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CN-122017843-A - Synthetic aperture radar echo signal processing method and device

CN122017843ACN 122017843 ACN122017843 ACN 122017843ACN-122017843-A

Abstract

The invention provides a synthetic aperture radar echo signal processing method and device, which are used for extracting initial parameters based on satellite orbit and attitude information data, pre-correcting an original echo signal according to the initial parameters to obtain a pre-corrected echo signal, compensating a distance gain and a azimuth direction pattern based on the pre-corrected echo signal to obtain a compensated echo signal, and performing imaging gain correction on the compensated echo signal to obtain a corrected echo signal. The method can compensate the influence of transmitting power, receiver gain, ADC gain and system noise simultaneously, and combines the distance direction and azimuth direction antenna patterns to realize radiation consistency correction.

Inventors

  • DU SHAOYAN

Assignees

  • 上海辅量成像技术有限公司

Dates

Publication Date
20260512
Application Date
20260414

Claims (10)

  1. 1. A synthetic aperture radar echo signal processing method, comprising the steps of: Extracting initial parameters based on satellite orbit and attitude information data; pre-correcting the original echo signal according to the initial parameters to obtain a pre-corrected echo signal; Performing distance gain compensation and azimuth pattern compensation based on the pre-corrected echo signals to obtain compensated echo signals; and carrying out imaging gain correction on the compensated echo signals to obtain corrected echo signals.
  2. 2. The method as recited in claim 1, further comprising: and carrying out absolute radiation calibration processing on the corrected echo signals to obtain calibration constants.
  3. 3. The method of claim 1 or 2, wherein extracting initial parameters based on satellite orbit and attitude information data comprises: acquiring three-dimensional position, speed and attitude information of a satellite by reading the satellite orbit and attitude information data file; And calculating the pitch angle and the azimuth angle of each pulse according to the satellite orbit, and extracting the transmitting power, the receiver gain, the ADC gain, the distance-oriented antenna pattern and the azimuth-oriented antenna pattern from an auxiliary calibration file of the radar system.
  4. 4. The method according to claim 1, characterized in that the original echo signal is pre-corrected according to the initial parameters: and correcting the original echo signal by using the estimated amplitude and phase errors of the calibration signal, and performing gain correction on the received signal according to the gain and temperature correction factors of the receiver.
  5. 5. The method of claim 1, wherein performing distance gain compensation and azimuth pattern compensation based on the pre-corrected echo signal, the obtaining the compensated echo signal comprises: the pre-corrected echo signals are subjected to distance direction compression by using a matched filter, and are compensated by using a distance direction gain compensation operator, so that compensated signals are obtained; performing fast Fourier transform on the compensated signal to obtain an azimuth spectrum; And compensating according to the azimuth frequency spectrum and the azimuth gain compensation factor to obtain a compensated echo signal.
  6. 6. The method of claim 5, wherein performing imaging gain correction on the compensated echo signal to obtain a corrected echo signal comprises: Converting the compensated signal to a frequency domain through fast Fourier transform, and calculating a gain factor of a matched filter and a white noise gain factor; And adjusting the signal amplitude according to the gain factor and the white noise gain factor, and restoring the frequency domain signal to the time domain to obtain a corrected echo signal.
  7. 7. A synthetic aperture radar echo signal processing device for use in the method of any one of claims 1-6, comprising: The extracting unit is used for extracting initial parameters based on satellite orbit and attitude information data; the pre-correction unit is used for pre-correcting the original echo signal according to the initial parameters to obtain a pre-corrected echo signal; The compensation unit is used for carrying out distance gain compensation and azimuth pattern compensation based on the pre-corrected echo signals to obtain compensated echo signals; And the correction unit is used for carrying out imaging gain correction on the compensated echo signal to obtain a corrected echo signal.
  8. 8. An electronic device comprising a memory and a processor, the memory having stored thereon a program executable on the processor, which when executed by the processor, causes the electronic device to implement the method of any of claims 1-6.
  9. 9. A readable storage medium having a program stored therein, characterized in that the program, when executed, implements the method of any one of claims 1-6.
  10. 10. A computer program product comprising a computer program, characterized in that the computer program, when executed by a processor, implements the method of any of claims 1-6.

Description

Synthetic aperture radar echo signal processing method and device Technical Field The invention relates to the field of radar signal processing, in particular to a synthetic aperture radar echo signal processing method and device. Background SAR (SYNTHETIC APERTURE RADAR ) is used as an active imaging radar system, has the capability of acquiring surface information all weather and all day, and is widely applied to the fields of earth observation, environment monitoring, disaster early warning, national defense safety and the like. The radiation consistency of SAR imaging results is highly dependent on system calibration and correction accuracy, where radiation calibration is a critical step to ensure data reliability and comparability. The purpose of performing radiometric calibration is to eliminate uncertainty caused by system characteristic changes and external environmental factors, so as to stably convert the echo signal into a backscatter coefficient of the target, and ensure that the calibration parameters remain constant. However, existing SAR systems still face several challenges in terms of radiation targeting. First, instability of the system scaling parameters is an important issue. For example, the transmitter power may fluctuate over time and temperature, the gains of the receiver and analog-to-digital converter may drift, and the variability of the system noise power under different operating conditions further affects radiation uniformity. These instability factors directly lead to uneven brightness of the SAR image, severely reducing the radiation consistency. Secondly, the SAR antenna is not ideally flat in the distance and azimuth directions, the distance gain variation due to the difference in incidence angle and the weighting effect of the azimuth pattern on the doppler spectrum are shown as radiation fluctuations or even banding effects in the imaging result. The above problems are particularly pronounced in wide imaging modes (e.g., scanSAR and TOPS), where effective compensation is not performed, which can seriously affect image quality and subsequent quantitative analysis. Some existing methods solve these problems by performing equalization or radiation correction in the image domain, but such methods tend to amplify noise easily, and it is difficult to fully compensate for errors caused by system gain variation and antenna pattern, especially in imaging modes where the sub-aperture difference is significant. Furthermore, the prior art lacks a unified processing framework. The scattered processing mode not only increases the complexity of implementation, but also is difficult to ensure the consistency and stability among the processing links. Therefore, a method and apparatus for processing echo signals of a synthetic aperture radar are needed to improve the above-mentioned problems. Disclosure of Invention The invention aims to provide a synthetic aperture radar echo signal processing method and device, which can realize radiometric calibration in an echo domain before imaging, can compensate transmitting power, receiver gain, ADC gain and system noise at the same time, and can complete radiometric consistency correction by combining an antenna pattern. The invention provides a synthetic aperture radar echo signal processing method, which comprises the steps of extracting initial parameters based on satellite orbit and attitude information data, pre-correcting an original echo signal according to the initial parameters to obtain a pre-corrected echo signal, performing distance gain compensation and azimuth direction pattern compensation based on the pre-corrected echo signal to obtain a compensated echo signal, and performing imaging gain correction on the compensated echo signal to obtain a corrected echo signal. Optionally, the method further comprises the step of carrying out absolute radiation calibration processing on the corrected echo signals to obtain calibration constants. Optionally, the initial parameter extraction based on the satellite orbit and attitude information data comprises the steps of obtaining three-dimensional position, speed and attitude information of a satellite by reading the satellite orbit and attitude information data file, calculating the pitch angle and azimuth angle of each pulse according to the satellite orbit, and extracting the transmitting power, the receiver gain, the ADC gain, the distance-to-antenna directional diagram and the azimuth-to-antenna directional diagram from an auxiliary calibration file of a radar system. Optionally, the original echo signal is pre-corrected according to the initial parameters, namely, the original echo signal is corrected by using the estimated amplitude and the phase error of the calibration signal, and meanwhile, the gain correction is carried out on the received signal according to the gain and the temperature correction factor of the receiver. Optionally, performing distance gain compensation and azimuth