CN114994624A

CN114994624A - Satellite-borne multi-base SAR system channel performance index measuring method

Info

Publication number: CN114994624A
Application number: CN202210935147.4A
Authority: CN
Inventors: 岳海霞; 陈亚锋; 冯晓晓; 刘开雨; 吕游; 王坤昊; 吴侠义
Original assignee: Aerospace Information Research Institute of CAS
Current assignee: Aerospace Information Research Institute of CAS
Priority date: 2022-08-05
Filing date: 2022-08-05
Publication date: 2022-09-02
Anticipated expiration: 2042-08-05
Also published as: CN114994624B

Abstract

The invention provides a satellite-borne multi-base SAR system channel performance index measuring method, which comprises 4 processes of SAR emission signal recording, generation of echo signals sent by the SAR emission signal recording, recording of echo signals sent by the SAR emission signal recording and data analysis and processing. The SAR emission signal recording process is used for recording the emission signal ST of each independent SAR in the multi-base SAR system _i (ii) a The generation process of the echo signal is to change the recorded digital transmitting signal into an analog signal to be transmitted out so as to form the echo signal transmitted by the transmitter; the recording process of the received wave signal sent by the receiving terminal completes the recording and storage of the received wave signal sent by the receiving terminal; the data analysis process is directed to its own echo signal for analysis process record storage. The invention can conveniently and flexibly select the signal in the test, and simultaneously solves the measurement limitation of darkroom space and production period to the multi-base SAR system; the limit of time and space is broken through, the measurement efficiency is improved, and the application is wider.

Description

Satellite-borne multi-base SAR system channel performance index measuring method

Technical Field

The invention belongs to the field of microwave remote sensing, and particularly relates to a method for measuring performance indexes of a satellite-borne multi-base SAR system channel.

Background

According to application requirements, the multi-base SAR system receives and transmits the information in one transmission mode so as to obtain multi-angle information of the ground target, achieve multi-angle fusion of the target, and meanwhile can obtain the elevation, the motion characteristics and the like of the ground target. The multi-base SAR system is developed, the domestic start is just started, and a method for borrowing the channel performance index test among related multi-base SAR systems does not exist.

The schematic diagram of the satellite-borne multi-base SAR system is shown in figure 1. The multi-base SAR system comprises a plurality of SAR systems. Each SAR system is provided with an independent transmitting link and an independent receiving link, the transmitting link is composed of a transmitting channel and an antenna array surface, the receiving link is composed of a receiving channel and an antenna array surface, and the antenna array surface is used as a part of the transmitting link and the receiving link to realize linear frequency modulation signal space transmission and echo signal space receiving. When the multi-base SAR system works, a plurality of SAR systems must ensure time synchronization, wherein one SAR system transmits a chirp signal ST, and other SAR systems simultaneously receive an echo signal SR. Each SAR can independently transmit a chirp signal and receive an echo signal, and can also realize the reception of only the echo signal. In the operation of the multi-base SAR system, a satellite which simultaneously transmits and receives signals of the SAR system is called a primary satellite, and a satellite which only receives signals of other SAR systems is called a secondary satellite. If SAR1 is the main satellite in FIG. 1, the transmission process of the transmitting and receiving signals is shown by a solid line, SAR1 transmits a chirp signal ST ₁ SAR1 receives the echo signal as SR ₁₁ SAR2 receives the echo signal as SR ₂₁ The SARn received echo signal is SR _n1 . If the SARn is the main satellite, the transmission process of the transmitting and receiving signals is shown by a dotted line, and the SARn transmits a linear frequency modulation signal ST _n The SARn received echo signal is SR _nn SAR1 receives the echo signal as SR _1n SAR2 receives the echo signal as SR _2n 。

Based on the above analysis, it is possible to,different error data can be introduced due to different paths of signals transmitted and received in the transmitting and receiving processes of the multi-base SAR system. For a single SAR system, the phase error Δ Φ 1 introduced by the transmit chain and the phase error Δ Φ 2 introduced by the receive chain, which are compensated into the frequency modulated signal, are extracted during development. If the ideal fm signal is: ae ^jφ The compensated fm signal is: ae ^{j(φ-Δφ1-Δφ2)} The frequency-modulated signal passing through a transmission link (K) ₁ Ae ^jΔφ1 ) And a receiving link (K) ₂ Ae ^jΔφ2 ) Then, the system receives the echo signals as follows: k ₁ K ₂ Ae ^jφ In which K is ₁ And K ₂ Amplitude weighting coefficients for the transmit chain and the receive chain, respectively. In the multi-base SAR system, the case where SAR1 is the primary satellite and the others are the secondary satellites, and the case where the signals are received by each SAR is shown in fig. 2. SAR1 transmits frequency-modulated signal Ae ^{j(φ-Δφ11-Δφ12)} Receiving echo signals through a self transmitting link and a self receiving link is as follows: k is ₁₁ K ₁₂ Ae ^j(φ) (ii) a Through the transmitting link of SAR1 and the receiving link of SAR2, SAR2 receives the echo signals as: k ₁₁ K ₂₂ Ae ^{j(φ-Δφ12+Δφ22)} (ii) a Through a transmitting link of the SAR1 and a receiving link of the SARn, the receiving echo signal of the SARn is: k ₁₁ K _n2 Ae ^{j(φ-Δφ12+Δφn2)} . The multi-base SAR system transmits signals through different receiving links, and different errors can be introduced into the amplitude and the phase of echo signals.

Accordingly, in the development of a single SAR system, the reception of the echo signal K is taken into account ₁ K ₂ Ae ^jφ The system phase error has been compensated, as long as the amplitude weighting K of the transmitting chain is strengthened ₁ And receive chain amplitude weighting K ₂ The control of the caused amplitude error, the self-sending and the self-receiving can ensure that the performance of a receiving and transmitting channel meets the imaging requirement, and the performance of the receiving and transmitting channel mainly refers to a signal broadening coefficient, a Peak Side Lobe Ratio (PSLR) and an integral side lobe ratio (SSLR). In the development of a multi-base SAR system, each independent SAR completes the development and can work as a primary satellite or a secondary satellite. When the SAR system works as a main satellite, the SAR system sends the data to the main satelliteThe channel phase error is compensated and the amplitude error is controlled within a certain range, so that the channel performance index requirement can be met. When the SAR works as a satellite, the SAR receives a transmitting linear frequency modulation signal (transmitted by the SAR) of the satellite, and different phase errors and amplitude errors are introduced through a receiving link (self-receiving) of the SAR, so that the performance index of a channel is influenced. Taking the SAR1 dominant star situation, the SARn receives the echo signal K ₁₁ K _n2 Ae ^{j(φ-Δφ12+Δφn2)} The signal introduces a new phase error (Δ φ = - Δ φ 12+ Δ φ n 2), amplitude weighting coefficient (K) ₁₁ K _n2 ) Certain amplitude errors can be caused, the performance index of a channel can be influenced inevitably, and the imaging quality of the multi-base SAR system is influenced. This requires a prior estimation of the performance indicators that the SAR sends and receives from the ground.

Considering that the measurement of the SAR system involves high power, both the system transmission and reception must be performed in a dark room, and multibasic SAR is no exception. The construction cost of the darkroom is high, the cost is higher when the darkroom is large in scale, and a darkroom with the size of 20m multiplied by 30m is calculated to be a medium-large darkroom. The antenna array face size is basically around 10m for the low-orbit SAR system. A medium sized darkroom can hold up to 2 SAR systems. Meanwhile, the SAR production period and the unit production capacity are considered, multiple bases of SAR cannot be produced at the same time, and the test is completed at the same time.

Disclosure of Invention

The invention mainly aims to provide a method for measuring performance indexes of channels of a satellite-borne multi-base SAR system, which has the characteristics of convenience, flexibility, universality and the like, can be applied to the multi-base SAR systems such as a double-base SAR system and a triple-base SAR system, and solves the problem of measuring the performance indexes of self-receiving channels between the multi-base SAR systems; the transmitting signal can be recorded and stored, the transmitting signal can be conveniently and flexibly selected in the test, and the measurement limit of a darkroom space and a production period on a multi-base SAR system is solved; the method breaks through the limitation of time and space, improves the measurement efficiency and has wider application.

In order to achieve the purpose, the invention adopts the technical scheme that:

a satellite-borne multi-base SAR system channel performance index measuring method comprises 4 processes of SAR emission signal recording, generation of echo signals, recording of echo signals and data analysis and processing;

the SAR emission signal recording process is used for recording the emission signal ST of each independent SAR in the multi-base SAR system _i At this time, a transmission signal ST _i For a digital transmitting signal, the value range of i is 1 to n, and n is the base number of the multi-base SAR system;

the echo signal generating process is used for converting the recorded digital transmitting signal into an analog signal and transmitting the analog signal to form an echo signal transmitted by the echo signal generating process; the generation process relates to the selection of digital transmission signals, DA conversion is carried out to obtain analog signals, the analog signals are delayed for a certain time through an optical delay line to form echo signals, and the echo signals are transmitted by a horn antenna; the horn antenna is placed in front of the SAR antenna array surface so that the echo signal is received by the SAR;

the recording process of the self-receiving echo signal requires that the SAR works in a receiving-only state, the echo signal is received by the antenna array surface, becomes a digital echo after passing through a receiving channel, is stored in the recorder after being recorded, and completes the recording and storage of the self-receiving echo signal;

the data analysis processing process is used for analyzing and processing the signals sent by the recorded and stored self echo signals; at this time, the self-receiving echo signal is a digital signal expressed as K _i1 K _j2 Ae ^{j(φ-Δφi2+Δφj2)} (ii) a Phi is the phase of the self-transmitting and self-receiving channel, i ranges from 1 to n, j ranges from 1 to n and does not include i, and the self-transmitting and self-receiving wave signal of the self-receiving wave signal comprises the transmitting amplitude error K of the satellite _i1 And phase error delta phi i2, self-collected amplitude error K _j2 And phase error Δ φ j 2; and obtaining the performance index of a self-receiving channel of the satellite-borne multi-base SAR system through signal analysis, and determining whether to adjust the error introduced by the satellite-borne multi-base SAR system or not through evaluation.

Further, selecting SARi as a main star, wherein the value range of i is 1 to n, and n is a positive integer; measuring the performance of a self-receiving channel of the SARj system, wherein the SARj is an auxiliary satellite, the value range of j is from 1 to n, and j is not equal to i; the method comprises the steps that a main satellite SAR transmits signals and receives echo signals at the same time; the auxiliary satellite SAR does not transmit signals and receives echo signals simultaneously with the main satellite SAR; the SAR emission signal recording process specifically comprises the following steps:

the SAR is placed in a darkroom, and emission signals of the SAR1 to the SARn are recorded respectively;

the SAR is placed in different darkrooms at different times, and the emission signal recording is not limited by time and space.

Further, the generation process of the echo signal sent by the echo generator comprises the following steps:

the test equipment group selects the transmission signal of SARi as its signaling STi, which is subjected to DA conversion, optical delay, and 1: after n power dividers, the signal is transmitted by a horn antenna to form a return wave signal transmitted by the horn antenna.

Further, the recording process of the self-receiving echo signal comprises the following steps:

the SARj antenna array receives the echo signal sent by the SARj antenna array, and the testing equipment group records and stores the digital echo signal sent by the SARj antenna array.

Further, the data analysis processing process comprises the following steps:

after analysis processing, SARj obtains the performance index of the self-receiving channel;

and evaluating the performance index of the self-receiving channel to determine whether the amplitude and phase errors of the channel are adjusted, and taking the final data as the basis of on-orbit imaging processing.

Has the advantages that: the self-echo signal is obtained by utilizing the method for measuring the performance index of the satellite-borne multi-base SAR system channel. Through data analysis, a phase error and an amplitude error introduced by a self-transmitting and self-receiving channel relative to the self-transmitting and self-receiving channel can be extracted, and the influence on the channel performance can be estimated in advance; analyzing and obtaining performance indexes of a self-transmitting and self-receiving channel of the SAR, comparing the performance indexes with the self-transmitting and self-receiving performance indexes, evaluating the influence condition on the imaging quality of the multi-base SAR system, and timely solving the problem on the factors seriously influencing the imaging performance on the ground; the self-recovery wave signal is recorded and stored, and can be used for residual error compensation in-orbit imaging, so that the in-orbit imaging quality of the multi-base SAR is improved.

Drawings

FIG. 1 is a schematic diagram of a satellite-borne multi-base SAR system in the prior art;

fig. 2 is a schematic diagram of a transmitting-receiving channel of a satellite-borne multi-base SAR system in the prior art;

FIG. 3 is a schematic diagram of a channel performance index measurement method of a satellite-borne multi-base SAR system according to the present invention;

FIG. 4 is a schematic diagram of a channel performance index measurement method of an optimized satellite-borne multi-base SAR system;

FIG. 5 is a schematic diagram of an SAR system integration test site of the present invention;

FIG. 6 is a schematic diagram of a bistatic SAR system integration test site of the present invention;

FIG. 7a and FIG. 7b are pulse pressure results of the bistatic SAR system of the present invention with 150MHz bandwidth; wherein, fig. 7a is a pulse pressure result received by transmitting SAR1 by SAR2 with a bandwidth of 150MHz, and fig. 7b is a pulse pressure result received by transmitting SAR2 by SAR1 with a bandwidth of 150 MHz;

FIG. 8a and FIG. 8b are pulse pressure results of 80MHz bandwidth of bistatic SAR system of the present invention; wherein, fig. 8a is a pulse pressure result received by transmitting SAR1 by SAR2 with a bandwidth of 80MHz, and fig. 8b is a pulse pressure result received by transmitting SAR2 by SAR1 with a bandwidth of 80 MHz;

FIG. 9a and FIG. 9b are pulse pressure results of 60MHz bandwidth for bistatic SAR system of the present invention; wherein, fig. 9a is a pulse pressure result received by transmitting SAR1 by SAR2 with a bandwidth of 60MHz, and fig. 9b is a pulse pressure result received by transmitting SAR2 by SAR1 with a bandwidth of 60 MHz.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the invention. In addition, the technical features involved in the respective embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

The invention discloses a method for measuring performance indexes of channels of a satellite-borne multi-base SAR system, which is used for solving the problem of measuring the performance indexes of self-receiving channels of the multi-base SAR system. As shown in FIG. 3, the multi-basis SAR records the respective transmitted signal ST in each independent SAR development _i (the value range of i is 1 to n, n is the cardinal number of the multi-base SAR system), and SAR which is selected as the main satelliteThe transmission signal is converted into an analog signal through DA conversion as its signal ST, and subjected to optical delay, 1: the n power dividers (1 path of input signals is changed into n paths of output signals) and the horn antenna are transmitted to the space, can enter n SAR system internal receiving links, record echo signals, and obtain the performance indexes of the channels transmitted and received by the SAR system through analysis. The method of the invention can record and store the transmitting signal of each SAR; the stored signal can be used as a signal for any selection in the test; n-1 echo signals sent and received by the SAR self-transmission device can be formed, and data analysis index extraction related to the channel of each SAR in the multi-base SAR system is completed.

In a multi-base SAR system, the method of the present invention can be optimized as shown in fig. 4 for the case where all the SAR cannot be produced simultaneously or cannot be put into the dark room for measurement simultaneously. Fig. 4 is a graph reduced by 1: the n power dividers can perform multi-base SAR measurement on one SAR system; the method is not limited by a darkroom test space, and the channel measurement of one SAR system in a multi-base SAR system is completed in each test, which relates to the following steps: the transmission signal record is stored, and the transmission signal record is sent to a self-receiving performance test, so that a plurality of SAR in the multi-base SAR system can be synchronously carried out in one or more darkrooms. In a multi-base SAR system, by using the measuring method of the invention, after the production period of an individual SAR is delayed, the test progress of other SAR is not seriously influenced, the transmitting signal of the delayed SAR is extracted, and other SAR can complete the performance index measurement of the self-receiving channel related to the delayed SAR.

The invention discloses a satellite-borne multi-base SAR system channel performance index measuring method, which relates to 4 processes of SAR emission signal recording, generation of echo signals transmitted by the SAR emission signal recording, recording of the echo signals transmitted by the SAR emission signal recording and data analysis and processing. Wherein:

1. and in the SAR emission signal recording process, the emission signal of each independent SAR in the multi-base SAR system is recorded, and the signal is a digital emission signal at the moment and is convenient to store. The emission signals are: ST (ST) _i The value range of i is 1 to n, and n is the cardinal number of the multi-base SAR system.

2. The generation process of the echo signal is to change the recorded digital transmitting signal into an analog signal to be transmitted, so as to form the echo signal to be transmitted. The generation process relates to the selection of digital transmission signals, DA conversion is carried out to obtain analog signals, the analog signals are delayed for a certain time through an optical delay line to form echo signals, and the echo signals are transmitted through a horn antenna. The horn antenna is placed in front of the SAR antenna array so that the echo signal can be received by the SAR.

3. The recording process of the self-receiving echo signal requires that the SAR works in a receiving-only state, the echo signal is received by the antenna array surface, is changed into a digital echo after passing through a receiving channel, and is stored in the recorder after being recorded, so that the recording and storage of the self-receiving echo signal are completed.

4. The data analysis process stores for the record that it is sending back a wave signal. When it sends the self-receiving echo signal as digital signal, it can be expressed as SR _ij Wherein, i ranges from 1 to n, j ranges from 1 to n, and j is not equal to i. The echo signals comprise the transmitting amplitude error and phase error of other stars, and the self-receiving amplitude error and phase error. Through signal analysis, the performance index of the self-receiving channel can be obtained, and whether the error introduced by the system needs to be adjusted or not is determined through evaluation.

To complete the measurement of a multi-base SAR system requires covering (n-1). times.n performance measurements of its transmit-receive channels.

Specifically, in the execution process of the satellite-borne multi-base SAR system channel performance index measurement method, due to the limitation of a site and a base number n, whether a power divider is used or not is selected according to needs, and the method is specifically implemented as follows:

(1) respectively recording the transmitting signals of the SAR1 to the SARn; wherein n is a positive integer;

(2) selecting SARi as a main star, wherein i ranges from 1 to n;

(3) selecting SARj as an auxiliary satellite, measuring the performance index of a self-receiving channel of the SARj, wherein the value range of j is 1 to n, and j is not equal to i;

(4) selecting a transmitting signal of SARi as a transmitting signal ST, and transmitting through a horn antenna after DA conversion, optical delay and a power divider to form a transmitting echo signal;

(5) the SARj antenna array receives the echo signal sent by the SARj antenna array, and after the echo signal passes through an SARj receiving channel, the testing equipment records and stores the echo signal to obtain digital echo signals sent by the SARj antenna array;

(6) after analysis processing, SARj obtains the performance index of the self-receiving channel;

(7) and evaluating the performance index of the self-receiving channel to determine whether the amplitude and phase errors of the channel are adjusted, wherein the final data can be used as the basis for on-orbit imaging processing.

The measurement method of the performance index of the multi-base SAR system plays a great role in the development of the bistatic SAR, and the value embodied by the method is higher as the base number n is larger. The present invention is described in detail below with specific examples.

In the development of a bistatic SAR, the development period of two SAR system products is different by 2 months, the size of an antenna array surface is 9.8m long, and two SAR systems can be put down in a dark room with the size of 20m multiplied by 30 m. The SAR1 system product development is completed to enter the darkroom and is placed on the left side of the darkroom, as shown in figure 5. The content related to the SAR1 system integration test is not explained here. After the SAR1 system integration test is completed, a test equipment group and a horn antenna 1 are set up, the multi-base SAR system channel performance index measurement method is verified, the method is confirmed to be effective, and full preparation is made for the subsequent double-base SAR system channel performance index measurement. At this point, there is no signaling from it, and the system uses the autonomous signal instead of its signaling for method validation. The test equipment group mainly completes the record storage of the transmitted signal, the DA conversion and the delay of the digital signal, and changes the transmitted signal into an analog echo signal transmitted by the test equipment group. Echo signals sent by the device are transmitted by a horn antenna 1, SAR1 antenna array surfaces are received, the signals are changed into digital echo signals sent by the device through a receiving channel, and channel performance indexes after analysis and processing are shown in table 1. Under the condition of system self-closed loop, the performance under the full-array transceiving calibration represents the performance index of a transceiving channel under the self-transceiving of the SAR system. Under the condition of 3 bandwidths (150 MHz bandwidth, 80MHz bandwidth and 60 MHz) of the SAR1 system, the self-closed loop result is basically consistent with the test result under multi-base wireless, and the method is fully proved to be capable of carrying out multi-base SAR channel performance index test.

After the SAR2 system product is developed, the product enters a darkroom, and the arrangement position inside the darkroom is shown in figure 6. The 20m 30m darkroom can just place 2 sets of SAR equipment of the lower double-base SAR system, and can simultaneously complete the channel performance test of the 2 sets of SAR equipment. At this time, the bistatic SAR system channel measurement adopts the process illustrated in fig. 3, and the specific operation steps are as follows:

1) recording the emission signals of SAR1 and SAR2 respectively;

2) selecting SAR1 as a main satellite and SAR2 as an auxiliary satellite;

3) the system working bandwidth is 150 MHz;

4) the test equipment group selects the transmitting signal of the main satellite as a transmitting signal, and generates an echo signal which is transmitted by the main satellite 1: 2, the power divider outputs to two horn antennas, and the two horn antennas are over against the two antenna array surfaces and can be used as analog echo signals of the two horn antennas;

5) the SAR1 and the SAR2 receive echo signals simultaneously, and digital echo signals are obtained through recording and storing;

6) selecting a system bandwidth of 80MHz, and repeating the step 4) and the step 5);

7) selecting a system bandwidth of 60MHz, and repeating the step 4) and the step 5);

8) after analysis processing, SAR1 obtains the performance index of the self-transmitting and self-receiving channel, and SAR2 obtains the performance index of the self-transmitting and self-receiving channel;

9) selecting SAR2 as a main satellite and SAR1 as an auxiliary satellite;

10) repeating the step 3) to the step 7), after the analysis processing, obtaining the performance index of the self-transmitting and self-receiving channel by the SAR2, and obtaining the performance index of the self-transmitting and self-receiving channel by the SAR 1;

11) the pulse pressure results of the bistatic SAR system with the bandwidth of 150MHz are shown in a figure 7a and a figure 7b, the pulse pressure results of the bandwidth of 80MHz are shown in a figure 8a and a figure 8b, the pulse pressure results of the bandwidth of 60MHz are shown in a figure 9a and a figure 9b, and the test results of the extracted channel performance indexes are shown in a table 2. The results show that it has slightly worse performance on the transmit-receive path than on the transmit-receive path, but also within the specification requirements. Can be used as the basis of bistatic SAR on-orbit imaging processing.

The method is suitable for measuring the channel performance indexes of the satellite-borne multi-base SAR system, is not limited to signal broadening coefficient, PLSR and ILSR index measurement, and can also be used for measuring channel related indexes such as channel stability, channel error extraction and the like.

TABLE 1 verification result of channel performance index measurement method of satellite-borne multi-base SAR system

TABLE 2 bistatic SAR channel Performance index test results

It will be understood by those skilled in the art that the foregoing is only an exemplary embodiment of the present invention, and is not intended to limit the invention to the particular forms disclosed, since various modifications, substitutions and improvements within the spirit and scope of the invention are possible and within the scope of the appended claims.

Claims

1. A method for measuring performance indexes of channels of a satellite-borne multi-base SAR system is characterized by comprising the following steps: the method comprises 4 processes of SAR emission signal recording, echo signal generation, echo signal recording and data analysis and processing;

the recording process of the self-receiving echo signal requires that the SAR works in a receiving-only state, the echo signal is received by the antenna array surface, is changed into a digital echo after passing through a receiving channel, and is stored in the recorder after being recorded, so that the recording and storage of the self-receiving echo signal are completed;

the data analysis processing procedure is used for analysis processingRecording the stored signal sent by the echo; at this time, the self-receiving echo signal is a digital signal expressed as K _i1 K _j2 Ae ^{j(φ-Δφi2+Δφj2)} (ii) a Phi is the phase of the self-transmitting and self-receiving channel, i ranges from 1 to n, j ranges from 1 to n and does not include i, and the self-transmitting and self-receiving wave signal of the self-receiving wave signal comprises the transmitting amplitude error K of the satellite _i1 And phase error delta phi i2, self-collected amplitude error K _j2 And phase error Δ φ j 2; and obtaining the performance index of a self-receiving channel of the satellite-borne multi-base SAR system through signal analysis, and determining whether to adjust the error introduced by the satellite-borne multi-base SAR system or not through evaluation.

2. The method for measuring the channel performance index of the satellite-borne multi-base SAR system according to claim 1, characterized in that: selecting SARi as a main star, wherein the value range of i is 1 to n, and n is a positive integer; measuring the performance of a self-receiving channel of the SARj system, wherein the SARj is an auxiliary satellite, the value range of j is 1 to n, and j is not equal to i; the method comprises the steps that a main satellite SAR transmits signals and receives echo signals at the same time; the auxiliary satellite SAR does not transmit signals and receives echo signals simultaneously with the main satellite SAR; the SAR emission signal recording process specifically comprises the following steps:

3. The method for measuring the channel performance index of the satellite-borne multi-base SAR system according to claim 2 is characterized in that: the generation process of the echo signal sent by the echo signal generator comprises the following steps:

4. The method for measuring the channel performance index of the satellite-borne multi-base SAR system according to claim 3, characterized in that: the recording process of the self-receiving echo signal comprises the following steps:

5. The method for measuring the channel performance index of the satellite-borne multi-base SAR system according to claim 4, characterized in that: the data analysis processing process comprises the following steps:

and evaluating the performance indexes of the self-receiving channels to determine whether to adjust the amplitude and phase errors of the channels, and taking the final data as the basis of on-orbit imaging processing.