CN-116184384-B - Method and system for compensating distance of extraterrestrial celestial body landing measurement radar

CN116184384BCN 116184384 BCN116184384 BCN 116184384BCN-116184384-B

Abstract

The invention provides an extraterrestrial celestial body landing measurement radar distance compensation method and system, which comprise the steps of obtaining radar echo baseband signals, carrying out FFT processing on the baseband signals, carrying out CFAR detection based on FFT processing results, judging whether radar echoes exist or not, giving out the identification of the existence of the radar echoes, analyzing the amplitude-frequency characteristics of the radar echoes according to the identification of the existence of the radar echoes, and carrying out amplitude correction on the amplitude-frequency characteristics of echo signals in a filter passband according to frequency. And carrying out radar echo signal gravity center estimation processing by using the amplitude-frequency characteristics of the corrected radar main lobe echo to obtain the gravity center of the frequency characteristics of the positive and negative frequency modulation echoes of the radar, and calculating according to the gravity center values of the positive and negative frequency modulation to obtain a distance measurement value relative to the landing surface of the extraterrestrial celestial body. And acquiring an incident angle, and correcting gravity center deviation of the distance measurement value according to the incident angle. The method is simple to realize, and can solve the problem that the center of gravity estimation of the surface target echo signal is seriously affected by inconsistent passband amplitude-frequency characteristics of the landing measurement radar filter.

Inventors

XU QIUFENG
SUN WU
JIA XUEZHEN
LIU JIA
Ke Tenglun
DING KAISHENG
CHEN XIAOYU
CHEN RUIRONG

Assignees

北京遥感设备研究所

Dates

Publication Date: 20260508
Application Date: 20220908

Claims (10)

1. An extraterrestrial celestial body landing measurement radar distance compensation method, characterized by comprising: Acquiring a radar echo baseband signal of an intermediate frequency signal after digital down conversion, performing FFT processing on the baseband signal, performing CFAR detection based on the FFT processing result, judging whether a radar echo exists, and giving an identifier of the existence of the radar echo when the radar echo exists; Analyzing amplitude-frequency characteristics of the radar echo according to the identification of the radar echo, and carrying out amplitude correction on the amplitude-frequency characteristics of the radar echo signal in the passband of the radar filter according to frequency points to obtain a corrected radar echo signal; intercepting a surface target echo main lobe signal from the corrected radar echo signal; extracting the gravity center of the corrected radar echo main lobe signal, and calculating to obtain a distance measurement value; And receiving incident angle information from a controller, carrying out gravity center correction on the distance measurement value according to the incident angle, correcting gravity center estimation deviation caused by the non-axisymmetry of the received wave energy of the antenna, and completing radar distance compensation.
2. The method of claim 1, further comprising calculating a gate center, a beam proximal width, and a beam distal width for a next measurement cycle from the center-of-gravity corrected range measurements.
3. The method for compensating the distance of the radar for the landing measurement of the extraterrestrial celestial body according to claim 1, wherein the method for compensating the distance of the radar for the landing measurement of the extraterrestrial celestial body is characterized by performing FFT processing on the baseband signals, and specifically comprises performing FFT processing on positive and negative frequency modulation received signals subjected to dechirp processing and quadrature down-conversion respectively to obtain FFT processing results.
4. The method for compensating for radar distance for extraterrestrial celestial body landing measurement of claim 3, wherein the step of performing CFAR detection to determine whether radar echo is present comprises opening up a width of the FFT processing result in the vicinity of a maximum amplitude A detection window of a plurality of sampling points, if it is judged that there is a detection window The individual sample points can pass a detection threshold, It is determined to pass CFAR detection if there is no detection window And if the sampling points pass the detection threshold, judging that the CFAR detection is not passed.
5. The method for compensating for the distance of an extraterrestrial celestial body landing measurement radar according to claim 4, wherein the amplitude-frequency characteristic of the radar echo is used for carrying out amplitude-frequency correction processing on the radar echo signal, the amplitude-frequency characteristic of the radar echo is corrected in the passband of the landing measurement radar filter according to frequency, and the estimated deviation of the center of gravity due to the inconsistency of the amplitude-frequency characteristics in the passband of the filter is corrected.
6. The method for compensating for radar range in extraterrestrial celestial body landing measurement according to claim 5, wherein intercepting the main lobe signal of the target echo in the corrected radar echo signal comprises intercepting the main lobe of the radar echo signal by using amplitude-frequency characteristics of the echo signal in the passband of the corrected landing measurement radar filter, Firstly, acquiring a waveguide gate center, a beam proximal width and a beam distal width; Then, a beam is opened up near the center of the wave gate to have a near-side width of The distal width of each sampling point and beam is And main lobe signal detection windows of the sampling points.
7. The method for compensating for radar distance for extraterrestrial celestial body landing measurement according to claim 6, wherein the extracting of the center of gravity of the corrected radar echo main lobe signal, and the calculating of the distance measurement value, specifically comprise: and carrying out gravity center estimation processing on the amplitude-frequency corrected main lobe signal detection window to obtain the gravity center of the positive and negative frequency modulation echo signals, and then calculating to obtain a distance measurement value relative to the landing surface of the earth celestial body.
8. A system for applying the method for radar range compensation for extraterrestrial celestial body landing measurement of claim 1, comprising: FFT processing module, CFAR detection module, amplitude frequency correction module, main lobe signal interception module, focus estimation module, distance measurement value calculation module, focus deviation correction module and distance measurement value feedback module, wherein: The measurement result of the FFT processing module is output to the CFAR detection module, the detection result of the CFAR detection module is output to the amplitude-frequency correction module, the correction result of the amplitude-frequency correction module is output to the main lobe signal interception module, the interception result of the main lobe signal interception module is output to the gravity center estimation module, the estimation result of the gravity center estimation module is output to the distance measurement value calculation module, the calculation result of the distance measurement value calculation module is output to the gravity center deviation correction module, the correction result of the gravity center deviation correction module is output to the distance measurement value feedback module, and the feedback result of the distance measurement value feedback module is output to the amplitude-frequency correction module.
9. The system of claim 8 wherein the FFT processing module processes and quadrature downconverts the dechirp processed positive and negative fm received signals Respectively do Performing point FFT processing to obtain FFT processing results The formula is as follows: (1)。
10. The system of claim 9, wherein the CFAR detection module processes the FFT result CFAR detection is performed in A width is opened up near the maximum amplitude A detection window of a plurality of sampling points, if it is judged that there is a detection window The individual sample points can pass a detection threshold, It is determined to pass CFAR detection if there is no detection window And if the sampling points pass the detection threshold, judging that the CFAR detection is not passed.

Description

Method and system for compensating distance of extraterrestrial celestial body landing measurement radar Technical Field The invention relates to the technical field of distance compensation methods, in particular to a method and a system for compensating the distance of an extraterrestrial celestial body landing measurement radar. Background The landing measurement radar of the extraterrestrial celestial body is applied to the detection of the extraterrestrial celestial body, and provides a plurality of high-precision ranging and speed measuring values relative to the surface of the extraterrestrial celestial body in the axial direction to a land control system, wherein the high-precision ranging and speed measuring values are key sensors for ensuring that the lander lands on the surface of the extraterrestrial celestial body softly. The landing measurement radar transmits a linear frequency modulation interruption continuous triangular wave signal with the bandwidth of 500MHz to the surface of the earth celestial body through a transmitting antenna, receives an earth celestial body surface scattering echo signal through a receiving antenna, reduces the bandwidth of the linear frequency modulation interruption continuous triangular wave signal with the bandwidth of 500MHz to a difference frequency surface target signal within 0.5MHz through dechirp technology, and acquires a large ground target echo intermediate frequency signal through down-conversion and 0.5MHz band-pass filtering. The signal processor can acquire the ground distance through digital down-conversion, FFT processing and a gravity center estimation algorithm. In practical application, the projection areas of the beams at the same angle interval in the irradiation area of the surface of the extraterrestrial celestial body are different, and the incidence angles on the surface are different, so that the echo energy received by the landing measurement radar is not symmetrical by taking the beam center as an axis. The center of gravity of the spectrum obtained by the center of gravity estimation method is not the frequency corresponding to the beam center, and in order to achieve unbiased estimation, a center of gravity correction algorithm has been proposed. However, the barycenter correction algorithm only considers the influence of the incident angle and the antenna wave beam, but does not consider the influence of the amplitude-frequency characteristic of the landing measurement radar filter on the extraction of the center of spectrum barycenter, and because the bandwidth of the filter is generally 3dB bandwidth, the spectral amplitudes of the center of the filter spectrum and the edges of the passband are 3dB different, and then considers the ripple influence of the filter passband spectrum, namely, the inconsistent amplitude frequency of the filter is modulated in the surface target signal of the difference frequency signal, and the barycenter estimation of the surface target is not negligible. Disclosure of Invention The invention aims to provide a distance compensation method and a system for an extraterrestrial celestial body landing measurement radar, which are used for solving the problem that the center of gravity estimation of a target echo signal is seriously affected by inconsistent passband amplitude-frequency characteristics of a landing measurement radar filter. In view of the above, the present invention provides an extraterrestrial celestial body landing measurement radar distance compensation method, comprising: Acquiring a radar echo baseband signal of an intermediate frequency signal after digital down conversion, performing FFT processing on the baseband signal, performing CFAR detection based on the FFT processing result, judging whether a radar echo exists, and giving an identifier of the existence of the radar echo when the radar echo exists; according to the identification of the radar echo, analyzing the amplitude-frequency characteristic of the radar echo, carrying out amplitude correction on the amplitude-frequency characteristic of the radar echo signal in the passband of the filter of the land-based radar according to frequency points to obtain a corrected radar echo signal, and correcting the estimated deviation of the center of gravity caused by inconsistent amplitude-frequency characteristics in the passband of the filter. And intercepting a surface target echo main lobe signal from the corrected radar echo signal. And extracting the gravity center of the corrected radar echo main lobe signal, and calculating to obtain a distance measurement value. And receiving incident angle information from a controller, carrying out gravity center correction on the distance measurement value according to the incident angle, correcting gravity center estimation deviation caused by the non-axisymmetry of the received wave energy of the antenna, and completing radar distance compensation. Further, the center of the wave gate