Extraterrestrial object landing measurement radar distance compensation method and system

Abstract

The application provides an extraterrestrial body landing measurement radar distance compensation method and system, comprising: obtaining a radar echo baseband signal, performing FFT processing on the baseband signal, performing CFAR detection based on the FFT processing result, judging whether the radar echo exists, and giving an identification of the existence of the radar echo; according to the identification of the existence of the radar echo, analyzing the amplitude-frequency characteristics of the radar echo, and correcting the amplitude-frequency characteristics of the echo signal in the passband of the filter according to the frequency. The amplitude-frequency characteristics of the corrected radar main lobe echo are used for radar echo signal barycenter estimation processing, the barycenter of the frequency characteristics of the positive and negative frequency modulation echoes is obtained, and the relative extraterrestrial body landing surface distance measurement value is obtained according to the barycenter values of the positive and negative frequency modulation. The incident angle is obtained, and the distance measurement value is corrected according to the barycenter deviation of the incident angle. The application is simple to realize, and can solve the problem that the inconsistent filter passband amplitude-frequency characteristics of the landing measurement radar seriously affect the barycenter estimation of the surface target echo signal.

Description

Technical Field

[0001] This invention relates to the field of distance compensation methods, and in particular to a distance compensation method and system for radar used in extraterrestrial landing measurement. Background Technology

[0002] Extraterrestrial landing measurement radar (LTRP) is used in the detection of extraterrestrial objects. Providing the lander's control system with multiple high-precision ranging and velocity values ​​relative to the surface of the extraterrestrial object along multiple axes is a crucial sensor ensuring a soft landing. The LTRP transmits a linear frequency modulated (LFM) interrupted continuous triangular wave signal with a maximum bandwidth of 500 MHz to the surface of the extraterrestrial object via a transmitting antenna. It then receives the scattered echo signal from the surface via a receiving antenna. Using dechirp technology, the LTRP reduces the bandwidth of the 500 MHz LFM interrupted continuous triangular wave signal to a difference frequency surface target signal within 0.5 MHz. This is followed by down-conversion and a 0.5 MHz bandpass filter to obtain the intermediate frequency signal of the large ground target echo. The signal processor, through digital down-conversion, FFT processing, and a centroid estimation algorithm, can obtain the distance to the ground.

[0003] In practical applications, the projected area of ​​the beam at the same angular interval within the illumination area of ​​an extraterrestrial object varies, and the incident angle on the surface also differs. This results in the echo energy received by the landing measurement radar not being symmetrical about the beam center. The spectral centroid obtained using the centroid estimation method is not the frequency corresponding to the beam center. To achieve unbiased estimation, a centroid correction algorithm has been proposed. However, this centroid correction algorithm only considers the influence of the incident angle and the antenna beam, without considering the influence of the landing measurement radar filter amplitude-frequency characteristics on the spectral centroid extraction. Since the filter bandwidth is generally 3dB, the spectral amplitude difference between the filter's spectral center and the passband edge is 3dB. Furthermore, considering the ripple effect of the filter's passband spectrum, i.e., the modulation of the filter's inconsistency amplitude frequency within the surface target signal of the difference frequency signal, the centroid estimation of the surface target cannot be ignored due to this amplitude modulation. Summary of the Invention

[0004] The purpose of this invention is to provide a method and system for range compensation of extraterrestrial object landing measurement radar, in order to solve the problem that the inconsistency of the passband amplitude-frequency characteristics of landing measurement radar filter seriously affects the centroid estimation of surface target echo signal.

[0005] In view of this, the present invention provides a radar range compensation method for extraterrestrial landing measurement, comprising:

[0006] The radar echo baseband signal after digital downconversion of the intermediate frequency signal is acquired, the baseband signal is processed by FFT, and CFAR detection is performed based on the FFT processing result to determine whether a radar echo exists. When a radar echo exists, an indicator of the presence of the radar echo is given.

[0007] Based on the radar echo presence markers, the amplitude-frequency characteristics of the radar echo are analyzed. The amplitude-frequency characteristics of the radar echo signal within the passband of the landing measurement radar filter are corrected at frequency points to obtain the corrected radar echo signal. The centroid estimation deviation caused by the inconsistency of amplitude-frequency characteristics within the filter passband is corrected.

[0008] The main lobe signal of the surface target echo is extracted from the corrected radar echo signal.

[0009] The centroid of the corrected radar echo main lobe signal is extracted, and the distance measurement value is calculated.

[0010] The system receives incident angle information from the controller and performs centroid correction on the distance measurement value according to the incident angle. This corrects the centroid estimation deviation caused by the asymmetry of the antenna's received echo energy, thus completing radar range compensation.

[0011] Furthermore, the gate center, near-side beamwidth, and far-side beamwidth for the next measurement cycle are calculated from the distance measurement value after the center of gravity correction.

[0012] Further, the baseband signal is subjected to FFT processing, including: performing FFT processing on the positive and negative frequency modulation received signals after dechirp processing and quadrature downconversion, respectively, to obtain the FFT processing results.

[0013] Further, CFAR detection is performed to determine whether radar echo exists, including: opening a detection window with a width of N sampling points near the maximum amplitude of the FFT processing result; if M sampling points within the detection window can pass the detection threshold, N≥M≥1, then the CFAR detection is deemed successful; if no M sampling points within the detection window can pass the detection threshold, then the CFAR detection is deemed unsuccessful.

[0014] Furthermore, the amplitude-frequency characteristics of the radar echo are used to perform amplitude-frequency correction processing on the radar echo signal. Within the passband of the landing measurement radar filter, the amplitude-frequency characteristics of the radar echo are corrected according to frequency to correct the centroid estimation deviation caused by the inconsistency of amplitude-frequency characteristics within the filter passband.

[0015] Furthermore, using the amplitude-frequency characteristics of the echo signal within the passband of the corrected landing measurement radar filter, the main lobe of the radar echo signal is truncated, including:

[0016] First, obtain the gate center, near-side beamwidth, and far-side beamwidth;

[0017] Then, a beam with a near-side width of W is opened near the center of the gate. near The number of sampling points and the beamwidth at the far side of the beam are W.far The main lobe signal detection window at each sampling point.

[0018] Furthermore, the centroid estimation process is performed on the main lobe signal detection window after amplitude-frequency correction to obtain the centroid of the positive and negative frequency-modulated echo signals, and then the distance measurement value relative to the landing surface of the extraterrestrial body is calculated.

[0019] Furthermore, the incident angle information is obtained from the controller, and the distance measurement value is corrected for center of gravity deviation according to the incident angle.

[0020] On the other hand, this invention discloses a radar range compensation system for extraterrestrial landing measurement, comprising:

[0021] The system includes an FFT processing module, a CFAR detection module, an amplitude-frequency correction module, a main lobe signal truncation module, a centroid estimation module, a distance measurement calculation module, a centroid deviation correction module, and a distance measurement feedback module.

[0022] The measurement results of the FFT processing module are output to the CFAR detection module, the detection results of the CFAR detection module are output to the amplitude-frequency correction module, the correction results of the amplitude-frequency correction module are output to the main lobe signal truncation module, the truncation results of the main lobe signal truncation module are output to the centroid estimation module, the estimation results of the centroid estimation module are output to the distance measurement value calculation module, the calculation results of the distance measurement value calculation module are output to the centroid deviation correction module, the correction results of the centroid deviation correction module are output to the distance measurement value feedback module, and the feedback results of the distance measurement value feedback module are output to the amplitude-frequency correction module.

[0023] The present invention achieves the following significant beneficial effects:

[0024] The method is simple to implement and has high measurement accuracy. It includes: acquiring the radar echo baseband signal after digital down-conversion of the intermediate frequency signal; performing FFT processing on the baseband signal; performing CFAR detection based on the FFT results to determine the presence of a radar echo; if no echo is found, the process ends; otherwise, an indicator of radar echo presence is given; analyzing the amplitude-frequency characteristics of the radar echo based on the indicator, and performing amplitude correction on the amplitude-frequency characteristics of the echo signal within the filter passband according to frequency; acquiring the gate center, near-side beamwidth, and far-side beamwidth to obtain the main lobe echo signal with the corrected amplitude-frequency characteristics; using the amplitude-frequency characteristics of the corrected radar main lobe echo, performing radar echo signal centroid estimation processing to obtain the centroid of the frequency characteristics of the positive and negative frequency-modulated radar echoes; and calculating the distance measurement value relative to the landing surface of an extraterrestrial object based on the centroid values ​​of the positive and negative frequency modulations; acquiring the incident angle and correcting the centroid deviation of the distance measurement value according to the incident angle. The gate center, near-side beamwidth, and far-side beamwidth for the next measurement cycle are calculated from the distance measurement value after the center of gravity correction. Attached Figure Description

[0025] Figure 1 This is a flowchart of a radar range compensation method for extraterrestrial body landing measurement according to the present invention;

[0026] Figure 2 This is a schematic diagram of the structure of a radar range compensation method for extraterrestrial landing measurement according to the present invention.

[0027] Illustration of reference numerals in the attached diagram:

[0028] 1—FFT processing module; 2—CFAR detection module; 3—Amplitude-frequency correction module; 4—Main lobe signal truncation module

[0029] 5—Center of Gravity Estimation Module; 6—Distance Measurement Calculation Module; 7—Center of Gravity Deviation Correction Module

[0030] 8—Distance Measurement Feedback Module

[0031] Specific examples

[0032] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become clearer from the following description and claims. It should be noted that the drawings are all in a very simplified form and are not to a precise scale, and are only used to facilitate and clarify the illustration of the embodiments of the present invention.

[0033] It should be noted that, in order to clearly illustrate the content of this invention, several embodiments are provided to further explain different implementations of the invention. These embodiments are enumerated rather than exhaustive. Furthermore, for the sake of brevity, content mentioned in the preceding embodiments is often omitted in the following embodiments. Therefore, content not mentioned in the later embodiments can be referred to in the preceding embodiments.

[0034] While this invention can be extended with various modifications and substitutions, and the specification provides specific embodiments with detailed illustrations, it should be understood that the inventors' intention is not to limit the invention to the specific embodiments described. On the contrary, the inventors' intention is to protect all improvements, equivalent substitutions, and modifications made within the spirit or scope defined by this claim. The same component numbers may be used in all figures to represent the same or similar parts.

[0035] Example 1

[0036] Please refer to Figure 1 The present invention provides a radar range compensation method for extraterrestrial landing measurement, comprising:

[0037] Step S101: Obtain the radar echo baseband signal after digital downconversion of the intermediate frequency signal, perform FFT processing on the baseband signal, perform CFAR detection based on the FFT processing result, determine whether there is a radar echo, and when there is a radar echo, give an indicator of the presence of the radar echo.

[0038] Step S102: Based on the indicator of the presence of the radar echo, analyze the amplitude-frequency characteristics of the radar echo, perform amplitude-frequency correction on the amplitude-frequency characteristics of the radar echo within the passband of the landing measurement radar filter, and obtain the corrected radar echo signal; extract the main lobe signal detection window of the echo.

[0039] Step S103: Using the amplitude-frequency characteristics of the main lobe signal of the echo after amplitude-frequency correction, perform radar echo signal centroid estimation processing to obtain the centroid of the frequency characteristics of the radar echo, and then calculate the distance measurement value relative to the landing surface of the extraterrestrial body.

[0040] Step S104: Analyze the distance measurement value and correct the center of gravity deviation according to the incident angle;

[0041] Step S105: Calculate the gate center, near-side beamwidth, and far-side beamwidth for the next measurement cycle from the distance measurement value after center-of-gravity correction.

[0042] In one embodiment of this application, specifically, the baseband signal is subjected to FFT processing, which includes: performing FFT processing on the positive and negative frequency modulation received signals after dechirp processing and quadrature downconversion, respectively, to obtain the FFT processing result.

[0043] In one embodiment of this application, specifically, CFAR detection is performed to determine whether a radar echo exists, including: opening a detection window with a width of N sampling points near the maximum amplitude of the FFT processing result; if it is determined that M sampling points within the detection window can pass the detection threshold, N≥M≥1, then the CFAR detection is determined to be passed; if no M sampling points within the detection window can pass the detection threshold, then the CFAR detection is determined to be failed.

[0044] In one embodiment of this application, specifically, amplitude-frequency correction processing of radar echo signals is performed, and the amplitude-frequency characteristics of the radar echo are corrected according to frequency within the passband of the landing measurement radar filter.

[0045] In one embodiment of this application, specifically, the main lobe of the radar echo signal is truncated using the amplitude-frequency characteristics of the echo signal within the passband of the corrected landing measurement radar filter, including:

[0046] First, obtain the gate center, near-side beamwidth, and far-side beamwidth;

[0047] Then, a beam with a near-side width of W is opened near the center of the gate. near The number of sampling points and the beamwidth at the far side of the beam are W. far A main lobe signal detection window is set up at each sampling point, and amplitude-frequency correction is performed within this detection window.

[0048] In one embodiment of this application, specifically, the centroid estimation processing is performed on the main lobe signal detection window after amplitude-frequency correction to obtain the centroid of the positive and negative frequency-modulated echo signals, and then the distance measurement value relative to the landing surface of the extraterrestrial body is calculated.

[0049] In one embodiment of this application, specifically, incident angle information is obtained from the controller, and the distance measurement value is corrected for center of gravity deviation according to the incident angle.

[0050] In one embodiment of this application, the method further includes: calculating the gate center, near-side beamwidth, and far-side beamwidth of the next measurement cycle from the distance measurement value after the center of gravity correction.

[0051] In summary, this embodiment provides a radar range compensation method for extraterrestrial landing measurement, comprising: acquiring the radar echo baseband signal after digital down-conversion of the intermediate frequency signal; performing FFT processing on the baseband signal; performing CFAR detection based on the FFT processing result to determine whether a radar echo exists; if not, the process ends; otherwise, an indicator indicating the presence of a radar echo is given; analyzing the amplitude-frequency characteristics of the radar echo according to the indicator, and performing amplitude correction on the amplitude-frequency characteristics of the echo signal within the filter passband according to frequency; acquiring the gate center, near-side beamwidth, and far-side beamwidth to obtain the main lobe echo signal with the corrected amplitude-frequency characteristics; using the amplitude-frequency characteristics of the corrected radar main lobe echo to perform radar echo signal centroid estimation processing to obtain the centroid of the frequency characteristics of the positive and negative frequency-modulated radar echoes, and calculating the distance measurement value relative to the extraterrestrial landing surface based on the centroid values ​​of the positive and negative frequency modulations; acquiring the incident angle, and performing centroid deviation correction on the distance measurement value according to the incident angle. The gate center, near-side beamwidth, and far-side beamwidth for the next measurement cycle are calculated from the distance measurement value after centroid correction. This invention is simple to implement and can solve the problem that inconsistencies in the passband amplitude-frequency characteristics of landing measurement radar filters severely affect the centroid estimation of surface target echo signals.

[0052] Example 2

[0053] This invention improves the accuracy of surface target centroid estimation, i.e., the accuracy of range measurement, by correcting the amplitude-frequency error of the surface target echo signal caused by the inconsistency of the amplitude-frequency characteristics within the passband of the landing measurement radar filter. The extraterrestrial body landing measurement radar range compensation method according to this invention includes the following steps:

[0054] The system comprises: FFT processing module 1, CFAR detection module 2, amplitude-frequency correction module 3, main lobe signal truncation module 4, centroid estimation module 5, distance measurement value calculation module 6, centroid deviation correction module 7, and distance measurement value feedback module 8.

[0055] The measurement result of the FFT processing module 1 is output to the CFAR detection module 2, the detection result of the CFAR detection module 2 is output to the amplitude-frequency correction module 3, the correction result of the amplitude-frequency correction module 3 is output to the main lobe signal truncation module 4, the truncation result of the main lobe signal truncation module 4 is output to the centroid estimation module 5, the estimation result of the centroid estimation module 5 is output to the distance measurement value calculation module 6, the calculation result of the distance measurement value calculation module 6 is output to the centroid deviation correction module 7, the correction result of the centroid deviation correction module 7 is output to the distance measurement value feedback module 8, and the feedback result of the distance measurement value feedback module 8 is output to the amplitude-frequency correction module 3.

[0056] The amplitude-frequency correction module 3 corrects the amplitude-frequency error of the surface target echo signal caused by the inconsistency of amplitude-frequency characteristics within the passband of the landing measurement radar filter, thereby further improving the accuracy of the surface target centroid estimation, i.e. the accuracy of the range measurement value.

[0057] The center of gravity deviation correction module 7 further improves the accuracy of distance measurement by correcting the center of gravity deviation caused by the asymmetry of the beam center axis of the echo signal energy.

[0058] The execution system for each step of the preferred embodiment of the present invention will be described in detail below:

[0059] In one embodiment, the FFT processing module 1 performs N operations on the positive and negative frequency-modulated received signals s(t) after dechirp processing and quadrature downconversion. FFT Pointwise FFT processing yields the FFT result S(f), as shown in the following formula:

[0060] S(f) = FFT{s(t)}

[0061] Equation (1);

[0062] In one embodiment, the CFAR detection module 2 performs CFAR detection on the FFT processing result S(f). A detection window with a width of N sampling points is opened near the maximum amplitude of S(f). If M sampling points within the detection window are determined to pass the detection threshold (N≥M≥1), then the CFAR detection is deemed successful. If no M sampling points within the detection window are determined to pass the detection threshold, then the CFAR detection is deemed unsuccessful.

[0063] In one embodiment, after CFAR detection, the amplitude-frequency correction module 3 performs amplitude-frequency compensation on |S(f)| within the range of -250kHz ≤ f ≤ 250kHz to obtain |S(f)|. bc :

[0064] |S(f)| bc =|S(f)|·Coef f (f), -250kHz≤f≤250kHz

[0065] Equation (2); where Coef f (f) represents the amplitude-frequency response correction coefficients within the passband of the landing measurement radar filter, which are obtained as follows:

[0066] The landing measurement radar is powered on but not operational, acquiring an intermediate frequency (IF) signal containing only thermal noise. This IF signal undergoes orthogonal down-conversion and is then used to analyze the baseband signal s. N (t) then proceed to N FFT Point FFT processing yields the FFT result S. N (f), the formula is as follows:

[0067] S N (f)=FFT{s N (t)}

[0068] Equation (3);

[0069] Extract |S| within the range of -250kHz ≤ f ≤ 250kHz N (f)|, and obtain S through filtering. lpf (f):

[0070] S lpf (f) = filter(|S N (f)|), -250kHz≤f≤250kHz

[0071] Equation (4); where filter() is the filtering function;

[0072] For S lpf (f) is normalized to obtain S1(f):

[0073]

[0074] S max =max(S) lpf (f)), -250kHz≤f≤250kHz

[0075] Equation (5); where max() is the function to find the maximum value;

[0076] The correction coefficient Coef for the amplitude-frequency response is obtained by normalizing S1(f).f (f):

[0077]

[0078] In one embodiment, the gate center k is calculated based on the distance measurement feedback module 8. Z Beam near-side width W near and beam width W far The main lobe signal truncation module 4 is located at the center k of the gate. Z Open a beam with a near-side width of W nearby near The number of sampling points and the beamwidth at the far side of the beam are W. far The main lobe signal detection window at each sampling point.

[0079] In one embodiment, the centroid estimation module 5 performs centroid estimation processing in the main lobe signal detection window to obtain the centroid of the echo signal.

[0080]

[0081] Equation (7); The range of FFT frequency points of the main lobe signal m∈[R left ,R right ];k Z It is negative in positive frequency modulation, k Z It is a positive number during negative frequency modulation; left radius Right radius P n The noise mean is P, which is calculated outside the detection window. n :

[0082]

[0083] Equation (8); where K is W n The number of statistics; the range of noise statistics Round[] is for rounding to the nearest integer, and N is a constant. y ≥10, Δf FFT This represents the frequency resolution of the FFT.

[0084] The centroid of the actual echo signal The average of the centroids of the positive and negative frequency-modulated echo signals:

[0085]

[0086] Equation (9); where, The center of gravity of the positive frequency modulated echo signal; It is the centroid of the negative frequency modulated echo signal.

[0087] In one embodiment, the distance measurement calculation module 6 calculates the distance measurement value based on the result calculated by the centroid estimation module 5. The distance measurement value R is calculated using the following formula:

[0088]

[0089] Equation (10); where k LFM denoted as , where is the slope of the linear frequency modulated signal; c is the speed of light.

[0090] In one embodiment, the center of gravity deviation correction module 7 corrects the center of gravity estimation deviation. Based on the distance measurement value R calculated by the distance measurement value calculation module 6, the corrected distance measurement value R is obtained. bc :

[0091] R bc =R×Coef R (θ)

[0092] Equation (11); where θ is the incident angle of the antenna beam center; Coef R (θ) is the centroid estimation deviation correction coefficient, as follows:

[0093]

[0094] Equation (12); where 1°≤θ min ≤45°, 60°≤θ min ≤85°; α and β are the antenna's elevation and azimuth angles, respectively. 3dB β 3dB These are the 3dB beamwidth in the elevation direction and the 3dB beamwidth in the azimuth direction of the antenna, respectively. Let be the angle of incidence of the antenna on a surface element of an extraterrestrial object, as shown in the following formula:

[0095]

[0096] In one embodiment, the beam center and beamwidth for the next measurement cycle are calculated by the distance measurement feedback module 8.

[0097] In the first measurement cycle after the start of measurement or after invalid data, the frequency point with the maximum amplitude of S(f) is taken as the beam center k. Z .

[0098] After the kth measurement period, k≥2, with R of the kth measurement period bc (k) Calculate the beam center k for the next measurement cycle. Z :

[0099]

[0100] The near-side beamwidth W near and beam width W far The solution formula is as follows:

[0101]

[0102] Among them, the constants are 0.45≤η1≤0.5, 0.5≤η2≤0.8, and 2≤η3≤10.

[0103] In summary, this invention improves the accuracy of surface target centroid estimation, i.e., the accuracy of range measurement, by correcting the amplitude-frequency error of the surface target echo signal caused by the inconsistency of amplitude-frequency characteristics within the passband of the landing measurement radar filter.

[0104] As can be seen from the above description, the embodiments of this application achieve the following technical effects:

[0105] The method is simple to implement and has high measurement accuracy. It includes: acquiring the radar echo baseband signal after digital down-conversion of the intermediate frequency signal; performing FFT processing on the baseband signal; performing CFAR detection based on the FFT results to determine the presence of a radar echo; if no echo is found, the process ends; otherwise, an indicator of radar echo presence is given; analyzing the amplitude-frequency characteristics of the radar echo based on the indicator, and performing amplitude correction on the amplitude-frequency characteristics of the echo signal within the filter passband according to frequency; acquiring the gate center, near-side beamwidth, and far-side beamwidth to obtain the main lobe echo signal with the corrected amplitude-frequency characteristics; using the amplitude-frequency characteristics of the corrected radar main lobe echo, performing radar echo signal centroid estimation processing to obtain the centroid of the frequency characteristics of the positive and negative frequency-modulated radar echoes; and calculating the distance measurement value relative to the landing surface of an extraterrestrial object based on the centroid values ​​of the positive and negative frequency modulations; acquiring the incident angle and correcting the centroid deviation of the distance measurement value according to the incident angle. The gate center, near-side beamwidth, and far-side beamwidth for the next measurement cycle are calculated from the distance measurement value after the center of gravity correction.

[0106] Based on the technical solution and concept of this invention, any other suitable modifications may be made. All such substitutions, adjustments, and improvements should be understood by those skilled in the art to fall within the scope of protection of the appended claims.

Claims

1. A method for distance compensation of radar for measuring landing on extraterrestrial objects, characterized in that, include: The radar echo baseband signal after digital downconversion of the intermediate frequency signal is acquired, the baseband signal is processed by FFT, and CFAR detection is performed based on the FFT processing result to determine whether a radar echo exists. When a radar echo exists, an indicator of the presence of the radar echo is given. Based on the radar echo presence markers, the amplitude-frequency characteristics of the radar echo are analyzed, and the amplitude-frequency characteristics of the radar echo signal within the passband of the landing measurement radar filter are corrected according to frequency points to obtain the corrected radar echo signal. Extract the main lobe signal of the surface target echo from the corrected radar echo signal; The centroid of the corrected radar echo main lobe signal is extracted, and the distance measurement value is calculated. The system receives incident angle information from the controller and performs centroid correction on the distance measurement value according to the incident angle. This corrects the centroid estimation deviation caused by the asymmetry of the antenna's received echo energy, thus completing radar range compensation.

2. The radar range compensation method for extraterrestrial landing measurement according to claim 1, characterized in that, Also includes: The gate center, near-side beamwidth, and far-side beamwidth for the next measurement cycle are calculated from the distance measurement value after the center of gravity correction.

3. The radar range compensation method for extraterrestrial landing measurement according to claim 1, characterized in that, The baseband signal is subjected to FFT processing, specifically including: performing FFT processing on the positive and negative frequency modulation received signals after dechirp processing and quadrature downconversion, respectively, to obtain the FFT processing results.

4. The radar range compensation method for extraterrestrial landing measurement according to claim 3, characterized in that, Performing CFAR detection to determine the presence of radar echoes specifically includes: opening a region of width [value missing] near the maximum amplitude of the FFT processing result. A detection window for each sampling point; if a determination is made within that detection window... Each sampling point can pass the detection threshold. If it passes the CFAR test, then it is considered to have passed; if it does not pass the test in the detection window... If a sampling point passes the detection threshold, it is determined that it has not passed the CFAR detection.

5. The radar range compensation method for extraterrestrial landing measurement as described in claim 4, characterized in that, Using the amplitude-frequency characteristics of the radar echo, amplitude-frequency correction processing of the radar echo signal is performed. Within the passband of the landing measurement radar filter, the amplitude-frequency characteristics of the radar echo are corrected according to frequency to correct the centroid estimation deviation caused by the inconsistency of amplitude-frequency characteristics within the filter passband.

6. The radar range compensation method for extraterrestrial landing measurement according to claim 5, characterized in that, Extracting the main lobe signal of the surface target echo from the corrected radar echo signal specifically includes: using the amplitude-frequency characteristics of the echo signal within the passband of the corrected landing measurement radar filter to extract the main lobe of the radar echo signal. First, obtain the gate center, near-side beamwidth, and far-side beamwidth; Then, a beam with a near-side width of [value missing] is opened near the center of the gate. The number of sampling points and the beamwidth at the far side are: The main lobe signal detection window at each sampling point.

7. The radar range compensation method for extraterrestrial landing measurement according to claim 6, characterized in that, The centroid of the corrected radar echo main lobe signal is extracted, and the range measurement value is calculated, specifically including: The centroid estimation process is performed on the main lobe signal detection window after amplitude-frequency correction to obtain the centroid of the positive and negative frequency-modulated echo signals, and then the distance measurement value relative to the landing surface of the extraterrestrial object is calculated.

8. A system for applying the radar range compensation method for extraterrestrial body landing measurement as described in claim 1, characterized in that, include: The system includes an FFT processing module, a CFAR detection module, an amplitude-frequency correction module, a main lobe signal truncation module, a centroid estimation module, a distance measurement calculation module, a centroid deviation correction module, and a distance measurement feedback module. The measurement results of the FFT processing module are output to the CFAR detection module, the detection results of the CFAR detection module are output to the amplitude-frequency correction module, the correction results of the amplitude-frequency correction module are output to the main lobe signal truncation module, the truncation results of the main lobe signal truncation module are output to the centroid estimation module, the estimation results of the centroid estimation module are output to the distance measurement value calculation module, the calculation results of the distance measurement value calculation module are output to the centroid deviation correction module, the correction results of the centroid deviation correction module are output to the distance measurement value feedback module, and the feedback results of the distance measurement value feedback module are output to the amplitude-frequency correction module.

9. The system according to claim 8, characterized in that, The FFT processing module processes the positive and negative frequency-modulated received signals after dechirp processing and quadrature downconversion. Perform separately Point FFT processing is performed to obtain the FFT result. The formula is as follows: （1）。 10. The system according to claim 9, characterized in that, CFAR detection module's FFT processing results Perform CFAR detection, in Open a space with a width near the maximum amplitude. A detection window for each sampling point; if a determination is made within that detection window... Each sampling point can pass the detection threshold. If it passes the CFAR test, then it is considered to have passed; if it does not pass the test in the detection window... If a sampling point passes the detection threshold, it is determined that it has not passed the CFAR detection.

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