processing in the SM R processing 11 algorithm in the azimuth direction compression means.

Embodiment of the Invention FIG. 3 shows an embodiment of the present invention, in which the i! of 81R shown in FIG. A shared memory between parallel processing devices as a data buffer for range curvature correction MW is provided in the azimuth direction compression means Φ in the Ii image processing system. In Figure 3, 4 is the azimuth pressure supply short term 1 position, and 4 is FFT! 'j#, 4B is a sample filter for range carpture capture, 4C is a complex multiplier, 4D is an I
The operation of the device of this embodiment constructed as described above, including the IFFT power supply, the aVi distribution device, and 9, all of which are memories, will be described below.

The input data to the azimuth compression processing device 4 is the transferred range compressed data in the two-dimensional image memory 3, which is successively outputted one line at a time, and is divided one line at a time to each parallel processing device by the distributor f18. The image data of this one line is FFT
The data is converted into one line data in frequency space by the device 11M4A, and stored in the shared memory 9 in line number order. Resample M for range curvature correction on each parallel processing device! 4BFi, C! The data in the shared memory 9l: is resampled (interpolated) according to the quadratic curve given from the PU6. Since this data sample position It is not specified with respect to the line number, it is necessary to access all outputs of the IFFT device ff 4 A on each parallel processing device. Sample setup for range curvature correction f!
The output of t4B is multiplied with a reference function by the calculation unit 40 in the same way as in the past, and then converted into a real PAe by the IPFT unit 4D.

FIG. 4 shows another embodiment of the present invention, in which the same function as the shared memory 9 shown in the above embodiment is realized by a unique memory 10 and a common data bus 11 provided in each parallel processing device. In the device of this embodiment, FFT-completed data from other parallel processing devices is sent through the common data bus 11. Note that when each parallel processing device uses only part of the data in the frequency space of image data, it is more advantageous to provide each parallel processing device with its own memory than to provide a shared memory (see Section 6). Figure #see)
0 FIG. 6 shows still another embodiment of the present invention, and in the figure, a 12Fi distributor, 13 a shift register, 1
4-#-i coefficient unit, 15! -j adder and 16 is a decimated look adder. In the device of this embodiment, 2
The range-direction compressed data sequentially output from the dimensional memory 3 is input to a shift register 13 having a number of stages equal to the number of parallel processes, and the contents of each shift register are multiplied by a predetermined coefficient. ? 'n15 takes the sum 9, and the distributor 12 distributes it to each parallel processing device one data at a time. Therefore, each parallel processing device processes the same azimuth direction line data one after another, and data at corresponding positions of different lines is accumulated in the specific memory 10 of each parallel processing device. , this means that thinning data corresponding to different positions on the same line is input, and the output w
Since the partial look addition is performed in which the 4-day data is added, there is an effect that the S/N ratio can be improved. Furthermore, since the device of this embodiment does not exchange data between the respective parallel processing devices, it also has the effect of simplifying the configuration and calculation control. However, since one line data is thinned out and processed, the azimuth direction signal band exceeds the sampling frequency, so it is necessary to perform band reduction processing as shown in FIG. 7 before distributing each data item.

Effects of the Invention As described above, the present invention provides 8Al' for Itfs reception.
8AR17) An image processing system comprising means for compressing L data in the range direction, means for vertically and horizontally transposing the two-dimensional data already compressed in the range direction, and means for compressing the transposed data in the azimuth direction. in the direction compression means,
Since a data buffer is provided for range curvature correction processing in the 8A'R processing algorithm, it is possible to speed up processing and simplify arithmetic control.

[Brief explanation of drawings]

Figure 1 shows the overall FiSAR system, Figure 2 shows the configuration of the conventional 8AR W image processing system, and Figure 31 shows the configuration of the conventional 8AR W image processing system.
5!5 to 6 are diagrams showing examples of actual mackerel according to the present invention, and FIG. 7 is a diagram showing a band reduction process. 2: Range compression processing unit fit, 12-dimensional memory, 4: Azimuth compression processing unit, 6: OPU, 8: Distribution device,
9: Shared memo 'J, 10F unique memory, 11: Common data bus, 12: Distribution hole:, 13 Niji 7 register, 14
; Coefficient unit, 15: Adder, 16; Decimation look adder 14. Patent Applicant Hitachi, Ltd. Representative Patent Attorney Masatoshi Isomura - No. 1 Figure 8 Figure 3 Figure 4 413 Ushi C41) ', , Ushi No. 5 Figure 6 Figure 7 Figure 7 Continued from page 1 0 Inventor: Fuminobu Furumura, Hitachi, Ltd. System Development Laboratory, 1099 Ozenji, Tama-ku, Kawasaki City; Inventor: Yutaka Kubo; 5-2-1 Hitachi University, Mika-cho; Inumika Factory, Hitachi, Ltd.

Claims (1)

[Claims] means for parallel processing imaging data by synthetic aperture radar and compression processing in the range direction; means for vertically and horizontally transposing the data compressed in the range direction by the means; and parallel processing of the data transposed by the means; An image processing system for a synthetic aperture radar comprising means for performing compression processing in the azimuth direction, wherein a partial image data buffer is provided in the means for performing compression processing in the azimuth direction. system.