CN109975804B - Multi-platform constellation SAR fusion coherent imaging method - Google Patents
Multi-platform constellation SAR fusion coherent imaging method Download PDFInfo
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- CN109975804B CN109975804B CN201910161386.7A CN201910161386A CN109975804B CN 109975804 B CN109975804 B CN 109975804B CN 201910161386 A CN201910161386 A CN 201910161386A CN 109975804 B CN109975804 B CN 109975804B
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- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
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- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
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Abstract
The invention provides a multi-platform constellation SAR fusion coherent imaging method, which comprises the following steps: determining a noise covariance matrix between each platform according to echo data received by a plurality of platforms; constructing a multi-platform azimuth fuzzy suppression filter, and converting multi-channel fuzzy data into single-channel azimuth non-fuzzy data; and imaging the single-channel non-fuzzy data by adopting a compressed sensing method to obtain a multi-platform constellation SAR azimuth fuzzy suppression imaging result. According to the multi-platform constellation SAR fusion coherent imaging method provided by the invention, a mode of weighting a plurality of platform data is adopted, azimuth ambiguity is effectively inhibited, the problem of azimuth ambiguity in the process of realizing wide swath imaging of a single platform is solved, a compressed sensing technology is adopted, single-channel azimuth unambiguous data is imaged, side lobes can be effectively inhibited, and the imaging quality is ensured.
Description
Technical Field
The invention relates to the technical field of radar imaging, in particular to a multi-platform constellation SAR fusion coherent imaging method.
Background
The azimuth geometric resolution and the range mapping bandwidth are two important technical indexes for measuring the SAR system. Due to the nyquist sampling theorem, it is difficult to simultaneously realize high resolution in the azimuth direction and wide mapping band in the distance direction, and with the rapid development of microsatellite technology in recent years, the multi-platform constellation SAR imaging method is also an important technical approach for realizing the high resolution and wide amplitude capability of SAR in the future. However, in a single platform, in order to realize a wide swath, a lower PRF is adopted, so that the azimuth direction has a certain azimuth ambiguity.
Disclosure of Invention
The invention provides a multi-platform constellation SAR fusion coherent imaging method, aiming at overcoming the technical defect that azimuth direction has certain azimuth ambiguity in the process of realizing wide swath imaging by using the existing single platform.
In order to solve the technical problems, the technical scheme of the invention is as follows:
a multi-platform constellation SAR fusion coherent imaging method comprises the following steps:
s1: determining a noise covariance matrix between each platform according to echo data received by a plurality of platforms;
s2: constructing a multi-platform azimuth fuzzy suppression filter, and converting multi-channel fuzzy data into single-channel azimuth non-fuzzy data;
s3: and imaging the single-channel non-fuzzy data by adopting a compressed sensing method to obtain a multi-platform constellation SAR azimuth fuzzy suppression imaging result.
Wherein, the step S1 specifically comprises:
for two-dimensional SAR echo data, x (f) is determined in the range-Doppler domain a ) The autocorrelation matrix of the statistical sample of (c), let x (f) a ) The statistical sample covariance matrix of (a) is:
wherein, x (f) a ) Signal x (f) indicating the presence of ambiguity for N platforms a )＝[x 1 (f a ),x 2 (f a ),…,x N (f a )] H ，[] H Transpose of the representation vector, f a Indicating the azimuthal Doppler frequency, x (n) indicates the pair x (f) a ) Setting the Doppler fuzzy signal of N channels as x in the nth sampling under different range gates 1 (f a ),x 2 (f a ),…,x N (f a )。
Wherein, the step S2 specifically includes the following steps:
s21: constructing a multi-platform azimuth fuzzy suppression filter, wherein the specific form of the filter is as follows:
wherein, z (phi) i )＝[z 1 (φ i ),...,z N (φ i )] T Representing the corresponding spatial steering vector of the signal,
φ i indicating the angle of orientation, Δ x, of the different platforms k Representing the distance difference between the kth platform and the phase origin, and mu represents a regularization parameter;
s22: converting multi-channel fuzzy data into single-channel azimuth non-fuzzy data, and setting weighted output single channelThe channel unambiguous signal is y (f) a ) Then, there are:
y(f a )＝w H ·x(f a )；
therefore, multi-channel fuzzy data is converted into single-channel azimuth unambiguous data.
Wherein, the step S3 specifically includes the following steps:
s31: constructing a mapping relation between the backscattering coefficient of the target and single-channel azimuth unambiguous data:
y＝Φx+N；
wherein x represents the backscattering coefficient of the target; y represents single-channel azimuthal unambiguous data; phi represents a radar observation matrix; n represents system noise;
s32: optimizing the backscattering coefficient x of the target, wherein the specific calculation formula is as follows:
wherein λ is a regularization parameter;
s33: and obtaining a multi-platform constellation SAR azimuth fuzzy suppression imaging result according to the optimized backscattering coefficient x.
Compared with the prior art, the technical scheme of the invention has the beneficial effects that:
according to the multi-platform constellation SAR fusion coherent imaging method provided by the invention, a mode of weighting a plurality of platform data is adopted, azimuth ambiguity is effectively inhibited, the problem of azimuth ambiguity in the process of realizing wide swath imaging of a single platform is solved, a compressed sensing technology is adopted, single-channel azimuth unambiguous data is imaged, side lobes can be effectively inhibited, and the imaging quality is ensured.
Drawings
Fig. 1 is a flow diagram of a multi-platform constellation SAR fusion coherent imaging method.
Detailed Description
The drawings are for illustrative purposes only and are not to be construed as limiting the patent;
for the purpose of better illustrating the present embodiments, certain elements of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product;
it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.
The technical solution of the present invention is further described below with reference to the accompanying drawings and examples.
Example 1
As shown in fig. 1, a multi-platform constellation SAR fusion coherent imaging method includes the following steps:
s1: determining a noise covariance matrix between each platform according to echo data received by a plurality of platforms;
s2: constructing a multi-platform azimuth fuzzy suppression filter, and converting multi-channel fuzzy data into single-channel azimuth non-fuzzy data;
s3: and imaging the single-channel non-fuzzy data by adopting a compressed sensing method to obtain a multi-platform constellation SAR azimuth fuzzy suppression imaging result.
More specifically, the step S1 specifically includes:
for two-dimensional SAR echo data, x (f) is determined in the range-Doppler domain a ) The statistical sample autocorrelation matrix of (c), let x (f) a ) The statistical sample covariance matrix of (a) is:
wherein, x (f) a ) Signal x (f) indicating the presence of ambiguity for N platforms a )＝[x 1 (f a ),x 2 (f a ),…,x N (f a )] H ，[] H Representing the transpose of the vector, f a Indicating the azimuthal Doppler frequency, x (n) indicates the pair x (f) a ) Setting the Doppler fuzzy signal of N channels as x in the nth sampling under different range gates 1 (f a ),x 2 (f a ),…,x N (f a )。
More specifically, the step S2 specifically includes the following steps:
s21: constructing a multi-platform azimuth fuzzy suppression filter, wherein the specific form of the filter is as follows:
wherein, z (phi) i )＝[z 1 (φ i ),...,z N (φ i )] T Representing the corresponding spatial steering vector of the signal,
φ i indicating the angle of orientation, Δ x, of the different platforms k Representing the distance difference between the kth platform and the phase origin, and mu represents a regularization parameter;
s22: converting multi-channel fuzzy data into single-channel azimuth non-fuzzy data, and setting the weighted output single-channel non-fuzzy signal as y (f) a ) Then, there are:
y(f a )＝w H ·x(f a )；
therefore, multi-channel fuzzy data is converted into single-channel azimuth non-fuzzy data.
More specifically, the step S3 specifically includes the following steps:
s31: constructing a mapping relation between the backscattering coefficient of the target and single-channel azimuth unambiguous data:
y＝Φx+N；
wherein x represents the backscattering coefficient of the target; y represents single-channel azimuth unambiguous data; phi represents a radar observation matrix; n represents system noise;
s32: optimizing the backscattering coefficient x of the target, wherein the specific calculation formula is as follows:
wherein λ is a regularization parameter;
s33: and obtaining a multi-platform constellation SAR azimuth fuzzy suppression imaging result according to the optimized backscattering coefficient x.
In a specific implementation process, the multi-platform constellation SAR fusion coherent imaging method provided by the invention adopts a mode of weighting a plurality of platform data, effectively inhibits azimuth ambiguity, avoids the problem of azimuth ambiguity in the process of realizing wide swath imaging by a single platform, adopts a compressed sensing technology to image single-channel azimuth unambiguous data, and can effectively inhibit side lobes to ensure imaging quality.
It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.
Claims (2)
1. A multi-platform constellation SAR fusion coherent imaging method is characterized by comprising the following steps:
s1: determining a noise covariance matrix among the platforms according to echo data received by the platforms;
the step S1 specifically comprises the following steps:
for two-dimensional SAR echo data, x (f) is determined in the range-Doppler domain a ) The statistical sample autocorrelation matrix of (c), let x (f) a ) The statistical sample covariance matrix of (a) is:
wherein, x (f) a ) Signal x (f) indicating the presence of ambiguity for N platforms a )＝[x 1 (f a ),x 2 (f a ),…,x N (f a )] H ，[] H Representing the transpose of the vector, f a Indicating the azimuthal Doppler frequency, x (n) indicates the pair x (f) a ) Setting the Doppler fuzzy signal of N channels as x in the nth sampling under different range gates 1 (f a ),x 2 (f a ),…,x N (f a )；
S2: constructing a multi-platform azimuth fuzzy suppression filter, and converting multi-channel fuzzy data into single-channel azimuth non-fuzzy data;
the step S2 specifically includes the following steps:
s21: constructing a multi-platform azimuth fuzzy suppression filter, wherein the specific form of the filter is as follows:
wherein, z (phi) i )＝[z 1 (φ i ),...,z N (φ i )] T Representing the corresponding spatial steering vector of the signal,
φ i indicating the angle of orientation, Δ x, of the different platforms k Representing the distance difference between the kth platform and the phase origin, and mu represents a regularization parameter;
s22: converting multi-channel fuzzy data into single-channel azimuth direction non-fuzzy data, and setting the weighted output single-channel non-fuzzy signal as y (f) a ) Then, there are:
y(f a )＝w H ·x(f a )；
so as to convert the multi-channel fuzzy data into single-channel azimuth non-fuzzy data;
s3: and imaging the single-channel non-fuzzy data by adopting a compressed sensing method to obtain a multi-platform constellation SAR azimuth fuzzy suppression imaging result.
2. The multi-platform constellation SAR fusion coherent imaging method according to claim 1, wherein said step S3 specifically comprises the steps of:
s31: constructing a mapping relation between the backscattering coefficient of the target and single-channel azimuth unambiguous data:
y＝Φx+N；
wherein x represents the backscattering coefficient of the target; y represents single-channel azimuth unambiguous data; phi represents a radar observation matrix; n represents system noise;
s32: optimizing the backscattering coefficient x of the target, wherein the specific calculation formula is as follows:
wherein λ is a regularization parameter;
s33: and obtaining a multi-platform constellation SAR azimuth fuzzy suppression imaging result according to the optimized backscattering coefficient x.
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| US8493262B2 (en) * | 2011-02-11 | 2013-07-23 | Mitsubishi Electric Research Laboratories, Inc. | Synthetic aperture radar image formation system and method |
| CN103630897A (en) * | 2012-08-28 | 2014-03-12 | 中国科学院电子学研究所 | Multichannel synthetic aperture radar imaging method |
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