JP2001289945A - Synthetic aperture radar device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a synthetic aperture radar device capable of detecting target scattering points with resolution higher than that decided by a variation Δf in the carrier frequency of pulse at a high speed. SOLUTION: This synthetic aperture radar device is constituted of a scattering point number estimating means 4 for estimating the number of target scattering points included in received observation data, a position estimating means 6 for estimating positions of the individual target scattering points estimated by the scattering point number estimating means, and a reflection intensity estimating means 8 for estimating reflection intensity of the individual target scattering points estimated by the scattering point number estimating meas. The scattering point number estimating means 4, the position estimating means 6 and the reflection intensity estimating means 8 are respectively composed of plural basic processing means 5, 7 and 9 for simultaneously and parallelly performing processing plural data trains.

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 (Synthetic AP) mounted on a satellite or an aircraft.
The present invention relates to a digital processing system (hereinafter, referred to as a synthetic aperture radar device) for reproducing an image that can be understood by humans from image data obtained by erture radar (hereinafter, referred to as SAR).

[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. The imaging data (hereinafter, referred to as observation data) received by the SAR has a two-dimensional spread in the range direction and the azimuth direction, and cannot be understood by humans as it is, so that an image (hereinafter, referred to as human) can be understood.
(Hereinafter referred to as "reproduced image").

[0003] Conventionally, as a synthetic aperture radar apparatus which performs image reproduction processing and generates a reproduced image from observation data, for example, there is one disclosed in Japanese Patent Application Laid-Open No. H2-243987. FIG. 12 is a block diagram showing an example of a conventional synthetic aperture radar device described in Japanese Patent Application Laid-Open No. 2-243987. In FIG. 12, reference numeral 1 denotes a range compression unit for compressing observation data in a range direction, and includes a plurality of range compression processors 17. Reference numeral 2 denotes an azimuth compression unit for compressing the range-compressed data compressed in the range direction by the range compression unit 1 in the azimuth direction, and includes a plurality of azimuth compression processors 18.

In a conventional synthetic aperture radar apparatus, observation data having a two-dimensional spread in the range direction and the azimuth direction is obtained by performing correlation processing (convolution operation) between the range reference function and the azimuth reference function (convolution operation). A configuration is adopted in which a reproduced image is generated by compressing in the direction. In order to generate a reproduced image at high speed, a plurality of range compression processors 17 perform a plurality of range direction compression processes (hereinafter, referred to as range compression), and a plurality of azimuth compression processors 18 perform a plurality of azimuth direction compression processes (hereinafter, referred to as range compression processes). Hereinafter, azimuth compression is performed in parallel.

Next, a conventional synthetic aperture radar device will be described. FIG. 13 is a diagram showing a flow of a conventional SAR image reproduction process. In the conventional SAR image reproduction processing, observation data is compressed in the range direction by correlation processing between the observation data and the range reference function, and then compressed in the azimuth direction by correlation processing with the azimuth reference function. At this time, in the digital processing, if the correlation processing is executed as it is, it takes a huge processing time. Therefore, the speed is increased by using fast Fourier transform (hereinafter, referred to as FFT), complex multiplication, and inverse fast Fourier transform (hereinafter, referred to as IFFT). Is generally achieved.

Further, in order to improve the quality of a reproduced image, processing such as range migration correction is indispensable. The range migration correction is for correcting blur caused by a change in the distance (range) between the SAR and the imaging target, and examples thereof include range coverage correction and range walk correction. In the range coverage correction, on the frequency space in the middle of compression in the azimuth direction, that is, after performing the FFT in the azimuth direction, FIG.
The same range data distributed on the quadratic curve shown in (a) is resampled (interpolated and picked up) on a straight line as shown in FIG. 14 (b).

As shown in FIG. 15, the observation data is composed of n data in the range direction and m data in the azimuth direction. As shown in FIG. 16, such observation data is divided into n pieces in the azimuth direction, and each is input to the n number of range compression processors 17. That is, each range compression processor 17 has n in the range direction.
And (m / N) data in the azimuth direction.

[0008] Each range compression processor 17 calculates (n ×
When (m / N)) pieces of data are input, data is extracted for each line in the range direction, that is, n pieces of data are extracted and range compression processing is performed. In other words, FFT, complex multiplication, IFFT
Is carried out. By repeating this (m / N) times,
Range compression is performed on all input data.

Next, each range compression processor 17 converts the data after range compression into m azimuth compression processors 1.
Transfer to 8. At this time, as shown in FIG. 17, the data is transferred so as to be divided into m in the range direction. That is, each azimuth compression processor 18 receives (n / M) data in the range direction and m data in the azimuth direction.

Each azimuth compression processor 18 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.

As a result, the observation data is compressed in the range direction and the azimuth direction, and a reproduced image having n × m pixels can be obtained. Each pixel value is the reflection intensity of the area, and a target scattering point can be detected by comparing this value.

[0012]

Since the conventional synthetic aperture radar apparatus is configured as described above, if two adjacent target scattering points are separated and detected, the resolution becomes the size of a pixel. Here, the size of the pixel cannot be smaller than the minimum interval defined by the pulse width corresponding to the reciprocal 1 / Δf of the variation Δf of the carrier frequency of the pulse, ie, (light speed / 2Δf). In other words, when a plurality of target scattering points exist in the same pixel, there is a problem that they cannot be separated and detected.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a synthetic aperture radar apparatus capable of detecting a target scattering point at a high speed with a resolution not less than a resolution Δf of a carrier frequency of a pulse. The purpose is to gain.

[0014]

A synthetic aperture radar apparatus according to the present invention includes a scatter point number estimating means for estimating the number of target scatter points included in received observation data, and an individual scatter point number estimated by the scatter point number estimating means. Position estimating means for estimating the position of the target scattering point, and reflection intensity estimating means for estimating the reflection intensity of each target scattering point estimated by the scattering point number estimating means, wherein the scattering point number estimating means, the position The estimating means and the reflection intensity estimating means are each constituted by a plurality of basic processing means for simultaneously processing a plurality of data strings in parallel.

Further, a range compression means for compressing the observation data in the range direction, an azimuth compression means for compressing the range-compressed data compressed in the range direction by the range compression means in the azimuth direction, and the azimuth compression means Frequency conversion means for converting the generated first reproduced image into a frequency domain, based on the data in the frequency domain converted by the frequency conversion means, the scattering point number estimation means, the position estimation means and the The second reproduction image is generated by the reflection intensity estimating means.

Further, the apparatus further comprises an image holding means for storing the first reproduced image generated by the range compressing means and the azimuth compressing means, based on the first reproduced image stored in the image holding means in advance. A second reproduced image is generated by the frequency converting means, the scattering point number estimating means, the position estimating means, and the reflection intensity estimating means.

An azimuth compression means for compressing the observation data in the azimuth direction; and a range compression means for compressing the azimuth-compressed data compressed in the azimuth direction by the azimuth compression means in the range direction and outputting the data in the frequency domain. Means, further based on the data after range compression in the frequency domain generated by the range compression means,
A reproduced image is generated by the scattering point number estimating means, the position estimating means, and the reflection intensity estimating means.

Further, there is further provided a time conversion means for converting the data after range compression in the frequency domain generated by the range compression means into a time domain to generate a reproduced image.

Further, a data sequence given to each of the basic processing means so that the processing loads of the basic processing means constituting the position estimating means and the reflection intensity estimating means are balanced in accordance with the number of target scattering points. It is characterized by further comprising a processing load balancing means for adjusting.

Further, the processing load balancing means provides the basic processing means constituting the position estimating means and the reflection intensity estimating means according to the number of target scattering points estimated by the scattering point number estimating means. It is characterized in that a data string is adjusted.

Further, the apparatus further comprises scattered point number predicting means for predicting the number of target scattered points from the first reproduced image generated by the range compressing means and the azimuth compressing means, wherein the processing load balancing means comprises: According to the present invention, a data sequence to be provided to each of the basic processing means constituting the position estimating means and the reflection intensity estimating means is adjusted according to the number of target scattering points obtained by the point estimating means.

Further, the scattering point number predicting means predicts that there is a target scattering point when the reflection intensity of the partial area obtained from the first reproduced image is higher than a certain level. .

The scattering point number predicting means predicts the number of target scattering points included in the partial area according to a certain level of the reflection intensity of the partial area obtained from the first reproduced image. Is what you do.

Further, the scattering point number predicting means predicts the number of existing target scattering points according to the distribution of the reflection intensity obtained from the first reproduced image.

The scattering point number estimating means estimates the number of target scattering points estimated by the scattering number estimating means, the position of the target scattering point estimated by the position estimating means, and the reflection intensity estimating means. It is characterized in that the reflection intensity at the target scattering point is obtained, and the prediction method is corrected so as to obtain a more accurate prediction value from these results.

Further, the processing load balancing means assigns a large number of the basic processing means of the position estimating means and the reflection intensity estimating means to a data string having a large number of target scattering points. is there.

Further, the processing load balancing means assigns a data string so that the number of target scattering points to be processed by each of the basic processing means of the position estimating means and the reflection intensity estimating means is the same. It is.

Further, according to the target number of scattering points obtained by the number of scattering points estimating means, a data sequence to be processed by the number of scattering points estimating means, the position estimating means and the reflection intensity estimating means or a processing order of a plurality of data strings. And a processing load control unit for controlling the processing load.

Further, the processing load control means controls the scattering point number estimating means, the position estimating means, and the reflection intensity so as not to process the data sequence predicted by the scattering point number estimating means to have no target scattering point. It is characterized by controlling the estimating means.

Further, the processing load control means determines the priority of the data sequence to be processed according to the number and distribution of the target scattering points predicted by the scattering point number predicting means,
The scatter point number estimating means, the position estimating means, and the reflection intensity estimating means are controlled so as to perform processing in descending order of priority.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a block diagram showing a configuration of a synthetic aperture radar apparatus according to Embodiment 1 of the present invention. In FIG. 1, reference numeral 1 denotes a range compression unit for compressing observation data in the range direction, and 2 denotes an azimuth compression unit for compressing the range-compressed data compressed in the range direction by the range compression unit 1 in the azimuth direction.
3 is a frequency conversion means for converting the first reproduced image generated by the range compression means 1 and the azimuth compression means 2 into a frequency domain, and 4 is a target scattering point based on the frequency domain data converted by the frequency conversion means 3. The number-of-scattering-points estimating means 6 for estimating the number of target scattering points, and the position estimating means 8 for estimating the position of each of the target scattering points estimated by the number-of-scattering-points estimating means 4, and the reflection intensity of each of the target scattering points are estimated. The reflection intensity estimating means is shown. The scattering point number estimating means 4, the position estimating means 6, and the reflection intensity estimating means 8 include a plurality of basic processing means 5, 7, and 9, respectively.

In the synthetic aperture radar apparatus according to the first embodiment, the first reproduced image generated by the range compressing means 1 and the azimuth compressing means 2 is converted into the frequency domain converted by the frequency converting means 3, and the number of scattering points The estimating means 4, the position estimating means 6 and the reflection intensity estimating means 8 estimate the number of target scattering points and the positions and reflection intensities of the individual target scattering points, as well as the scattering point number estimating means 4 and the position estimating means 6.
The reflection intensity estimating means 8 employs a method in which a plurality of basic processing means 5, 7, and 9 simultaneously process a plurality of data strings.

Next, the operation will be described. FIG. 2 is a diagram showing the flow of the SAR image reproduction process according to the first embodiment. First, similarly to the conventional SAR image reproduction process shown in FIG. 13, observation data having a two-dimensional spread in the range direction and the azimuth direction is correlated with the range reference function and the azimuth reference function (convolution). The first reproduction image is generated by performing compression in the range direction and the azimuth direction by the calculation). Next, the first reproduced image is converted to the frequency domain, and by analyzing this frequency component, the number of target scattering points, the position of each target scattering point, and the reflection intensity are estimated. Generate

Here, as a method of estimating the number of target scattering points, the position of each target scattering point, and the reflection intensity, the arrival direction of an incident signal, that is, the direction of the target scattering point, is determined from the received signal of the antenna with high resolution. Apply a high-resolution angle measurement algorithm that can be estimated by As a high-resolution angle measurement algorithm that estimates the target scattering point from the frequency component,
For example, MUSIC (Multiple Signal Classification)
Method, ESPRIT (Estimation of Signal Parameters via Ro
tational Invariance Technique), MEM (Maximum E)
ntropy Method), Capon method, etc., are known.
le Emitter Location and Signal Parameter Estimatio
n (by ROSchmidt, IEEE Trans. AP-34, 3, pp.276-28
0,1986) shows that a target scattering point can be detected with a resolution higher than the resolution specified by the pulse width.

That is, the first reproduced image is regarded as a received signal of the antenna, and a high-resolution angle measurement algorithm is applied thereto, thereby obtaining a pulse signal obtained by a conventional correlation process with a range reference function and an azimuth reference function. The target scattering point can be detected with a resolution higher than the resolution defined by the pulse width corresponding to the reciprocal 1 / Δf of the carrier frequency change Δf.

Further, by configuring the data sequence for one line in each range direction of the first reproduced image as a received signal of one antenna and applying a high-resolution angle measurement algorithm, one line in each range direction is obtained. The number of target scattering points by the high-resolution angle measurement algorithm for the minute data sequence,
Since the processing for estimating the position and reflection intensity of each target scattering point can be performed independently, the scattering point number estimating means 4, the position estimating means 6, and the reflection intensity estimating means 8 are constituted by a plurality of basic processing means. By doing so, the process of estimating the number of target scattering points, the position of each target scattering point, and the reflection intensity for a plurality of data lines for one line in the range direction can be performed simultaneously and in parallel. Enables higher speed.

Based on the above processing procedure, the first embodiment
Operates in the following manner. First, a first reproduced image is generated from the observation data received by the range compression unit 1 and the azimuth compression unit 2. This procedure is similar to that of the conventional synthetic aperture radar device. That is, along with the flow of the conventional SAR image reproduction process shown in FIG. 13, the observation data having a two-dimensional spread in the range direction and the azimuth direction is obtained by correlating the observation data with the range reference function and the azimuth reference function ( By performing compression in the range direction and the azimuth direction by a convolution operation, a first reproduced image is generated.

The observation data is first input to the range compression means 1. The range compression means 1 performs a compression process in the range direction by performing a correlation process between the observation data and the range reference function. In other words, data is taken out line by line in the range direction, FFT, complex multiplication, and IFFT are performed, and this is performed on all data, thereby completing range compression. Here, the range compressing means 1 may be configured so as to be able to simultaneously perform range compression on a plurality of data strings in parallel, similarly to the conventional synthetic aperture radar apparatus.

When the range compression is completed by the range compression means 1, the range-compressed data generated by the range compression means 1 is passed to the azimuth compression means 2. The azimuth compression means 2 performs compression processing in the azimuth direction by performing correlation processing between the data after range compression and the azimuth reference function. That is, data is taken out for each line in the azimuth direction, FFT is performed, and after FFT is completed for all data, range migration correction, complex multiplication, and IFFT are performed for each line, and this is applied to all data. By doing so, the azimuth compression is completed, and the first reproduced image is generated. Here, the azimuth compression means 2 may be configured to be able to simultaneously perform azimuth compression on a plurality of data strings in parallel, similarly to the conventional synthetic aperture radar apparatus.

When the first reproduced image is generated by the range compressing means 1 and the azimuth compressing means 2 as described above, the first reproduced image is passed to the frequency converting means 3.
Here, the first reproduced image is data in the time domain. The frequency conversion means 3 converts the first reproduced image in the time domain into data in the frequency domain. That is, data is extracted from the first reproduced image line by line in the range direction,
By performing a Fourier transform on this and performing this for all data, the conversion to frequency domain data is completed.

The data in the frequency domain converted by the frequency converting means 3 is passed to the scattering point number estimating means 4. Here, the data in the frequency domain passed from the frequency conversion means 3 to the scattering point number estimation means 4 may be passed at once after all the data is converted into data in the frequency domain by the frequency conversion means 3. The data may be transferred every time the conversion into frequency domain data is completed for each line in the direction.

The data in the frequency domain converted by the frequency conversion means 3 is regarded as a data string of one line in the range direction as the frequency data of the reception signal of one set of antennas, that is, the total number of azimuth points m Then, the high-resolution angle measurement algorithm is applied by the scattering point number estimating means 4, the position estimating means 6 and the reflection intensity estimating means 8 to determine the number of target scattering points,
And the position of each target scattering point and the reflection intensity are estimated to generate a second reproduced image with higher resolution.

The scattering point number estimating means 4 comprises x basic processing means 5. Upon receiving the data in the frequency domain from the frequency converting means 3, the scattering point number estimating means 4 passes a data line for one line in the desired range direction to each basic processing means 5.

Each of the basic processing means 5 independently and in parallel with respect to the received data stream of one line in the desired range direction, determines the number of target scattering points based on a high-resolution angle measurement algorithm. Make an estimate. That is, at the same time, x
A process of estimating the number of target scattering points is performed on a set of data strings for one line in the range direction.

The estimation of the number of target scattering points by each basic processing means 5 is performed as follows according to the MUSIC method, for example. First, a covariance matrix of a data string for one line in the range direction is calculated. Next, a moving average (spatial smoothing) of the calculated covariance matrix is performed to suppress the correlation of the reflected waves at each target scattering point, and an average covariance matrix is obtained. Next, eigenvalue analysis of the average covariance matrix is performed to calculate eigenvalues. Among the eigenvalues obtained in this way, the number of eigenvalues larger than the smallest eigenvalue is obtained, and this is set as the number of target scattering points.

When the estimation processing of the number of target scattering points by each basic processing means 5 is completed, the scattering point number estimating means 4 converts a data sequence for one line in a desired range direction from the unprocessed frequency domain data. It is passed to each basic processing means 5. Each basic processing means 5 again estimates the number of target scattering points based on the high-resolution angle measurement algorithm. By repeating this process until there is no unprocessed frequency domain data, processing of all frequency domain data is completed, and the number of target scattering points existing for each azimuth is estimated.

Subsequently, the position estimating means 6 estimates the positions of the individual target scattering points obtained by the scattering point number estimating means 4. Here, the processing of estimating the position of the target scattering point by the position estimating means 6 may be started after the processing of estimating the number of target scattering points by the scattering point number estimating means 4 is completed for all azimuths. May be started each time the estimation process of the number of target scattering points is completed.

The position estimating means 6 comprises y basic processing means 7
Consists of The position estimating means 6 instructs each basic processing means 7 to perform a desired azimuth processing from the azimuths for which the estimation processing of the number of target scattering points has been completed by the scattering point number estimating means 4. Each basic processing means 7 estimates the position of the target scattering point for the assigned azimuth independently and simultaneously in parallel, based on a high-resolution angle measurement algorithm. That is, at the same time, the process of estimating the position of the target scattering point is performed on y azimuths.

The estimation of the position of the target scattering point by each basic processing means 7 is performed as follows according to, for example, the MUSIC method. First, mode vector and scattering point number estimating means 4
And an estimating function obtained from the eigenvector (noise space eigenvector) corresponding to the minimum eigenvalue calculated by. Next, the scattering point number estimating means 4 is calculated from the evaluation function.
Search peaks by the number of target scattering points estimated by
The range giving this peak is defined as the position (range) of each target scattering point.

When the processing for estimating the position of the target scattering point by each basic processing means 7 is completed, the position estimating means 6 completes the processing for estimating the number of target scattering points by the scattering point number estimating means 4,
In addition, it instructs each basic processing means 7 to perform a desired azimuth processing from unprocessed azimuths. Each basic processing means 7 estimates the position of the target scattering point again based on the high-resolution angle measurement algorithm. By repeating this for all azimuths, the position of the target scattering point existing for each azimuth is estimated.

Subsequently, the reflection intensity estimating means 8 estimates the reflection intensity of each target scattering point. Here, the processing for estimating the reflection intensity of the target scattering point by the reflection intensity estimation means 8 is as follows.
The process of estimating the position of the target scattering point by the position estimating means 6 may be started after completion for all azimuths,
The process may be started each time the estimation process of the position of the target scattering point is completed for each azimuth.

The reflection intensity estimating means 8 comprises z basic processing means 9. The reflection intensity estimating means 8 instructs each basic processing means 9 to perform a desired azimuth processing from among the azimuths for which the position estimating means 6 has estimated the position of the target scattering point.

Each of the basic processing means 9 estimates the reflection intensity of the target scattering point on the assigned azimuth independently and simultaneously in parallel based on a high-resolution angle measurement algorithm. That is, at the same time, the estimation processing of the reflection intensity at the target scattering point is performed on z azimuths.

The estimation of the reflection intensity at the target scattering point by each basic processing means 9 is performed as follows according to, for example, the MUSIC method. First, the position of each target scattering point obtained by the position estimating means 6 is substituted into a mode vector for calculation. Next, from the matrix consisting of the calculated mode vectors,
Find the covariance matrix of the reflection coefficient. The diagonal term of the obtained covariance matrix is defined as the reflection intensity of each target scattering point.

When the processing for estimating the reflection intensity of the target scattering point by each basic processing means 9 is completed, the reflection intensity estimation means 8
The process of estimating the position of the target scattering point by the position estimating means 6 is completed, and each basic processing means 9 is instructed to perform a desired azimuth processing from unprocessed azimuths. Each basic processing means 9 estimates the reflection intensity of the target scattering point again based on the high-resolution angle measurement algorithm. By repeating this for all azimuths, the reflection intensity of the target scattering point existing for each azimuth is estimated.

As described above, for all azimuths, the number of target scattering points, the position of each target scattering point, and the reflection intensity are obtained for each azimuth. If an image is formed based on this result, a second reproduced image having a high resolution is generated. Further, if only the target scattering point is detected, imaging is not essential, and the obtained result may be directly used.

As described above, in the synthetic aperture radar apparatus according to the first embodiment, the number of target scattering points, the position of each target scattering point, and the reflection intensity are estimated based on the high-resolution angle measurement algorithm. Since the apparatus has the means 4, the position estimating means 6 and the reflection intensity estimating means 8, the target scattering point can be detected with a resolution higher than the resolution defined by the pulse width corresponding to the reciprocal 1 / Δf of the variation Δf of the carrier frequency of the pulse. .

The scattering point number estimating means 4, position estimating means 6 and reflection intensity estimating means 8 are constituted by a plurality of basic processing means, and the number of target scattering points for a plurality of azimuths is calculated.
Since the processing for estimating the position of each target scattering point and the reflection intensity is performed simultaneously in parallel, the processing can be performed at high speed.

In the first embodiment, the scattering point number estimating means 4, the position estimating means 6, and the reflection intensity estimating means 8 are used.
In the above, the MUSIC method was used as an example of estimating the number of target scattering points, the position of each target scattering point, and the reflection intensity, but it may be configured to use another high-resolution angle measurement algorithm. Good.

Embodiment 2 FIG. 3 is a block diagram showing a configuration of a synthetic aperture radar device according to Embodiment 2 of the present invention. In FIG. 3, reference numeral 10 denotes an image holding means for holding a first reproduced image generated in advance, and the other configuration is the same as that of the first embodiment.

In the synthetic aperture radar apparatus according to the second embodiment, based on the first reproduced image held in the image holding means 10, the frequency conversion means 3, the scattering point estimation means 4,
The number of target scattering points, the position of each target scattering point, and the reflection intensity are estimated by the position estimating means 6 and the reflection intensity estimating means 8 to generate a second reproduced image with higher resolution.

Next, the operation will be described. FIG. 4 is a diagram showing the flow of the SAR image reproduction process according to the second embodiment. Here, as in the case of the conventional SAR image reproducing process shown in FIG. 13, the first reproduced image is obtained by observing data having a two-dimensional spread in the range direction and the azimuth direction.
It is generated by compressing in the range direction and the azimuth direction by a correlation process (convolution operation) with the range reference function and the azimuth reference function. By converting this first reproduced image into the frequency domain and analyzing this frequency component, the number of target scattering points, the position of each target scattering point, and the reflection intensity are estimated, and a second reproduced image is generated. I do.

That is, the synthetic aperture radar apparatus according to the second embodiment is different from the synthetic aperture radar apparatus according to the first embodiment in that the first reproduced image generated and held is used.

First, the first reproduced image held in the image holding means 10 is input to the frequency conversion means 3. The frequency conversion means 3 converts the first reproduced image in the time domain into data in the frequency domain. That is, data is extracted line by line in the range direction from the first reproduced image, subjected to Fourier transform, and performed on all data, thereby completing the conversion to frequency domain data. The frequency domain data converted by the frequency conversion means 3 is passed to the scattering point number estimation means 4.

Thereafter, the scattering point number estimating means 4, the position estimating means 6, and the reflection intensity estimating means 8 operate similarly to the synthetic aperture radar apparatus according to the first embodiment. That is, the scattering point number estimating means 4 simultaneously uses x basic processing means 5,
The number of target scattering points existing for each azimuth is estimated based on a high-resolution angle measurement algorithm. The position estimating means 6
At the same time, the position of the target scattering point existing for each azimuth is estimated using the y basic processing means 7 based on the high-resolution angle measurement algorithm. The reflection intensity estimation means 8 simultaneously
The reflection intensity of a target scattering point existing for each azimuth is estimated using the basic processing means 9 based on a high-resolution angle measurement algorithm.

As described above, for all azimuths, the number of target scattering points, the position of each target scattering point, and the reflection intensity are obtained for each azimuth. If an image is formed based on this result, a second reproduced image having a high resolution is generated. Further, if only the target scattering point is detected, imaging is not essential, and the obtained result may be directly used.

As described above, in the synthetic aperture radar apparatus according to the second embodiment, the data is generated in advance by the correlation processing between the observation data and the range reference function and the azimuth reference function.
Based on the retained first reproduction image, the second reproduction image having a higher resolution is generated.For example, the first reproduction image is generated in the past, and the original observation data is lost. Even if the first playback image is obtained from another person and the original observation data is not available, even if there is no original observation data and only the first playback image is held A second reproduced image with higher resolution can be obtained.

Further, even if the original observation data exists, if the first reproduction image generated from the observation data is held, the trouble of generating the first reproduction image from the observation data again is omitted. Therefore, a second reproduced image with higher resolution can be obtained at high speed.

Further, if the means for generating the first reproduced image from the observation data is already possessed, a device having a similar function without any modification to those means is required. Since there is no need to develop, development costs can be reduced.

Embodiment 3 FIG. 5 is a block diagram showing a configuration of a synthetic aperture radar device according to Embodiment 3 of the present invention. In FIG. 5, reference numeral 11 denotes azimuth compression means for compressing observation data in the azimuth direction, and reference numeral 12 denotes azimuth compression data compressed in the azimuth direction by the azimuth compression means 11 in the range direction. The other configuration is the same as that of the first embodiment.

In the synthetic aperture radar apparatus according to the third embodiment, range compression is performed after azimuth compression, and conversion to the time domain in range compression, ie, inverse Fourier transform, is omitted. The number of target scattering points, the position of each target scattering point, and the reflection intensity are estimated by the estimating means 6 and the reflection intensity estimating means 8, and a method of generating a second reproduced image with higher resolution is adopted.

Next, the operation will be described. FIG. 6 is a diagram showing the flow of the SAR image reproduction process according to the present embodiment. Basically, first, as in the synthetic aperture radar device according to the first embodiment, the two directions of the range direction and the azimuth direction are used.
A first reproduced image is generated by compressing the observation data having a spread in dimension in the range direction and the azimuth direction by a correlation process (convolution operation) with the range reference function and the azimuth reference function, The number of target scattering points, the position of each target scattering point, and the reflection intensity are estimated by converting one reproduced image into the frequency domain and analyzing the frequency components to generate a second reproduced image.

Here, since the first reproduced image is generated by the correlation processing with the range reference function and the azimuth reference function, there is no problem if the correlation processing with either reference function is performed first. Therefore, in the procedure for generating the first reproduced image, the procedure of the range compression and the azimuth compression is reversed,
After azimuth compression is performed first, then range compression is performed.

In this case, first, in range compression, F
After conversion to the frequency domain in the range direction by FT, complex multiplication is performed, and the result is the frequency domain.
The data is converted into data in the time domain by T, and then converted again into the frequency domain in the range direction. That is, by omitting the IFFT in the range compression, it is possible to omit the conversion to the next frequency domain.

Accordingly, in the synthetic aperture radar apparatus according to the third embodiment, first, azimuth compression is performed, and then range compression is performed. At this time, the conversion into the time domain is performed.
FFT is omitted. By analyzing the frequency components for the first reproduced image in the frequency domain obtained in this way, the number of target scattering points, the position of each target scattering point, and the reflection intensity are estimated. Generate

As described above, the synthetic aperture radar apparatus according to the third embodiment is different from the first embodiment in that range compression is performed after azimuth compression, and IFFT and conversion to the next frequency domain in range compression are omitted. Is different from the synthetic aperture radar device.

First, the observation data is stored in the azimuth compression means 1.
1 is input. The azimuth compression means 11 performs a correlation process between the observation data and the azimuth reference function,
A compression process in the azimuth direction is performed. That is, data is taken out for each line in the azimuth direction, FFT is performed, and after FFT is completed for all data, range migration correction, complex multiplication, and IFFT are performed for each line, and this is applied to all data. To complete the azimuth compression.

When the azimuth compression is completed by the azimuth compression means 11, the azimuth compressed data generated by the azimuth compression means 11 is passed to the range compression means 12. The range compression means 12 performs a compression process in the range direction by performing a correlation process between the data after the azimuth compression and the range reference function. At this time, the conversion to the time domain by the IFFT is omitted. That is, 1 in the range direction
By extracting data for each line, performing FFT and complex multiplication, and performing this for all data, range compression is completed and a first reproduced image in the frequency domain is generated.

As described above, the first reproduced image in the generated frequency domain is passed to the scattering point number estimating means 4. Here, the first reproduced image in the frequency domain passed from the range compression unit 12 to the scattering point number estimation unit 4 may be passed at once after the range compression unit 12 compresses all the data in the range. The data may be transferred every time the range compression is completed for each line in the direction.

Thereafter, the scattering point number estimating means 4, the position estimating means 6, and the reflection intensity estimating means 8 operate similarly to the synthetic aperture radar apparatus according to the first embodiment. That is, the scattering point number estimating means 4 simultaneously uses x basic processing means 5,
The number of target scattering points existing for each azimuth is estimated based on a high-resolution angle measurement algorithm. The position estimating means 6
At the same time, the position of the target scattering point existing for each azimuth is estimated using the y basic processing means 7 based on the high-resolution angle measurement algorithm. The reflection intensity estimation means 8 simultaneously
The reflection intensity of a target scattering point existing for each azimuth is estimated using the basic processing means 9 based on a high-resolution angle measurement algorithm.

As described above, for all azimuths, the number of target scattering points, the position of each target scattering point, and the reflection intensity are obtained for each azimuth. If an image is formed based on this result, a second reproduced image having a high resolution is generated. Further, if only the target scattering point is detected, imaging is not essential, and the obtained result may be directly used.

As described above, in the synthetic aperture radar apparatus according to the third embodiment, range compression is performed after azimuth compression, and IFFT and conversion to the next frequency domain in range compression are omitted. A second reproduced image with high resolution can be obtained.

Embodiment 4 FIG. 7 is a block diagram showing a configuration of a synthetic aperture radar device according to Embodiment 4 of the present invention. In FIG. 7, reference numeral 13 denotes time conversion means for converting the first reproduced image in the frequency domain generated by the range compression means 12 into the time domain, and the other configuration is the same as that of the third embodiment.

In the synthetic aperture radar apparatus according to the fourth embodiment, by adding the time conversion means 13 to the synthetic aperture radar apparatus according to the third embodiment, the first reproduction having the same resolution as the conventional synthetic aperture radar apparatus is performed. A method of generating an image and a second reproduced image with higher resolution is adopted.

Next, the operation will be described. FIG. 8 is a diagram showing the flow of the SAR image reproduction process according to the fourth embodiment. The result of the complex multiplication in the range compression, that is, the first reproduced image in the frequency domain is converted into the time domain by IFFT to generate the first reproduced image, and by analyzing this frequency component, the target scattering point number,
And the position of each target scattering point and the reflection intensity are estimated to generate a second reproduced image.

First, the observation data is stored in the azimuth compression means 1.
1 is input. The azimuth compression means 11 performs a correlation process between the observation data and the azimuth reference function,
A compression process in the azimuth direction is performed. That is, data is taken out for each line in the azimuth direction, FFT is performed, and after FFT is completed for all data, range migration correction, complex multiplication, and IFFT are performed for each line, and this is applied to all data. To complete the azimuth compression.

When the azimuth compression is completed by the azimuth compression means 11, the azimuth compressed data generated by the azimuth compression means 11 is passed to the range compression means 12. The range compression means 12 performs a compression process in the range direction by performing a correlation process between the data after the azimuth compression and the range reference function. At this time, the conversion to the time domain by the IFFT is omitted. That is, 1 in the range direction
By extracting data for each line, performing FFT and complex multiplication, and performing this for all data, range compression is completed and a first reproduced image in the frequency domain is generated.

As described above, the generated first reproduced image in the frequency domain is passed to the time converting means 13 and the scattering point number estimating means 4. Here, range compression means 1
The first reproduced image in the frequency domain, which is passed to the time converting means 13 and the scattering point number estimating means 4 from
2, the data may be delivered at once after range compression, or may be delivered every time range compression is completed for each line in each range direction.

The time conversion means 13 includes the range compression means 1
2 receives the first reproduced image in the frequency domain from IF
It is converted to the time domain in the range direction by FT. That is, data is taken out line by line in the range direction and
By performing FT and performing this for all data, conversion to the time domain is completed, and a first reproduced image is generated.

On the other hand, the scattering point number estimating means 4 and the subsequent position estimating means 6 and the reflection intensity estimating means 8 operate in the same manner as the synthetic aperture radar apparatus according to the first embodiment, and produce the second reproduced image with high resolution. Generate. That is, the scattering point number estimating means 4 estimates the number of target scattering points existing for each azimuth using x basic processing means 5 at the same time based on the high-resolution angle measurement algorithm. The position estimating means 6 simultaneously estimates the position of the target scattering point for each azimuth based on the high-resolution angle measurement algorithm using the y basic processing means 7. The reflection intensity estimating means 8 simultaneously uses the z basic processing means 9 to estimate the reflection intensity of a target scattering point existing for each azimuth based on a high-resolution angle measurement algorithm.

As described above, for all azimuths, the number of target scattering points, the position of each target scattering point, and the reflection intensity are obtained for each azimuth. If an image is formed based on this result, a second reproduced image having a high resolution is generated. Further, if only the target scattering point is detected, imaging is not essential, and the obtained result may be directly used.

As described above, in the synthetic aperture radar according to the fourth embodiment, since the time conversion means 13 is provided, a first reproduced image having the same resolution as that of the conventional synthetic aperture radar can be generated.

In parallel with this, the generation of the second reproduced image having a high resolution is performed without performing the IFFT in the range compression and the conversion to the next frequency domain, so that the second reproduced image is generated at a higher speed and with a higher resolution. A high second reproduced image can be obtained.

Embodiment 5 FIG. 9 is a block diagram showing a configuration of a synthetic aperture radar device according to Embodiment 5 of the present invention. In FIG. 9, reference numeral 14 denotes a scattering point number estimation unit 4.
Processing load balancing means for adjusting the target number of scattering points processed by each basic processing means 7 of the position estimating means 6 and each basic processing means 9 of the reflection intensity estimating means 8 according to the target number of scattering points for each azimuth estimated in The other configuration is the same as that of the first embodiment.

In the synthetic aperture radar according to the fifth embodiment, the processing load balancing means 14 causes the position estimating means 6
The number of target scattering points to be processed by each of the basic processing means 7 and the basic processing means 9 of the reflection intensity estimating means 8 is adjusted, and a method of balancing processing loads is adopted.

Next, the operation will be described. First, a first reproduced image is generated from the observation data received by the range compression unit 1 and the azimuth compression unit 2. This procedure and operation are the same as those of the synthetic aperture radar device according to the first embodiment. That is, the range compression means 1 performs a correlation process between the observation data and the range reference function to perform a compression process in the range direction, and the azimuth compression means 2 generates the range-compressed data generated by the range compression means 1 and the azimuth reference function. And a compression process in the azimuth direction is performed to generate a first reproduced image.

Next, the first reproduced image is output to the frequency conversion means 3.
To be converted into frequency domain data. This procedure and operation are the same as those of the synthetic aperture radar device according to the first embodiment.

The frequency domain data converted by the frequency conversion means 3 is passed to the scattering point number estimation means 4. The scattering point number estimating means 4 simultaneously uses x number of basic processing means 5 to estimate the number of target scattering points existing for each azimuth based on a high-resolution angle measurement algorithm. This procedure,
The operation is the same as that of the synthetic aperture radar device according to the first embodiment.

When the number of target scattering points existing for each azimuth is estimated by the number-of-scattering-points estimating means 4, the processing load balancing means 14 immediately proceeds to the basic processing means 7 and the reflection intensity estimating means 8 of the position estimating means 6. The azimuth to be assigned to each of the basic processing means 9 is determined. Here, the processing of the processing load balancing means 14 may be started after the processing of estimating the number of target scattering points by the scattering point number estimating means 4 is completed for all azimuths. May be started each time the estimating process is completed.

In the processing load balancing means 14, for the azimuths for which the number of target scattering points has been estimated by the scattering point number estimating means 4, the basic processing means 7 of the position estimating means 6 to process the azimuth and the reflection Each basic processing means 9 of the intensity estimating means 8 is determined.

For example, for an azimuth having a large number of target scattering points, more basic processing means 7 of the position estimating means 6 are used.
And the respective basic processing means 9 of the reflection intensity estimating means 8 may be assigned. The position of the target scattering point and the reflection intensity in this azimuth can be estimated at high speed.

Each basic processing means 7 of the position estimating means 6
The total number of target scattering points to be processed by each of the basic processing units 9 of the reflection intensity estimating unit 8 may be allocated as much as possible. The processing time of each basic processing means 7 of the position estimating means 6 and each basic processing means 9 of the reflection intensity estimating means 8 is as follows:
It is proportional to the total number of target scattering points to be processed, and the final processing result, that is, the processing time until the second reproduced image is obtained, is the basic processing means 7 of the position estimating means 6 having the longest processing time. Since the processing time of the basic processing means 9 of the reflection intensity estimating means 8 is determined, the total number of target scattering points to be processed by each basic processing means 7 of the position estimating means 6 and each basic processing means 9 of the reflection intensity estimating means 8 is the same. Then, the processing can be completed at the earliest, that is, a second reproduced image can be obtained.

Subsequently, the position estimating means 6 estimates the positions of the individual target scattering points obtained by the scattering point number estimating means 4. The position estimating means 6 instructs each basic processing means 7 to perform a desired azimuth processing based on the assignment determined by the processing load balancing means 14. here,
The process of estimating the position of the target scattering point by the position estimating means 6 is as follows.
The processing may be started after all the azimuth has been assigned to the basic processing means 7 by the processing load balancing means 14, or may be started as soon as it is determined.

Subsequently, the reflection intensity estimation means 8 estimates the reflection intensity of each target scattering point. The reflection intensity estimating means 8 selects the processing load balancing means 14 from the azimuths for which the position estimating means 6 has estimated the position of the target scattering point.
Each basic processing means 9 is instructed to perform a desired azimuth processing based on the assignment determined by the above. Here, the processing for estimating the reflection intensity of the target scattering point by the reflection intensity estimating means 8 may be started after all the azimuths have been assigned to the basic processing means 9 by the processing load balancing means 14, and may be determined at any time. It may be started as soon as possible.

As described above, for all azimuths, the number of target scattering points, the position of each target scattering point, and the reflection intensity are obtained for each azimuth. If an image is formed based on this result, a second reproduced image having a high resolution is generated. Further, if only the target scattering point is detected, imaging is not essential, and the obtained result may be directly used.

As described above, in the synthetic aperture radar according to the fifth embodiment, the processing load balancing means 14 controls the basic processing means 7 and the reflection intensity estimating means 8 of the position estimating means 6.
Since the number of target scattering points to be processed by each of the basic processing means 9 is adjusted, it is possible to eliminate bias in processing time and obtain a second reproduced image at high speed.

In the above description, a case has been described in which the processing load balancing means 14 is added to the synthetic aperture radar apparatus according to the first embodiment. However, the processing load balancing means 14 is added to the synthetic aperture radar apparatus according to the other embodiments. Obviously, the same effect can be obtained when added.

Embodiment 6 FIG. 10 is a block diagram showing a configuration of a synthetic aperture radar device according to Embodiment 6 of the present invention. In FIG. 10, reference numeral 15 denotes a scattering point number prediction unit for predicting the number of target scattering points that will be estimated by the scattering point number estimation unit 4 from the first reproduced image generated by the azimuth compression unit 2. Is the structure of the fifth embodiment.
Is the same as

In the synthetic aperture radar apparatus according to the sixth embodiment, the processing load balancing means 14 controls the basic processing means 7 of the position estimating means 6 and the reflection based on the predicted value of the target scattering point number given to the scattering point number estimating means 15. Strength estimation means 8
The target number of scattering points to be processed by each of the basic processing means 9 is adjusted,
Use a method that balances the processing load.

Next, the operation will be described. First, a first reproduced image is generated from the observation data received by the range compression unit 1 and the azimuth compression unit 2. This procedure and operation are the same as those of the synthetic aperture radar device according to the first embodiment. That is, the range compression means 1 performs a correlation process between the observation data and the range reference function to perform a compression process in the range direction, and the azimuth compression means 2 generates the range-compressed data generated by the range compression means 1 and the azimuth reference function. And a compression process in the azimuth direction is performed to generate a first reproduced image.

Next, the first reproduced image is output to the frequency conversion unit 3.
And the scattering point number prediction means 15. In the frequency conversion unit 3, the first reproduced image is converted into data in the frequency domain, and is passed to the scattering point number estimation unit 4. This procedure and operation are the same as those of the synthetic aperture radar device according to the first embodiment.

On the other hand, the scattering point number estimating means 15 converts the first reproduced image from the first reproduced image in parallel with the processing by the frequency converting means 3.
For each azimuth, a process of estimating the number of target scattering points that will be estimated by the scattering point number estimating means 4 is performed.

For example, when the reflection intensity of the partial area obtained from the first reproduced image is equal to or higher than a certain level, the scattering point number estimating means 15 may predict that the target scattering point exists in the partial area. . Alternatively, the number of target scattering points existing in the partial area may be predicted according to the level of the reflection intensity of the partial area. Further, the number of existing target scattering points may be predicted according to the distribution of the reflection intensity obtained from the first reproduced image.

The predicted value of the target number of scattering points for each azimuth predicted by the number-of-scattering-points predicting means 15 is passed to the processing load balancing means 14. The processing load balancing means 14 immediately determines the azimuth to be assigned to each basic processing means 7 of the position estimating means 6 and each basic processing means 9 of the reflection intensity estimating means 8.

On the other hand, the data in the frequency domain converted by the frequency converting means 3 is passed to the scattering point number estimating means 4. The scattering point number estimating means 4 simultaneously uses x basic processing means 5 to estimate the number of target scattering points existing for each azimuth based on a high-resolution angle measurement algorithm.

Subsequently, the position estimating means 6 estimates the positions of the individual target scattering points obtained by the scattering point number estimating means 4. The position estimating means 6 performs a desired azimuth processing based on the allocation determined by the processing load balancing means 14 from the azimuths for which the estimation processing of the number of target scattering points by the scattering point number estimating means 4 is completed. Each basic processing means 7 is instructed, and each basic processing means 7 estimates the position of the target scattering point.

Subsequently, the reflection intensity estimation means 8 estimates the reflection intensity of each target scattering point. The reflection intensity estimating means 8 selects the processing load balancing means 14 from the azimuths for which the position estimating means 6 has estimated the position of the target scattering point.
Is instructed to perform a desired azimuth processing based on the assignment determined by the above, and the reflection intensity of the target scattering point is estimated by each basic processing means 9.

As described above, for all azimuths, the number of target scattering points, the position of each target scattering point, and the reflection intensity are obtained for each azimuth. If an image is formed based on this result, a second reproduced image having a high resolution is generated. Further, if only the target scattering point is detected, imaging is not essential, and the obtained result may be directly used.

As described above, in the synthetic aperture radar according to the sixth embodiment, the prediction of the target number of scattering points by the number-of-scattering-points predicting means 15 and the basics of the position estimating means 6 of the processing load balancing means 14 based on the predicted value are performed. Since the determination of the azimuth to be assigned to each basic processing means 9 of the processing means 7 and the reflection intensity estimation means 8 is performed in parallel with the frequency conversion by the frequency conversion means 3 and the estimation of the target number of scattering points by the number of scattering points estimation means 4, The bias of the processing time can be eliminated without the processing delay by the load balancing means 14, and the second reproduced image can be obtained at high speed.

The scattering point number predicting means 15 estimates the number of target scattering points estimated by the scattering point number estimating means 4, the position of the target scattering point estimated by the position estimating means 6, and the reflection intensity estimating means 8. Obtain the reflection intensity at the target scattering point,
The prediction method may be corrected so as to obtain a more correct predicted value from these results. The prediction accuracy can be improved, and the bias of the processing time can be eliminated.

In the above description, a case has been described in which the processing load balancing means 14 and the scattering point number predicting means 15 are added to the synthetic aperture radar apparatus according to the first embodiment, but the same applies to the synthetic aperture radar apparatus according to the other embodiments. It is.

Seventh Embodiment FIG. 11 is a block diagram showing a configuration of a synthetic aperture radar device according to a seventh embodiment of the present invention. In FIG. 11, reference numeral 16 denotes an azimuth to be processed by the scattering point number estimating means 4, the position estimating means 6, and the reflection intensity estimating means 8 in accordance with the prediction result of the target scattering point number obtained by the scattering point number estimating means 15, and a processing order thereof. , And the other configuration is the same as that of the sixth embodiment.

In the synthetic aperture radar apparatus according to the seventh embodiment, the scattered point number estimating means 4, the position estimating means 6 and the reflection intensity estimating means 8 process based on the predicted value of the target scattered point number given to the scattered point number estimating means 15. Azimuth and the method of controlling the processing order.

Next, the operation will be described. First, a first reproduced image is generated from the observation data received by the range compression unit 1 and the azimuth compression unit 2. This procedure and operation are the same as those of the synthetic aperture radar device according to the first embodiment. That is, the range compression means 1 performs a correlation process between the observation data and the range reference function to perform a compression process in the range direction, and the azimuth compression means 2 generates the range-compressed data generated by the range compression means 1 and the azimuth reference function. And a compression process in the azimuth direction is performed to generate a first reproduced image.

Next, the first reproduced image is output from the frequency conversion means 3.
And the scattering point number prediction means 15. In the frequency conversion unit 3, the first reproduced image is converted into data in the frequency domain, and is passed to the scattering point number estimation unit 4. This procedure and operation are the same as those of the synthetic aperture radar device according to the first embodiment.

On the other hand, in parallel with the processing by the frequency converting means 3, the scattering point number predicting means 15
For each azimuth, a process of predicting the number of target scattering points is performed.

Next, the processing load control means 16 calculates the number of scattering points estimating means 4, the position estimating means 6, and the reflection intensity based on the predicted value of the target number of scattering points for each azimuth predicted by the number of scattering points predicting means 15. The azimuth to be processed by the estimating means 8 and the processing order thereof are determined.

For example, in the processing load control means 16, for the azimuth for which the target number of scattering points is 0, that is, the target scattering point is predicted not to exist, the number of scattering points estimating means 4, the position estimating means 6, and the reflection intensity estimating means 8 may be controlled so as not to perform the processing. Alternatively, priorities are determined according to the number and distribution of target scattering points, for example, by giving a high priority to an azimuth where many target scattering points are present or to a portion where the target scattering points are dense. Alternatively, control may be performed such that processing is performed first on a higher priority order.

Subsequently, the processing load balancing means 14 refers to the control information determined by the processing load control means 16 and calculates the position from the predicted value of the target number of scattering points for each azimuth predicted by the number of scattering points prediction means 15. Each basic processing means 7 of the estimating means 6
And the azimuth to be assigned to each basic processing means 9 of the reflection intensity estimating means 8 is determined.

On the other hand, the frequency domain data converted by the frequency conversion means 3 is passed to the scattering point number estimation means 4. The scattering point number estimating unit 4 estimates the number of target scattering points existing for each azimuth using the x basic processing units 5 based on the control information determined by the processing load control unit 16.

Subsequently, the position estimating means 6 compares the control information determined by the processing load control means 16 with the processing load balancing means 1.
Based on the assignment information determined in step 4, the position of each target scattering point obtained by the scattering point number estimating unit 4 is estimated using y basic processing units 7 at the same time.

Subsequently, the reflection intensity estimating means 8 simultaneously uses the z basic processing means 9 based on the control information determined by the processing load control means 16 and the assignment information determined by the processing load balancing means 14. , The reflection intensity of each target scattering point obtained by the scattering point number estimating means 4 is estimated.

As described above, for all azimuths, the number of target scattering points, the position of each target scattering point, and the reflection intensity are obtained for each azimuth. If an image is formed based on this result, a second reproduced image having a high resolution is generated. Further, if only the target scattering point is detected, imaging is not essential, and the obtained result may be directly used.

As described above, in the synthetic aperture radar apparatus according to the seventh embodiment, since the azimuth to be processed is controlled by the processing load control means 16, processing time for unnecessary portions can be reduced, and the second reproduced image can be reproduced at high speed. Can be obtained.

Since the processing order of the azimuth is controlled by the processing load control means 16, the second reproduced image of the important part can be obtained at higher speed.

In the above description, the processing load control means 16
Does not control the processing in the frequency conversion means 3, but may control the azimuth to be processed in the frequency conversion means 3 and the processing order.

In the above description, a case has been described in which the processing load balancing means 14 and the scattering point number predicting means 15 and 16 are added to the synthetic aperture radar apparatus according to the first embodiment.
The same applies to a synthetic aperture radar device according to another embodiment.

[0138]

As described above, according to the present invention, there are provided scattering point number estimating means for estimating the number of target scattering points, the position of each target scattering point and the reflection intensity, the position estimating means and the reflection intensity estimating means. Therefore, the change amount Δf of the carrier frequency of the pulse
The target scattering point can be detected with a resolution equal to or greater than the resolution defined by the pulse width corresponding to the reciprocal 1 / Δf. Further, the scattering point number estimating means, the position estimating means and the reflection intensity estimating means are respectively constituted by a plurality of basic processing means, and the number of target scattering points for a plurality of azimuths, the position of each target scattering point and the reflection intensity are estimated. Since the processing is performed simultaneously in parallel, the processing can be performed at high speed.

A range compression means, an azimuth compression means for compressing the data after range compression in the azimuth direction,
Frequency conversion means for converting the first reproduced image generated by the azimuth compression means into a frequency domain,
Based on the frequency domain data converted by the frequency conversion means, the scattering point number estimating means, the position estimating means, and the reflection intensity estimating means generate the second reproduced image. Based on the frequency domain data converted into the domain, the number of target scattering points, the position of each target scattering point and the reflection intensity can be estimated, and a second reproduced image with higher resolution can be obtained. it can.

[0140] Further, an image holding means for storing the first reproduced image is provided, and the second reproduced image having higher resolution is generated based on the held first reproduced image. If you generate one playback image and lose the original observation data, or obtain the first playback image from others,
Even when the original observation data is not available, for example, when there is no original observation data and only the first reproduction image is held, the second reproduction image with higher resolution can be obtained.

Further, by performing range compression after azimuth compression and omitting IFFT and conversion to the next frequency domain in range compression, it is possible to obtain a second reproduced image with higher resolution at higher speed. it can.

Further, since time conversion means for converting the data after range compression in the frequency domain generated by the range compression means to the time domain to generate a reproduced image is provided, the resolution is the same as that of the conventional synthetic aperture radar apparatus. The first reproduced image can be generated. In parallel with this, the generation of the second reproduced image with high resolution is performed without performing the IFFT in the range compression and the conversion to the next frequency region, so that the higher speed is achieved. In addition, a second reproduced image with high resolution can be obtained.

Further, the processing load balancing means adjusts the number of target scattering points to be processed by each basic processing means of the position estimating means and each basic processing means of the reflection intensity estimating means according to the number of target scattering points. Can be eliminated, and the second reproduced image can be obtained at high speed.

Further, the apparatus further comprises target scattering point number predicting means for predicting the number of target scattering points from the first reproduced image, and the processing load balancing means selects the number of target scattering points according to the number of target scattering points obtained by the target scattering point number predicting means. Since the data sequence given to each of the basic processing means of the position estimating means and each of the basic processing means of the reflection intensity estimating means is adjusted, it is possible to eliminate the bias of the processing time without processing delay by the processing load balancing means. Thus, the second reproduced image can be obtained at high speed.

When the reflection intensity of the partial area obtained from the first reproduced image is higher than a certain level, it is predicted that a target scattering point exists in the partial area, or the reflection intensity of this partial area is According to the level, the number of target scattering points existing in the partial area is predicted, or the number of target scattering points existing is predicted according to the distribution of the reflection intensity obtained from the first reproduced image. The scattering point number estimating means predicts the number of target scattering points that will be estimated by the scattering point number estimating means for each azimuth from the first reproduced image in parallel with the processing by the frequency conversion means. Can be performed.

The scattering point number estimating means calculates the number of target scattering points estimated by the scattering point number estimating means, the position of the target scattering point estimated by the position estimating means, and the target scattering point estimated by the reflection intensity estimating means. The prediction method may be corrected so as to obtain the reflection intensity and obtain a more accurate prediction value from these results, thereby improving the prediction accuracy and eliminating the bias in the processing time.

Further, the processing load balancing means assigns a large number of the basic processing means of the position estimating means and the reflection intensity estimating means to the data string having a large number of target scattering points, so that the second processing can be performed at high speed. A reproduced image can be obtained.

Further, the data load is allocated by the processing load balancing means so that the target scattering points to be processed by the respective basic processing means of the position estimating means and the reflection intensity estimating means are the same. Can be obtained.

In addition, the processing load control means, in accordance with the target number of scattered points obtained by the scattered point number estimating means, obtains a data string or a plurality of data strings to be processed by the scattered point number estimating means, position estimating means and reflection intensity estimating means. Since the processing order is controlled, the second reproduced image of the important part can be obtained at higher speed.

The processing load control means controls the scattering point number estimating means, the position estimating means and the reflection intensity estimating means so as not to process the data sequence predicted by the scattering point number estimating means to have no target scattering point. As a result, the processing time for unnecessary portions can be reduced, and the second reproduced image can be obtained at high speed.

Further, the processing load control means determines the priority of the data sequence to be processed in accordance with the number and distribution of the target scattering points predicted by the scattering point number predicting means, and performs the processing in descending order of the priority. Since the scattering point number estimating means, the position estimating means, and the reflection intensity estimating means are controlled as described above, the second reproduced image can be obtained at high speed.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a synthetic aperture radar device according to Embodiment 1 of the present invention.

FIG. 2 is a diagram showing a flow of an SAR image reproduction process according to the first embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of a synthetic aperture radar device according to Embodiment 2 of the present invention.

FIG. 4 is a diagram showing a flow of an SAR image reproduction process according to Embodiment 2 of the present invention;

FIG. 5 is a block diagram showing a configuration of a synthetic aperture radar device according to Embodiment 3 of the present invention.

FIG. 6 is a diagram showing a flow of an SAR image reproduction process according to Embodiment 3 of the present invention;

FIG. 7 is a block diagram showing a configuration of a synthetic aperture radar device according to Embodiment 4 of the present invention.

FIG. 8 is a diagram showing a flow of an SAR image reproduction process according to Embodiment 4 of the present invention;

FIG. 9 is a block diagram showing a configuration of a synthetic aperture radar device according to Embodiment 5 of the present invention.

FIG. 10 is a block diagram showing a configuration of a synthetic aperture radar device according to Embodiment 6 of the present invention.

FIG. 11 is a block diagram showing a configuration of a synthetic aperture radar device according to Embodiment 7 of the present invention.

FIG. 12 is a block diagram illustrating a configuration of a synthetic aperture radar device according to a conventional example.

FIG. 13 is a diagram showing a flow of SAR image reproduction processing according to a conventional example.

FIG. 14 illustrates the range coverage correction according to the conventional example and the present invention, in which the same range data distributed on a quadratic curve after performing FFT in the azimuth direction;
FIG. 9 is an explanatory diagram in which the data is resampled (interpolated and picked up) on a straight line.

FIG. 15 is an explanatory diagram of observation data composed of n data in the range direction and m data in the azimuth direction.

FIG. 16 is an explanatory diagram showing an example in which n data in the range direction and (m / N) data in the azimuth direction are input to the range compression processor 17 of FIG. 12;

FIG. 17 shows the azimuth compression processor 18 of FIG.
(N / M) pieces in the range direction and m in the azimuth direction
FIG. 6 is an explanatory diagram showing an example in which pieces of data are input.

[Explanation of symbols]

1,12 range compression means, 2,11 azimuth compression means, 3 frequency conversion means, 4 scattering point estimation means, 5,
7, 9 basic processing means, 6 position estimation means, 8 reflection intensity estimation means, 10 image holding means, 13 time conversion means,
14 processing load balancing means, 15 scattering point prediction means, 1
6 Processing load control means.

Claims (17)

[Claims] 1. Scattering point number estimating means for estimating the number of target scattering points included in received observation data; position estimating means for estimating the position of each target scattering point estimated by the scattering point number estimating means; Reflection intensity estimating means for estimating the reflection intensity of each target scattering point estimated by the scattering point number estimating means, wherein the scattering point number estimating means, the position estimating means, and the reflection intensity estimating means each comprise a plurality of A synthetic aperture radar device comprising a plurality of basic processing means for simultaneously processing data strings in parallel. 2. Range compression means for compressing observation data in the range direction, azimuth compression means for compressing the range-compressed data compressed in the range direction by the range compression means in the azimuth direction, and azimuth compression means Frequency conversion means for converting the generated first reproduced image into a frequency domain, based on the data in the frequency domain converted by the frequency conversion means, the scattering point number estimation means, the position estimation means and the The synthetic aperture radar apparatus according to claim 1, wherein the second reproduced image is generated by the reflection intensity estimating means. 3. An image storing means for storing a first reproduced image generated by the range compressing means and the azimuth compressing means, wherein the first reproduced image is stored in the image storing means in advance. 3. The synthetic aperture radar apparatus according to claim 2, wherein a second reproduced image is generated by the frequency conversion unit, the scattering point number estimation unit, the position estimation unit, and the reflection intensity estimation unit. 4. An azimuth compression means for compressing observation data in the azimuth direction, and a range compression for compressing the azimuth-compressed data compressed in the azimuth direction by the azimuth compression means in the range direction and outputting the data in the frequency domain. Means, further based on the range-compressed data in the frequency domain generated by the range compression means, the scattering point number estimation means,
The synthetic aperture radar apparatus according to claim 1, wherein a reproduced image is generated by the position estimating unit and the reflection intensity estimating unit. 5. The apparatus according to claim 4, further comprising time conversion means for converting the data after range compression in the frequency domain generated by said range compression means into a time domain to generate a reproduced image. Synthetic aperture radar device. 6. A data sequence to be given to each of the basic processing means so that the processing loads of the basic processing means constituting the position estimating means and the reflection intensity estimating means are balanced according to the number of target scattering points. 6. The synthetic aperture radar device according to claim 1, further comprising a processing load balancing means for adjusting. 7. The processing load balancing means provides each basic processing means constituting the position estimating means and the reflection intensity estimating means in accordance with the number of target scattering points estimated by the scattering point number estimating means. The synthetic aperture radar device according to claim 6, wherein the data sequence is adjusted. 8. A scatter point number predicting means for predicting the number of target scatter points based on the first reproduced image generated by the range compressing means and the azimuth compressing means, wherein the processing load balancing means comprises: The data sequence given to each of the basic processing units constituting the position estimating unit and the reflection intensity estimating unit is adjusted according to the number of target scattering points obtained by the point estimating unit. The synthetic aperture radar device as described in the above. 9. The scattered point number predicting unit predicts that a target scattered point is present when the reflection intensity of a partial area obtained from a first reproduced image is equal to or higher than a certain level. Synthetic aperture radar device according to 1. 10. The scattered point number predicting means predicts the number of target scattered points included in a partial area according to a certain level of reflection intensity of the partial area obtained from a first reproduced image. The synthetic aperture radar device according to claim 8, wherein 11. The combination according to claim 8, wherein the scattering point number prediction unit predicts the number of existing target scattering points according to the distribution of the reflection intensity obtained from the first reproduced image. Aperture radar device. 12. The scattering point number estimating unit estimates the number of target scattering points estimated by the scattering point number estimating unit, the position of the target scattering point estimated by the position estimating unit, and the reflection intensity estimating unit. 12. The method according to claim 8, wherein the reflection intensity at the target scattering point is obtained, and the prediction method is corrected so as to obtain a more accurate prediction value from the results.
A synthetic aperture radar device according to any one of the above. 13. The processing load balancing unit assigns a large number of basic processing units of the position estimating unit and the reflection intensity estimating unit to a data string having a large number of target scattering points. 13. The synthetic aperture radar device according to any one of 6 to 12. 14. The processing load balancing unit assigns a data string so that the number of target scattering points to be processed by each of the basic processing units of the position estimation unit and the reflection intensity estimation unit is the same. Item 13. The synthetic aperture radar device according to any one of Items 6 to 12. 15. A data sequence to be processed by the scattering point number estimating means, the position estimating means, and the reflection intensity estimating means, and a processing order of a plurality of data strings in accordance with the target number of scattering points obtained by the scattering point number estimating means. The synthetic aperture radar device according to any one of claims 8 to 14, further comprising a processing load control means for controlling the processing load. 16. The scattered point number estimating means, the position estimating means, and the reflection intensity, so that the processing load control means does not process a data sequence predicted as having no target scattered point by the scattered point number estimating means. The synthetic aperture radar device according to claim 15, wherein the estimating means is controlled. 17. The processing load control means determines a priority order of a data sequence to be processed according to the number and distribution of target scattering points predicted by the scattering point number prediction means, and 17. The synthetic aperture radar device according to claim 15, wherein the scattering point number estimating unit, the position estimating unit, and the reflection intensity estimating unit are controlled so as to perform processing.