Phase synchronization and multi-channel equalization coordinated phase-preserving processing method and device

Abstract

The present invention provides a phase synchronization and multi-channel equalization coordinated phase-preserving processing method and device, which relates to the field of distributed azimuth multi-channel interferometric SAR satellite remote sensing data preprocessing technology, and is used to solve the technical problem that the phase synchronization data link in the prior art does not cover all data channels, resulting in the destruction of the phase synchronization compensation result during equalization processing. The method includes: first, according to the auxiliary data mark of the satellite multi-channel data, extracting the receiving channel number and the phase synchronization signal where the phase synchronization signal is located, obtaining the synchronous phase compensation amount to compensate for the echo data of each channel of the auxiliary satellite, and eliminating the phase difference between the main and auxiliary satellites; secondly, taking the first channel as a reference, performing data equalization processing on the multi-channel data, obtaining the phase error between each channel, and converting the reference channel to the phase error according to the phase synchronization data channel number, compensating it to the echo data of each channel, and eliminating the phase difference between the channels.

Description

Technical Field

[0001] The present invention relates to the technical field of distributed azimuth multi-channel interferometric SAR satellite remote sensing data preprocessing, and more specifically, to a phase synchronization and multi-channel equalization coordinated phase-preserving processing method and device. Background Art

[0002] Distributed azimuth multi-channel interferometric synthetic aperture radar (SAR) satellite is an important technical means to achieve efficient and high-precision global terrain mapping.

[0003] The distributed interferometric SAR satellite system combines satellite formations with interferometric SAR technology. It is generally composed of two satellites to form a long and stable baseline. Two SAR image data are obtained at the same time, and then interferometric processing is performed to obtain ground elevation information through interferometric phase to obtain a digital elevation model product. The two satellites use their own independent frequency sources. There is a deviation between the modulation frequency of the transmitting satellite and the demodulation frequency of the receiving satellite. The transmitting phase noise is decoupled from the receiving phase noise. There are frequency source differences and phase noise in the echo phase. The phase error caused by the phase noise varies along the azimuth direction, which will seriously affect the accuracy of elevation inversion.

[0004] The existing distributed multi-channel interferometric SAR satellite phase synchronization data link does not cover all data channels, but only exists in a specific data channel, and may change in different shooting tasks. In data processing, phase synchronization data processing and multi-channel equalization processing are performed independently. Generally, the data of each channel of the auxiliary satellite is compensated for the synchronization phase first, and then multi-channel equalization processing is performed to correct the phase error between the channels. The phase retention characteristics of the entire processing link are not involved, which will lead to the destruction of the compensation result of phase synchronization during equalization processing. Summary of the invention

[0005] In view of this, the present invention provides a phase synchronization and multi-channel equalization coordinated phase-preserving processing method and device to solve the technical problem that the phase synchronization data link in the prior art does not cover all data channels, resulting in the destruction of the phase synchronization compensation result during equalization processing.

[0006] One aspect of the present invention provides a phase synchronization and multi-channel equalization coordinated phase-preserving processing method, comprising: determining the receiving channel where the phase synchronization signal is located according to the auxiliary data corresponding to the main satellite and the auxiliary data corresponding to the auxiliary satellite respectively; extracting the phase synchronization signal in the corresponding receiving channel, and demodulating the phase synchronization signal to obtain the synchronization phase; compensating the synchronization phase to each channel signal of the auxiliary satellite to eliminate the phase difference between the main satellite and the auxiliary satellite; performing data equalization processing on the multi-channel echo data of the main satellite and the multi-channel echo data of the auxiliary satellite respectively with the first receiving channel as a reference to obtain the channel phase error between each receiving channel inside the main satellite and the auxiliary satellite; performing reference channel conversion on the channel phase error of the main satellite and the auxiliary satellite respectively according to the receiving channel where the phase synchronization signal of the main satellite and the receiving channel where the phase synchronization signal of the auxiliary satellite are located; compensating the converted channel phase error to each channel signal of the main satellite and each channel signal of the auxiliary satellite respectively to eliminate the phase difference between each channel inside the main satellite and the phase difference between each channel inside the auxiliary satellite.

[0007] According to an embodiment of the present invention, demodulating the phase synchronization signal to obtain the synchronization phase includes: respectively acquiring the frequency sources of the primary star and the auxiliary star, the frequency errors of the frequency sources that change with time, and the distance between the primary star and the auxiliary star; in response to the auxiliary star receiving the synchronization signal sent by the primary star, demodulating to obtain a first synchronization phase according to the frequency source, the frequency error and the distance; in response to the primary star receiving the synchronization signal sent by the auxiliary star, demodulating to obtain a second synchronization phase according to the frequency source, the frequency error and the distance.

[0008] According to an embodiment of the present invention, the phase synchronization signal is demodulated to obtain the synchronization phase, and the method further includes: calculating the phase difference between the primary satellite and the secondary satellite based on the first synchronization phase and the second synchronization phase; and filtering the phase difference by phase noise and local oscillator frequency deviation to obtain the filtered phase difference.

[0009] According to an embodiment of the present invention, the synchronization phase is compensated to each channel signal of the auxiliary satellite to eliminate the phase difference between the primary satellite and the auxiliary satellite, including: calculating a compensation signal based on the phase difference after filtering; and compensating each channel signal of the auxiliary satellite according to the compensation signal.

[0010] According to an embodiment of the present invention, data equalization processing is performed on multi-channel echo data of a primary satellite and multi-channel echo data of an auxiliary satellite respectively with the first receiving channel as a reference to obtain channel phase errors between respective receiving channels inside the primary satellite and the auxiliary satellite, including: extracting echo signals according to the multi-channel echo data; calculating the covariance matrix of the echo signals based on an orthogonal subspace method; and calculating the channel phase errors between respective receiving channels inside the primary satellite and the auxiliary satellite based on the covariance matrix.

[0011] According to an embodiment of the present invention, based on the covariance matrix, calculating the channel phase error between each receiving channel inside the primary satellite and the auxiliary satellite includes: performing eigendecomposition processing on the covariance matrix to obtain a signal subspace matrix and a noise subspace matrix; based on the signal subspace matrix and the noise subspace matrix, calculating the channel phase error between each receiving channel inside the primary satellite and the auxiliary satellite.

[0012] According to an embodiment of the present invention, performing reference channel conversion on the channel phase errors of the primary star and the auxiliary satellite according to the receiving channel where the primary star phase synchronization signal is located and the receiving channel where the auxiliary star phase synchronization signal is located, respectively, includes: performing reference channel conversion on the channel phase errors of the primary star and the auxiliary satellite based on the channel conversion matrix according to the receiving channel where the primary star phase synchronization signal is located and the receiving channel where the auxiliary star phase synchronization signal is located, respectively.

[0013] Another aspect of the present invention provides a phase synchronization and multi-channel equalization coordinated phase-preserving processing device, comprising: a determination module, used to determine the receiving channel where the phase synchronization signal is located according to the auxiliary data corresponding to the primary satellite and the auxiliary data corresponding to the auxiliary satellite; a demodulation module, used to extract the phase synchronization signal in the corresponding receiving channel, and demodulate the phase synchronization signal to obtain the synchronization phase; a first compensation module, used to compensate the synchronization phase to each channel signal of the auxiliary satellite, and eliminate the phase difference between the primary satellite and the auxiliary satellite; an equalization processing module, used to perform data equalization processing on the multi-channel echo data of the primary satellite and the multi-channel echo data of the auxiliary satellite, respectively, with the first receiving channel as a reference, to obtain the channel phase error between each receiving channel inside the primary satellite and the auxiliary satellite; a channel conversion module, used to perform reference channel conversion on the channel phase error of the primary satellite and the auxiliary satellite according to the receiving channel where the phase synchronization signal of the primary satellite is located and the receiving channel where the phase synchronization signal of the auxiliary satellite is located; a second compensation module, used to compensate the converted channel phase error to each channel signal of the primary satellite and each channel signal of the auxiliary satellite, and eliminate the phase difference between each channel inside the primary satellite and the phase difference between each channel inside the auxiliary satellite.

[0014] Another aspect of the present invention provides an electronic device, comprising: one or more processors; and a memory for storing one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors implement the above method.

[0015] Another aspect of the present invention provides a computer-readable storage medium storing computer-executable instructions, which are used to implement the above method when executed.

[0016] Another aspect of the present invention provides a computer program product, the computer program product comprising computer executable instructions, and the instructions are used to implement the above method when being executed.

[0017] Compared with the prior art, the phase synchronization and multi-channel equalization coordinated phase-preserving processing method and device provided by the present invention have at least the following beneficial effects:

[0018] (1) The phase synchronization and multi-channel equalization coordinated phase-preserving processing method and device provided in the embodiment of the present invention fully considers the correlation between phase synchronization and multi-channel data equalization, and proposes a technical concept of coordinated phase preservation. First, according to the auxiliary data mark of the satellite multi-channel data, the receiving channel number and the phase synchronization signal where the phase synchronization signal is located are extracted, and the synchronization data analysis preprocessing is performed to obtain the synchronization phase compensation amount, which is compensated to the echo data of each channel of the auxiliary satellite to eliminate the phase difference between the main and auxiliary satellites (the purpose of the first compensation). Secondly, the multi-channel data is subjected to data equalization processing with the first channel as a reference to obtain the phase error between each channel, and the phase error is converted to a reference channel according to the phase synchronization data channel number, and compensated to the echo data of each channel to eliminate the phase difference between the channels (the purpose of the second compensation), thereby solving the phase maintenance problem of the entire processing link.

[0019] (2) The phase synchronization and multi-channel equalization collaborative phase-preserving processing method and device provided in the embodiment of the present invention, because the existing data equalization methods mostly use the first channel as a reference to compensate the phase errors between other channels and the first channel. This operation will destroy the initial phase value eliminated therein. Therefore, the present invention fully considers the receiving channel where the phase synchronization signal is located, performs reference channel conversion, and does not perform phase compensation on the receiving channel, so that the initial phase value will not be destroyed.

[0020] (3) The phase synchronization and multi-channel equalization coordinated phase-preserving processing method and device provided in the embodiment of the present invention propose a robust and reliable processing method for the situation where the phase synchronization data does not cover all data channels. This can reduce the complexity of satellite synchronization data link design and has strong engineering practicality for the design of distributed multi-channel interferometric SAR satellites. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The above and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

[0022] Figure 1 A flowchart of a method for phase synchronization and multi-channel equalization coordinated phase-preserving processing according to an embodiment of the present invention is schematically shown;

[0023] Figure 2 A schematic diagram of a phase synchronization and multi-channel equalization coordinated phase-preserving processing method according to an embodiment of the present invention is shown;

[0024] Figure 3A schematic diagram shows a structural block diagram of a phase synchronization and multi-channel equalization coordinated phase-preserving processing device according to an embodiment of the present invention;

[0025] Figure 4 The structure block diagram of an electronic device suitable for implementing a phase synchronization and multi-channel equalization coordinated phase-preserving processing method according to an embodiment of the present invention is schematically shown. DETAILED DESCRIPTION

[0026] Below, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present invention. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of embodiments of the present invention. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of concepts of the present invention.

[0027] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0028] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0029] When using expressions such as "at least one of A, B, and C, etc.", they should generally be interpreted according to the meaning of the expression commonly understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0030] In the embodiments of the present invention, the collection, updating, analysis, processing, use, transmission, provision, disclosure, storage and other aspects of the data involved (for example, including but not limited to user personal information) are in compliance with the provisions of relevant laws and regulations, are used for legitimate purposes, and do not violate public order and good morals. In particular, necessary measures are taken for user personal information to prevent illegal access to user personal information data and maintain the security of user personal information and network security.

[0031] Distributed azimuth multi-channel interferometric synthetic aperture radar (SAR) satellite is an important technical means to achieve efficient and high-precision global terrain mapping.

[0032] The distributed interferometric SAR satellite system combines satellite formations with interferometric SAR technology. It is generally composed of two satellites to form a long and stable baseline. Two SAR image data are obtained at the same time, and then interferometric processing is performed. The ground elevation information is obtained through the interferometric phase to obtain a digital elevation model product. The two satellites use their own independent frequency sources. There is a deviation between the modulation frequency of the transmitting satellite and the demodulation frequency of the receiving satellite. The transmitting phase noise is de-correlated with the receiving phase noise. There are phase errors in the echo phase caused by the frequency source difference and phase noise along the azimuth and space variation, which will seriously affect the accuracy of elevation inversion. Existing satellites mostly use a pulse alternating transmission scheme to establish a synchronous link between the main and auxiliary satellites, transmit synchronization signals in both directions, extract the compensation phase from the synchronization signal, compensate it to the echo data, and eliminate the phase error caused by the frequency source difference.

[0033] Azimuth multi-channel is an important means for satellite SAR to achieve high resolution and wide mapping swath at the same time. Through the one-transmit-multiple-receive system combined with digital beamforming technology, the echoes of multiple receiving channels can be synthesized in azimuth into an equivalent single-transmit-single-receive signal, thereby ensuring a wide mapping swath while increasing the equivalent pulse repetition frequency to improve azimuth resolution. Under this system, factors such as azimuth non-uniform sampling of echo signals and amplitude and phase imbalance between channels will cause azimuth ambiguity in imaging and image phase shift, affecting the accuracy of elevation inversion. Existing satellites mostly use a solution based on internal calibration signals and echo signal estimation, select a reference channel, extract and estimate the phase difference between multiple channels, compensate for the phase errors of other channels, and then reconstruct to obtain an equivalent single-channel echo signal.

[0034] The existing distributed multi-channel interferometric SAR satellite phase synchronization data link does not cover all data channels, but only exists in a specific data channel, and may change in different shooting tasks. In data processing, phase synchronization data processing and multi-channel equalization processing are performed independently. Generally, the data of each channel of the auxiliary satellite is compensated for the synchronization phase first, and then multi-channel equalization processing is performed to correct the phase error between the channels. The phase retention characteristics of the entire processing link are not involved, which will lead to the destruction of the compensation result of phase synchronization during equalization processing.

[0035] It can be seen that the existing technology still has two defects:

[0036] (1) The phase-synchronized signal link in the existing distributed azimuth multi-channel interferometric SAR satellite does not completely cover all multi-channel data links. It only exists in a specific data channel and may change in different shooting tasks. Phase-synchronized data processing can only eliminate the initial phase value of the covered link.

[0037] (2) Azimuth multi-channel data may have phase errors between channels due to inconsistent system hardware and inconsistent satellite attitudes. It is necessary to perform data equalization on the multi-channel data to eliminate the phase errors between channels. However, existing data equalization methods mostly use the first channel as a reference to compensate for the phase errors between other channels and the first channel. This operation will destroy the initial phase value eliminated in the first step.

[0038] Based on this, an embodiment of the present invention provides a phase synchronization and multi-channel equalization coordinated phase-preserving processing method to solve the technical problem that the phase synchronization data link in the prior art does not cover all data channels, resulting in the destruction of the phase synchronization compensation result during equalization processing.

[0039] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0040] Figure 1 The flowchart of the phase synchronization and multi-channel equalization coordinated phase-preserving processing method according to an embodiment of the present invention is schematically shown.

[0041] like Figure 1 As shown, the phase synchronization and multi-channel equalization coordinated phase-preserving processing method of this embodiment may include operations S1 to S6.

[0042] In operation S1, a receiving channel where a phase synchronization signal is located is determined according to auxiliary data corresponding to a primary satellite and auxiliary data corresponding to an auxiliary satellite.

[0043] In operation S2, a phase synchronization signal is extracted from a corresponding receiving channel, and the phase synchronization signal is demodulated to obtain a synchronization phase.

[0044] In operation S3, the synchronization phase is compensated to each channel signal of the auxiliary satellite to eliminate the phase difference between the primary satellite and the auxiliary satellite.

[0045] In operation S4, data equalization processing is performed on the multi-channel echo data of the primary satellite and the multi-channel echo data of the auxiliary satellite respectively, with the first receiving channel as a reference, to obtain channel phase errors between the receiving channels in the primary satellite and the auxiliary satellite.

[0046] In operation S5, reference channel conversion is performed on the channel phase errors of the primary satellite and the secondary satellite according to the receiving channel where the primary satellite phase synchronization signal is located and the receiving channel where the secondary satellite phase synchronization signal is located.

[0047] In operation S6, the converted channel phase errors are respectively compensated to the channel signals of the primary satellite and the channel signals of the secondary satellite, so as to eliminate the phase differences between the channels in the primary satellite and the phase differences between the channels in the secondary satellite.

[0048] The phase synchronization and multi-channel equalization coordinated phase-preserving processing method provided in the embodiment of the present invention fully considers the correlation between phase synchronization and multi-channel data equalization, and proposes a technical concept of coordinated phase preservation. First, according to the auxiliary data mark of the satellite multi-channel data, the receiving channel number and the phase synchronization signal where the phase synchronization signal is located are extracted, and the synchronous data analysis preprocessing is performed to obtain the synchronous phase compensation amount, which is compensated to the echo data of each channel of the auxiliary satellite to eliminate the phase difference between the main and auxiliary satellites (this is the purpose of the first compensation). Secondly, with the first channel as a reference, the multi-channel data is subjected to data equalization processing to obtain the phase error between each channel, and according to the phase synchronization data channel number, the phase error is converted to a reference channel and compensated to the echo data of each channel to eliminate the phase difference between the channels (this is the purpose of the second compensation), thereby solving the phase maintenance problem of the entire processing link.

[0049] In this embodiment, operation S1 determines the receiving channel where the phase synchronization signal is located according to the auxiliary data corresponding to the primary satellite and the auxiliary data corresponding to the auxiliary satellite, for example:

[0050] The channel numbers of the phase synchronization signals are extracted from the auxiliary data of the primary and auxiliary satellites respectively, and the corresponding flag bits in the multi-channel auxiliary data are retrieved to obtain the channel numbers of the phase synchronization signals. Taking ten channels as an example, in the data obtained in a certain shooting mission, the channel number of the primary satellite phase synchronization signal is 2, and the channel number of the auxiliary satellite phase synchronization signal is 7.

[0051] According to an embodiment of the present invention, operation S2 demodulates the phase synchronization signal to obtain a synchronization phase, which may include, for example:

[0052] Respectively obtain the frequency sources of the primary star and the auxiliary star, the frequency errors of the frequency sources varying with time, and the distance between the primary star and the auxiliary star;

[0053] In response to the auxiliary satellite receiving the synchronization signal sent by the primary satellite, demodulating to obtain a first synchronization phase according to the frequency source, the frequency error and the distance;

[0054] In response to the primary satellite receiving the synchronization signal sent by the secondary satellite, the second synchronization phase is obtained by demodulation according to the frequency source, the frequency error and the distance.

[0055] Distributed interferometric SAR mostly adopts a synchronous signal pulse transmission scheme in hardware design. A special phase-synchronized link is established between the primary satellite and the auxiliary satellite. The synchronization signal is transmitted through this link. In addition to transmitting radar pulse signals to the target and receiving echo signals, the primary satellite also transmits synchronization pulses to the auxiliary satellite and receives synchronization pulses from the auxiliary satellite. In addition to receiving the echo signals scattered by the target, the auxiliary satellite also receives synchronization pulses from the primary satellite and transmits synchronization pulses to the primary satellite. The frequency of synchronous pulse transmission is lower than the frequency of transmitting radar pulse signals.

[0056] During the startup period, the two satellites are syn The synchronization pulse transmission process can be described as follows: Assume that at time t0, the primary satellite transmits a synchronization pulse to the secondary satellite. After a period of time τ 12 After the auxiliary satellite receives the synchronization pulse, the auxiliary satellite passes through the system internal delay τ sys Then the synchronization pulse is sent to the primary star, and the primary star passes through time τ 21 Then the main satellite receives the synchronization pulse sent by the auxiliary satellite. The process of the main satellite and the auxiliary satellite sending synchronization signals to each other once completes a synchronization pulse transmission.

[0057] Due to the short time τ sys The spatial paths of the internal synchronization pulse transmission are basically the same, eliminating the phase introduced by the spatial link, and obtaining a repetition frequency of f syn The synchronous pulse sampling sequence of 12 and τ 21 represents the transmission time of the synchronization pulse and the distance d between the two satellites 12 It can be calculated as follows:

[0058]

[0059] Here, c represents the speed of light.

[0060] In this embodiment, the phase of the demodulated synchronization signal of the primary and secondary satellites is first analyzed. The secondary satellite receives the synchronization signal of the primary satellite, and the phase of the signal after its own demodulation (that is, the first synchronization phase) is:

[0061]

[0062] Among them, f1 and f2 represent the frequency sources of the primary and secondary stars respectively (both f1 and f2 are set to be constant). and Respectively represent the frequency errors of the primary and auxiliary satellite frequency sources over time, d 12 Indicates the distance between the primary star and the secondary star.

[0063] Similarly, when the primary satellite receives the synchronization signal from the secondary satellite, the signal phase after its own demodulation (that is, the second synchronization phase) is:

[0064]

[0065] According to an embodiment of the present invention, operation S2 demodulates the phase synchronization signal to obtain a synchronization phase, and for example, may further include:

[0066] The phase difference between the primary star and the secondary star is calculated according to the first synchronization phase and the second synchronization phase;

[0067] The phase difference is subjected to phase noise and local oscillator frequency deviation filtering to obtain a filtered phase difference.

[0068] In this embodiment, the first synchronization phase and the second synchronization phase obtained above are subtracted to obtain the phase difference between the primary star and the secondary star:

[0069]

[0070] Where s represents the time-integrated variable.

[0071] Assuming that the phase noise and local oscillator frequency deviation change slowly during the transmission of the synchronization signal, the phase difference between the primary and secondary satellites can be further expressed as (phase difference after filtering):

[0072]

[0073] According to an embodiment of the present invention, operation S3 compensates the synchronization phase to each channel signal of the auxiliary satellite to eliminate the phase difference between the primary satellite and the auxiliary satellite, which may include, for example:

[0074] Based on the phase difference after filtering, a compensation signal is calculated;

[0075] According to the compensation signal, each channel signal of the auxiliary satellite is compensated.

[0076] In this embodiment, according to the phase difference between the primary star and the secondary star calculated in the previous step, the It is used as a synchronous compensation signal to correct all time-varying phase error terms in the radar signal phase difference.

[0077] The residual phase expression is obtained by subtracting the radar signal phase difference from the synchronous compensation phase (compensation signal):

[0078]

[0079] Among them, d 12 Indicates the baseline length between the main and auxiliary satellites. In a distributed interferometric SAR system, it is generally 300-800 meters. Even if the baseline is at the km level, The value of is also very small, so the residual phase According to the above analysis, the synchronization phase can be interpolated N times in this embodiment ( , PRF represents the pulse repetition frequency of the echo signal) to perform phase compensation on each frame of radar signal.

[0080] According to an embodiment of the present invention, operation S4 performs data equalization processing on the multi-channel echo data of the primary satellite and the multi-channel echo data of the auxiliary satellite respectively, using the first receiving channel as a reference, to obtain the channel phase error between each receiving channel in the primary satellite and the auxiliary satellite, for example, which may include:

[0081] Extracting echo signals according to multi-channel echo data;

[0082] Based on the orthogonal subspace method, the covariance matrix of the echo signal is calculated;

[0083] Based on the covariance matrix, the channel phase errors between the receiving channels in the primary and auxiliary satellites are calculated.

[0084] According to an embodiment of the present invention, based on the covariance matrix, the channel phase error between each receiving channel in the primary satellite and the auxiliary satellite is calculated, for example, which may include:

[0085] Perform eigendecomposition on the covariance matrix to obtain the signal subspace matrix and the noise subspace matrix;

[0086] Based on the signal subspace matrix and the noise subspace matrix, the channel phase errors between the receiving channels inside the primary and auxiliary satellites are calculated.

[0087] In actual systems, due to various non-ideal external conditions, each receiving sub-aperture will inevitably have systematic errors, including amplitude error, phase error, range sampling delay error and position error. Various types of errors will lead to mismatch of the ideal reconstruction filter or steering vector, reduce the performance of non-uniform signal reconstruction, and ultimately cause several pairs of false targets to appear in the azimuth direction of the imaging result, affecting product quality and the accuracy of subsequent interference processes or image interpretation.

[0088] Echo signal received by the mth sub-aperture in single-transmit multiple-receive mode , the response function after pulse compression can be expressed as:

[0089]

[0090] Among them, ρ m , m and Δτ m represent the amplitude, phase and range sampling delay errors of the mth sub-aperture respectively.

[0091] Using the vector representation method, the azimuth multi-channel SAR signal can be expressed as:

[0092]

[0093] in,

[0094]

[0095]

[0096]

[0097]

[0098]

[0099] Among them, Γ(γ) represents the amplitude and phase error matrix, diag(∙) represents a vector whose elements are on the main diagonal of the matrix, (∙) T represents the matrix transpose operation, A(f n ) represents the matrix of the space steering vector, a i (f n ) represents the spatial steering vector, S0(τ,f n ) represents the multi-channel echo signal in the range time domain and azimuth frequency domain, N(τ,f n ) represents the noise signal.

[0100] The orthogonal subspace method assumes that when the payload receives a scene echo signal, the amplitude and phase errors between channels are constant. Under the disturbance of channel error, the covariance matrix of the echo signal is:

[0101]

[0102] The idea of ​​eigendecomposition was originally used in array signal processing to determine the direction of signal arrival and estimate the amplitude and phase errors of the system. In addition, the covariance matrix The eigendecomposition of can be expressed as:

[0103]

[0104] In a high-resolution wide-band spaceborne SAR system, the eigenvalues ​​can be obtained by eigendecomposition of the sample covariance matrix and arranged in descending order, for example:

[0105]

[0106] where Σ=diag[λ1,⋯,λ m ,⋯,λ M ], the corresponding U=[u1,⋯,u m ,⋯,u M].

[0107] U s is a signal subspace matrix of M×(2I+1) dimensions, which is formed by the eigenvectors corresponding to (2I+1) relatively large eigenvalues, and U N The noise subspace matrix is ​​a M×(M-(2I+1))-dimensional matrix formed by the eigenvectors corresponding to the remaining (M-(2I+1)) relatively small eigenvalues. η )The signal subspace spanned by is orthogonal to the noise subspace, so:

[0108]

[0109] In this way, the phase error can be obtained by solving the following optimization equation:

[0110]

[0111] Among them, Q i represents the diagonal matrix formed by the space steering vector, Q i =diag{a i}, taking the middle sub-aperture as the reference channel weight vector w=[0,⋯0,1,0,⋯0] T .

[0112] Finally, the optimal solution for phase error is:

[0113]

[0114] Among them, the noise subspace spectrum , H stands for conjugate transpose.

[0115] According to an embodiment of the present invention, operation S5 performs reference channel conversion on the channel phase errors of the primary satellite and the auxiliary satellite according to the receiving channel where the primary satellite phase synchronization signal is located and the receiving channel where the auxiliary satellite phase synchronization signal is located, for example, may include:

[0116] According to the receiving channel where the phase synchronization signal of the primary satellite and the receiving channel where the phase synchronization signal of the auxiliary satellite are located, reference channel conversion is performed on the channel phase errors of the primary satellite and the auxiliary satellite based on the channel conversion matrix.

[0117] In this embodiment, according to the channel number where the synchronization signal is located, the channel phase error obtained in the previous step is converted into a reference channel, and the converted channel phase error is compensated to each data channel to complete phase synchronization and multi-channel data equalization coordinated phase preservation processing.

[0118] The phase errors between channels estimated with the first channel as the reference channel are shown below:

[0119]

[0120] Where N represents the number of channels.

[0121] Assuming that the data channel number of the synchronization signal is p, the channel phase error needs to be converted to the reference channel to obtain a new channel phase error:

[0122]

[0123]

[0124] Among them, I N represents the N×N identity matrix, and A represents the channel conversion matrix, whose size is also N×N.

[0125] The phase synchronization and multi-channel equalization collaborative phase-preserving processing method provided in the embodiment of the present invention, since the existing data equalization methods mostly use the first channel as a reference to compensate for the phase errors between other channels and the first channel, this operation will destroy the initial phase value eliminated therein. The present invention fully considers the receiving channel where the phase synchronization signal is located, performs a reference channel conversion, and does not perform phase compensation on the receiving channel, so it will not destroy the initial phase value.

[0126] Finally, operation S6 is performed to compensate the converted channel phase error (phase error amount) to each channel signal of the primary satellite and each channel signal of the auxiliary satellite, thereby eliminating the phase difference between each channel in the primary satellite and the phase difference between each channel in the auxiliary satellite, and completing the phase synchronization and multi-channel data equalization coordinated phase preservation processing.

[0127] The phase synchronization and multi-channel equalization coordinated phase-preserving processing method provided in the embodiment of the present invention proposes a robust and reliable processing method for the situation where the phase synchronization data does not cover all data channels. It can reduce the complexity of satellite synchronization data link design and has strong engineering practicality for distributed multi-channel interferometric SAR satellite design.

[0128] Figure 2 The principle diagram of the phase synchronization and multi-channel equalization coordinated phase-preserving processing method according to an embodiment of the present invention is schematically shown.

[0129] like Figure 2 As shown, the principle of the phase synchronization and multi-channel equalization coordinated phase-preserving processing method of this embodiment is as follows:

[0130] Acquire the echo data and auxiliary data of N channels of the primary satellite; and acquire the echo data and auxiliary data of N channels of the auxiliary satellite.

[0131] The channel number where the phase synchronization signal is located is extracted from the auxiliary data of the primary satellite; and the channel number where the phase synchronization signal is located is extracted from the auxiliary data of the auxiliary satellite.

[0132] The phase synchronization signal is extracted from the corresponding channel, analyzed and processed to obtain the synchronization phase, and then compensated to each channel data of the auxiliary satellite.

[0133] The orthogonal subspace method is used to equalize the multi-channel echo data of the primary satellite with the first channel as a reference to obtain the phase error between each channel; and the orthogonal subspace method is used to equalize the multi-channel echo data of the auxiliary satellite with the first channel as a reference to obtain the phase error between each channel.

[0134] According to the channel number where the synchronization signal of the main satellite is located, the channel phase error of the main satellite is converted into a reference channel, and the converted channel phase error is compensated to each data channel to complete the multi-channel data equalization processing; and according to the channel number where the synchronization signal of the auxiliary satellite is located, the channel phase error of the auxiliary satellite is converted into a reference channel, and the converted channel phase error is compensated to each data channel to complete the multi-channel data equalization processing.

[0135] Figure 3 The structure block diagram of the phase synchronization and multi-channel equalization coordinated phase-preserving processing device according to an embodiment of the present invention is schematically shown.

[0136] like Figure 3 As shown, the satellite-borne photon counting laser ranging forward scatter correction device 300 of the embodiment of the present invention includes: a determination module 310, a demodulation module 320, a first compensation module 330, an equalization processing module 340, a channel conversion module 350 and a second compensation module 360.

[0137] The determination module 310 is used to determine the receiving channel where the phase synchronization signal is located according to the auxiliary data corresponding to the primary satellite and the auxiliary data corresponding to the auxiliary satellite.

[0138] The demodulation module 320 is used to extract a phase synchronization signal from a corresponding receiving channel, and perform demodulation processing on the phase synchronization signal to obtain a synchronization phase.

[0139] The first compensation module 330 is used to compensate the synchronization phase to each channel signal of the auxiliary satellite, so as to eliminate the phase difference between the primary satellite and the auxiliary satellite.

[0140] The equalization processing module 340 is used to perform data equalization processing on the multi-channel echo data of the primary satellite and the multi-channel echo data of the auxiliary satellite respectively, using the first receiving channel as a reference, to obtain the channel phase error between each receiving channel inside the primary satellite and the auxiliary satellite.

[0141] The channel conversion module 350 is used to perform reference channel conversion on the channel phase errors of the primary satellite and the auxiliary satellite according to the receiving channel where the primary satellite phase synchronization signal is located and the receiving channel where the auxiliary satellite phase synchronization signal is located.

[0142] The second compensation module 360 ​​is used to compensate the converted channel phase errors to the channel signals of the primary satellite and the channel signals of the auxiliary satellite respectively, so as to eliminate the phase differences between the channels in the primary satellite and the phase differences between the channels in the auxiliary satellite.

[0143] According to the embodiments of the present invention, any one or more of the modules, submodules, units, and subunits, or at least part of the functions of any one of them can be implemented in one module. According to the embodiments of the present invention, any one or more of the modules, submodules, units, and subunits can be split into multiple modules for implementation. According to the embodiments of the present invention, any one or more of the modules, submodules, units, and subunits can be at least partially implemented as hardware circuits, such as field programmable gate arrays (FPGAs), programmable logic arrays (PLAs), systems on chips, systems on substrates, systems on packages, application specific integrated circuits (ASICs), or can be implemented by hardware or firmware in any other reasonable way of integrating or packaging the circuit, or by any one of the three implementation methods of software, hardware, and firmware, or by a proper combination of any of them. Alternatively, according to the embodiments of the present invention, one or more of the modules, submodules, units, and subunits can be at least partially implemented as computer program modules, and when the computer program modules are run, the corresponding functions can be executed.

[0144] For example, any multiple of the determination module 310, the demodulation module 320, the first compensation module 330, the equalization processing module 340, the channel conversion module 350, and the second compensation module 360 ​​can be combined in one module / unit / sub-unit for implementation, or any one of the modules / units / sub-units can be split into multiple modules / units / sub-units. Alternatively, at least part of the functions of one or more of these modules / units / sub-units can be combined with at least part of the functions of other modules / units / sub-units and implemented in one module / unit / sub-unit. According to an embodiment of the present invention, at least one of the determination module 310, the demodulation module 320, the first compensation module 330, the equalization processing module 340, the channel conversion module 350 and the second compensation module 360 ​​can be at least partially implemented as a hardware circuit, such as a field programmable gate array (FPGA), a programmable logic array (PLA), a system on a chip, a system on a substrate, a system on a package, an application-specific integrated circuit (ASIC), or can be implemented by hardware or firmware such as any other reasonable way of integrating or packaging the circuit, or implemented in any one of the three implementation methods of software, hardware and firmware or in any appropriate combination of any of them. Alternatively, at least one of the determination module 310, the demodulation module 320, the first compensation module 330, the equalization processing module 340, the channel conversion module 350 and the second compensation module 360 ​​can be at least partially implemented as a computer program module, and when the computer program module is run, the corresponding function can be performed.

[0145] It should be noted that the phase synchronization and multi-channel equalization collaborative phase-preserving processing device part in the embodiment of the present invention corresponds to the phase synchronization and multi-channel equalization collaborative phase-preserving processing method part in the embodiment of the present invention. The description of the phase synchronization and multi-channel equalization collaborative phase-preserving processing device part specifically refers to the phase synchronization and multi-channel equalization collaborative phase-preserving processing method part, which will not be repeated here.

[0146] Figure 4 The structure block diagram of an electronic device suitable for implementing a phase synchronization and multi-channel equalization coordinated phase-preserving processing method according to an embodiment of the present invention is schematically shown. Figure 4 The electronic device shown is only an example and should not bring any limitation to the functions and scope of use of the embodiments of the present invention.

[0147] like Figure 4As shown, the electronic device 400 according to an embodiment of the present invention includes a processor 401, which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM) 402 or a program loaded from a storage part 408 into a random access memory (RAM) 403. The processor 401 may include, for example, a general-purpose microprocessor (e.g., a CPU), an instruction set processor and / or a related chipset and / or a special-purpose microprocessor (e.g., an application-specific integrated circuit (ASIC)), etc. The processor 401 may also include an onboard memory for caching purposes. The processor 401 may include a single processing unit or multiple processing units for performing different actions of the method flow according to an embodiment of the present invention.

[0148] In the storage part 408, various programs and data required for the operation of the electronic device 400 are stored. The processor 401, the ROM 402 and the storage part 408 are connected to each other through the bus 404. The processor 401 performs various operations of the method flow according to the embodiment of the present invention by executing the program in the ROM 402 and / or the storage part 408. It should be noted that the program can also be stored in one or more memories other than the ROM 402 and the storage part 408. The processor 401 can also perform various operations of the method flow according to the embodiment of the present invention by executing the program stored in the one or more memories.

[0149] According to an embodiment of the present invention, the electronic device 400 may further include an input / output (I / O) interface 405, which is also connected to the bus 404. The electronic device 400 may further include one or more of the following components connected to the input / output (I / O) interface 405: an input portion 406 including a keyboard, a mouse, etc.; an output portion 407 including a cathode ray tube (CRT), a liquid crystal display (LCD), etc., and a speaker, etc.; a storage portion 408 including a hard disk, etc.; and a communication portion 409 including a network interface card such as a LAN card, a modem, etc. The communication portion 409 performs communication processing via a network such as the Internet. A drive 410 is also connected to the input / output (I / O) interface 405 as needed. A removable medium 411, such as a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, etc., is installed on the drive 410 as needed, so that a computer program read therefrom is installed into the storage portion 408 as needed.

[0150] According to an embodiment of the present invention, the method flow according to an embodiment of the present invention can be implemented as a computer software program. For example, an embodiment of the present invention includes a computer program product, which includes a computer program carried on a computer-readable storage medium, and the computer program includes a program code for executing the method shown in the flowchart. In such an embodiment, the computer program can be downloaded and installed from the network through the communication part 409, and / or installed from the removable medium 411. When the computer program is executed by the processor 401, the above-mentioned functions defined in the system of the embodiment of the present invention are executed. According to an embodiment of the present invention, the system, equipment, device, module, unit, etc. described above can be implemented by a computer program module.

[0151] The present invention also provides a computer-readable storage medium, which may be included in the device / apparatus / system described in the above embodiment; or may exist independently without being assembled into the device / apparatus / system. The above computer-readable storage medium carries one or more programs, and when the above one or more programs are executed, the method according to the embodiment of the present invention is implemented.

[0152] According to an embodiment of the present invention, the computer-readable storage medium may be a non-volatile computer-readable storage medium. For example, it may include but is not limited to: a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof. In the present invention, the computer-readable storage medium may be any tangible medium containing or storing a program, which may be used by or in combination with an instruction execution system, an apparatus or a device.

[0153] For example, according to an embodiment of the present invention, the computer-readable storage medium may include the ROM 402 and / or the storage portion 408 described above and / or one or more memories other than the ROM 402 and the storage portion 408 .

[0154] An embodiment of the present invention also includes a computer program product, which includes a computer program, and the computer program contains program code for executing the method provided by the embodiment of the present invention. When the computer program product runs on an electronic device, the program code is used to enable the electronic device to implement the method provided by the embodiment of the present invention.

[0155] When the computer program is executed by the processor 401, the above functions defined in the system / device of the embodiment of the present invention are executed. According to the embodiment of the present invention, the system, device, module, unit, etc. described above can be implemented by a computer program module.

[0156] In one embodiment, the computer program may rely on tangible storage media such as optical storage devices, magnetic storage devices, etc. In another embodiment, the computer program may also be transmitted and distributed in the form of signals on a network medium, and downloaded and installed through the communication part 409, and / or installed from the removable medium 411. The program code contained in the computer program may be transmitted using any appropriate network medium, including but not limited to: wireless, wired, etc., or any suitable combination of the above.

[0157] According to an embodiment of the present invention, the program code for executing the computer program provided by the embodiment of the present invention can be written in any combination of one or more programming languages. Specifically, these computing programs can be implemented using high-level process and / or object-oriented programming languages, and / or assembly / machine languages. Programming languages ​​include, but are not limited to, Java, C++, python, "C" language or similar programming languages. The program code can be executed entirely on the user computing device, partially on the user device, partially on the remote computing device, or entirely on the remote computing device or server. In the case of a remote computing device, the remote computing device can be connected to the user computing device through any type of network, including a local area network (LAN) or a wide area network (WAN), or can be connected to an external computing device (e.g., using an Internet service provider to connect through the Internet).

[0158] The flowcharts and block diagrams in the accompanying drawings illustrate the possible architecture, functions and operations of the systems, methods and computer program products according to various embodiments of the present invention. In this regard, each box in the flowchart or block diagram may represent a module, a program segment, or a part of a code, and the above-mentioned module, program segment, or a part of the code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box may also occur in an order different from the order marked in the accompanying drawings. For example, two boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram or flowchart, and the combination of boxes in the block diagram or flowchart, can be implemented with a dedicated hardware-based system that performs the specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions. It can be understood by those skilled in the art that the features recorded in the various embodiments of the present invention can be combined and / or combined in various ways, even if such a combination or combination is not explicitly recorded in the present invention. In particular, without departing from the spirit and teachings of the present invention, the features recorded in the various embodiments of the present invention can be combined and / or combined in various ways. All these combinations and / or combinations fall within the scope of the present invention.

[0159] The embodiments of the present invention are described above. However, these embodiments are only for the purpose of illustration, and are not intended to limit the scope of the present invention. Although each embodiment is described above, it does not mean that the measures in each embodiment cannot be used in combination advantageously. Without departing from the scope of the present invention, those skilled in the art may make various substitutions and modifications, which should all fall within the scope of the present invention.

Claims

1. A phase synchronization and multi-channel equalization coordinated phase-preserving processing method, characterized in that: The method comprises: Determine the receiving channel where the phase synchronization signal is located according to the auxiliary data corresponding to the primary satellite and the auxiliary data corresponding to the auxiliary satellite respectively; Extracting the phase synchronization signal in the corresponding receiving channel, and demodulating the phase synchronization signal to obtain a synchronization phase; Compensating the synchronization phase into each channel signal of the auxiliary satellite to eliminate the phase difference between the primary satellite and the auxiliary satellite; Performing data equalization processing on the multi-channel echo data of the primary satellite and the multi-channel echo data of the auxiliary satellite respectively, with the first receiving channel as a reference, to obtain channel phase errors between the receiving channels in the primary satellite and the auxiliary satellite; According to the receiving channel where the phase synchronization signal of the primary satellite is located and the receiving channel where the phase synchronization signal of the secondary satellite is located, reference channel conversion is performed on the channel phase errors of the primary satellite and the secondary satellite respectively; The converted channel phase errors are compensated to the channel signals of the primary satellite and the channel signals of the auxiliary satellite respectively, so as to eliminate the phase differences between the channels in the primary satellite and the phase differences between the channels in the auxiliary satellite.

2. The method according to claim 1, characterized in that The demodulating the phase synchronization signal to obtain the synchronization phase comprises: Respectively obtaining frequency sources of the primary star and the secondary star, frequency errors of the frequency sources varying with time, and the distance between the primary star and the secondary star; In response to the auxiliary satellite receiving the synchronization signal sent by the primary satellite, demodulating to obtain a first synchronization phase according to the frequency source, the frequency error and the distance; In response to the primary satellite receiving the synchronization signal sent by the secondary satellite, a second synchronization phase is obtained by demodulation according to the frequency source, the frequency error and the distance.

3. The method according to claim 2, characterized in that The demodulating the phase synchronization signal to obtain the synchronization phase also includes: Calculating a phase difference between the primary satellite and the secondary satellite according to the first synchronization phase and the second synchronization phase; The phase difference is subjected to phase noise and local oscillator frequency deviation filtering to obtain a filtered phase difference.

4. The method according to claim 3, characterized in that: The step of compensating the synchronization phase into each channel signal of the auxiliary satellite to eliminate the phase difference between the primary satellite and the auxiliary satellite comprises: Based on the phase difference after filtering, a compensation signal is calculated; Each channel signal of the auxiliary satellite is compensated according to the compensation signal.

5. The method according to claim 1, characterized in that The performing data equalization processing on the multi-channel echo data of the primary satellite and the multi-channel echo data of the auxiliary satellite respectively with the first receiving channel as a reference to obtain the channel phase error between each receiving channel in the primary satellite and the auxiliary satellite comprises: Extracting echo signals according to the multi-channel echo data; Based on the orthogonal subspace method, the covariance matrix of the echo signal is calculated; Based on the covariance matrix, the channel phase errors between the receiving channels in the primary satellite and the auxiliary satellite are calculated.

6. The method according to claim 5, characterized in that The calculating, based on the covariance matrix, the channel phase error between each receiving channel in the primary satellite and the auxiliary satellite comprises: Performing eigendecomposition processing on the covariance matrix to obtain a signal subspace matrix and a noise subspace matrix; Based on the signal subspace matrix and the noise subspace matrix, the channel phase errors between the receiving channels inside the primary satellite and the auxiliary satellite are calculated.

7. The method according to claim 1, characterized in that The performing reference channel conversion on the channel phase errors of the primary satellite and the auxiliary satellite according to the receiving channel where the primary satellite phase synchronization signal is located and the receiving channel where the auxiliary satellite phase synchronization signal is located respectively includes: According to the receiving channel where the phase synchronization signal of the primary satellite is located and the receiving channel where the phase synchronization signal of the secondary satellite is located, reference channel conversion is performed on the channel phase errors of the primary satellite and the secondary satellite based on the channel conversion matrix.

8. A phase synchronization and multi-channel equalization coordinated phase-preserving processing device, characterized in that: The device comprises: A determination module, used to determine the receiving channel where the phase synchronization signal is located according to the auxiliary data corresponding to the primary satellite and the auxiliary data corresponding to the auxiliary satellite respectively; A demodulation module, used to extract the phase synchronization signal from the corresponding receiving channel, and demodulate the phase synchronization signal to obtain a synchronization phase; A first compensation module, used for compensating the synchronization phase into each channel signal of the auxiliary satellite to eliminate the phase difference between the primary satellite and the auxiliary satellite; an equalization processing module, used to perform data equalization processing on the multi-channel echo data of the primary satellite and the multi-channel echo data of the auxiliary satellite respectively, with the first receiving channel as a reference, to obtain channel phase errors between the receiving channels inside the primary satellite and the auxiliary satellite; A channel conversion module, used for performing reference channel conversion on the channel phase errors of the primary satellite and the auxiliary satellite according to the receiving channel where the primary satellite phase synchronization signal is located and the receiving channel where the auxiliary satellite phase synchronization signal is located; The second compensation module is used to compensate the converted channel phase errors to the channel signals of the primary satellite and the channel signals of the auxiliary satellite respectively, so as to eliminate the phase differences between the channels in the primary satellite and the phase differences between the channels in the auxiliary satellite.

9. An electronic device, characterized in that: include: one or more processors; A storage device for storing one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors execute the method according to any one of claims 1 to 7.

10. A computer-readable storage medium having executable instructions stored thereon, characterized in that: When the instruction is executed by a processor, the processor executes the method according to any one of claims 1 to 7.

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