Scatterometer in-orbit satellite-ground integrated calibration method, system, equipment, medium and product

Abstract

The invention discloses a scatterometer in-orbit satellite-ground integrated calibration method, system and device, a medium and a product, and relates to the field of radar calibration, and the method comprises the steps: screening scatterometer observation signals, carrying out the quality inspection of the downloading data of a scatterometer, extracting the quality inspection data in an external calibration working time range, and carrying out the detection of the quality inspection data in the external calibration working time range; determining a pitch angle and an azimuth angle of the satellite-to-earth connection line according to the quality inspection data, performing calibration by combining with a scatterometer observation signal received by a ground calibration station to obtain an antenna gain of the scatterometer, and performing interpolation on the antenna gain of the scatterometer to obtain a satellite-to-earth connection line; determining an actual antenna pattern of the scatterometer and determining a comparison result of the actual antenna pattern and an antenna pattern measured in a laboratory before emission; and calculating a theoretical backscattering coefficient according to the antenna gain and the amplification gain of the active calibrator, determining an actual backscattering coefficient according to the quality inspection data and the antenna gain of the scatterometer in combination with a measured antenna pattern, further determining an absolute calibration coefficient, and completing a calibration task. According to the invention, the calibration precision and the inspection capability of the scatterometer are improved.

Description

Technical Field

[0001] The present application relates to the field of radar calibration, and in particular to an on-orbit satellite-ground integrated calibration method, system, equipment, medium and product for a scatterometer. Background Art

[0002] The scatterometer carried by the Fengyun-3E satellite (FY-3E) - Wind Field Measurement Radar (WindRAD) is the first active remote sensing instrument of China's Fengyun series of meteorological satellites. Its main working goal is to conduct all-weather, all-day, high-precision measurements of global sea surface wind field vectors (including wind speed and wind direction). After the wind field measurement radar is launched into orbit, a combination of internal calibration and external calibration is used to achieve high-precision calibration. Internal calibration is mainly used to eliminate the impact of changes in transmitter transmission power and receiver gain on the measurement; external calibration is field calibration, which uses ground calibration targets to make absolute corrections to the wind field measurement radar observation data to eliminate some difficult-to-measure and difficult-to-estimate quantities that are not taken into account in the antenna pattern and radar equations.

[0003] The main work of external calibration is completed by satellite-ground cooperation after the wind field measurement radar is launched into orbit. External calibration is to calibrate the radar on the satellite using a target with a known radar scattering cross section to obtain the true target backscatter coefficient. The method of calibration using a distributed target with stable ground scattering and a passive point target standard reference reflector cannot meet the accuracy requirements of the scatterometer external calibration. Summary of the invention

[0004] The purpose of this application is to provide a scatterometer on-orbit satellite-ground integrated calibration method, system, equipment, medium and product to improve the calibration accuracy of the scatterometer.

[0005] To achieve the above objectives, this application provides the following solutions:

[0006] In a first aspect, the present application provides a scatterometer on-orbit satellite-ground integrated calibration method, comprising:

[0007] Acquire the downlink data of the scatterometer; the downlink data includes the scatterometer observation signal, observation time and scanning angle;

[0008] According to the weather forecast data, the scatterometer observation signal is screened to obtain a screened scatterometer observation signal; the weather forecast data includes water vapor, cloud cover and rainfall; the screened scatterometer observation signal is a scatterometer observation signal under clear sky conditions;

[0009] Performing quality inspection on the downlink data of the scatterometer to obtain scatterometer quality inspection data, and segmenting the scatterometer quality inspection data based on the external calibration working time range to extract the scatterometer quality inspection data within the external calibration working time range;

[0010] Determine the elevation angle and azimuth angle of the satellite-to-ground line according to the scatterometer quality inspection data within the external calibration working time range; the satellite-to-ground line is a line connecting the coordinates of the satellite and the ground calibration station;

[0011] Calibration is performed according to the elevation angle and azimuth angle of the satellite-to-ground line and the scatterometer observation signal received by the ground calibration station to obtain a calibration result; the calibration result is the antenna gain of the scatterometer at the matching point; the matching point is a time matching point that meets the time difference threshold; the time matching point is obtained by matching the effective pulse signal with the elevation angle and azimuth angle of the satellite-to-ground line through time; the effective pulse signal is determined based on the scatterometer observation signal received by the ground calibration station;

[0012] Interpolating the antenna gain of the scatterometer according to the filtered scatterometer observation signal and the elevation angle and azimuth angle of the satellite-to-ground line to determine the actual antenna pattern of the scatterometer;

[0013] Comparing the actual antenna pattern with the antenna pattern of the scatterometer measured in the ground laboratory to determine a comparison result;

[0014] Determine the theoretical backscatter coefficient of the active calibrator according to the antenna gain and amplification gain of the active calibrator, and determine the actual backscatter coefficient of the active calibrator according to the scatterometer quality inspection data and calibration results within the working time range of the external calibration, combined with the antenna radiation pattern of the scatterometer measured in the ground laboratory; the antenna gain of the active calibrator is measured in the ground laboratory;

[0015] According to the theoretical backscatter coefficient of the active calibrator and the actual backscatter coefficient of the active calibrator, an absolute calibration coefficient is determined to complete a calibration task; the calibration task includes determining the comparison result and the absolute calibration coefficient.

[0016] Optionally, determining a valid pulse signal based on a scatterometer observation signal received by a ground calibration station specifically includes:

[0017] Down-convert the scatterometer observation signal received by the ground calibration station to obtain a baseband signal;

[0018] Performing matched filtering on the baseband signal to obtain a matched filtered signal;

[0019] Performing pulse compression on the matched filtered signal using a matching function to obtain a pulse compressed complex signal;

[0020] Determining the signal amplitude of the complex signal after the pulse compression;

[0021] The signal amplitude of the complex signal after the pulse compression is screened according to the amplitude threshold to obtain a valid pulse signal.

[0022] Optionally, determining a theoretical backscatter coefficient of the active calibrator according to an antenna gain and an amplification gain of the active calibrator specifically includes:

[0023] Using the formula Determine the theoretical backscatter coefficient of the active calibrator; where σ ARC is the theoretical backscattering coefficient of the active calibrator; λ is the wavelength of the transmitted signal; G rARC is the gain of the active calibrator receiving antenna; G a G is the gain of the active scaler to amplify the received power; tARC is the gain of the active calibrator transmitting antenna.

[0024] Optionally, determining the actual backscatter coefficient of the active calibrator according to the scatterometer quality inspection data and calibration results within the external calibration working time range in combination with the antenna pattern of the scatterometer measured in a ground laboratory specifically includes:

[0025] Using the formula Determine the actual backscatter coefficient of the active calibrator; where RCS meas is the actual backscatter coefficient of the active calibrator; P s is the echo power; R is the slant distance from the calibrator to the scatterometer; L w is the system link insertion loss; L cal is the automatic attenuation value of the receiver in calibration mode; L sc is the automatic attenuation value of the receiver in echo mode; G r G is the antenna gain at the time of receiving the scatterometer echo; t P is the antenna gain at the time of scatterometer pulse emission; cal is the echo power in calibration mode; L f It is the loss value of the internal calibration unit in calibration mode.

[0026] Optionally, it also includes:

[0027] The scatterometer observation signal within a set time period, the elevation angle and azimuth angle of the satellite-ground connection, the theoretical backscatter coefficient of the active calibrator and the actual backscatter coefficient of the active calibrator are integrated into an external calibration synthesis file.

[0028] In a second aspect, the present application provides a scatterometer on-orbit satellite-ground integrated calibration system, the scatterometer on-orbit satellite-ground integrated calibration system is used to implement the above-mentioned scatterometer on-orbit satellite-ground integrated calibration method, the scatterometer on-orbit satellite-ground integrated calibration system includes:

[0029] A data acquisition module, used to acquire the downlink data of the scatterometer; the downlink data includes the scatterometer observation signal, observation time and scanning angle;

[0030] A data screening module, used for screening the scatterometer observation signal according to the weather forecast data to obtain the screened scatterometer observation signal; the weather forecast data includes water vapor, cloud cover and rainfall; the screened scatterometer observation signal is the scatterometer observation signal under clear sky conditions;

[0031] A quality inspection module is used to perform quality inspection on the downlink data of the scatterometer to obtain quality inspection data, and to segment the quality inspection data based on the external calibration working time range to extract the quality inspection data within the external calibration working time range;

[0032] A positioning module, used to determine the elevation angle and azimuth angle of the satellite-to-ground connection according to the quality inspection data within the working time range of the external calibration; the satellite-to-ground connection is the connection between the satellite and the ground calibration station coordinates;

[0033] An antenna pattern calculation module, used to determine the actual antenna pattern of the scatterometer according to the filtered scatterometer observation signal and the elevation angle and azimuth angle of the satellite-to-ground connection;

[0034] A comparison experiment data module is used to compare the actual antenna pattern with the antenna pattern of the scatterometer measured in the ground laboratory to determine a comparison result;

[0035] A calibration module, used for performing calibration according to the elevation angle and azimuth angle of the satellite-to-ground line and the scatterometer observation signal received by the ground calibration station to obtain a calibration result; the calibration result is the antenna gain of the scatterometer at the matching point; the matching point is a time matching point that satisfies the time difference threshold; the time matching point is obtained by matching the effective pulse signal with the elevation angle and azimuth angle of the satellite-to-ground line through time; the effective pulse signal is determined based on the scatterometer observation signal received by the ground calibration station;

[0036] An antenna pattern calculation module is used to interpolate the antenna gain of the scatterometer according to the filtered scatterometer observation signal and the elevation angle and azimuth angle of the satellite-to-ground connection to determine the actual antenna pattern of the scatterometer;

[0037] A comparison experiment data module is used to compare the actual antenna pattern with the antenna pattern of the scatterometer measured in the ground laboratory to determine a comparison result;

[0038] A data forwarding mode calibration module, used to determine the theoretical backscatter coefficient of the active calibrator according to the antenna gain and amplification gain of the active calibrator, and determine the actual backscatter coefficient of the active calibrator according to the scatterometer quality inspection data and calibration results within the external calibration working time range, combined with the antenna radiation pattern of the scatterometer measured by the ground laboratory; the antenna gain of the active calibrator is measured by the ground laboratory;

[0039] The calibration coefficient calculation module is used to determine the absolute calibration coefficient according to the theoretical backscatter coefficient of the active calibrator and the actual backscatter coefficient of the active calibrator to complete the calibration task; the calibration task includes determining the comparison result and the absolute calibration coefficient.

[0040] Optionally, it also includes:

[0041] The data integration module is used to integrate the scatterometer observation signal within a set period, the pitch angle and azimuth angle of the satellite-ground connection, the theoretical backscatter coefficient of the active calibrator and the actual backscatter coefficient of the active calibrator to obtain an external calibration synthesis file.

[0042] In a third aspect, the present application provides a computer device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement any of the above-described methods for in-orbit satellite-ground integrated calibration of a scatterometer.

[0043] In a fourth aspect, the present application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements any of the above-described methods for scatterometer on-orbit, satellite-ground integrated calibration.

[0044] In a fifth aspect, the present application provides a computer program product, including a computer program, which, when executed by a processor, implements any of the above-mentioned scatterometer on-orbit satellite-ground integrated calibration methods.

[0045] According to the specific embodiments provided in this application, this application discloses the following technical effects:

[0046] The present application provides a method, system, equipment, medium and product for on-orbit satellite-ground integrated calibration of a scatterometer, which screens the scatterometer observation signal according to meteorological forecast data, screens the scatterometer observation signal under clear sky conditions, performs quality inspection on the downlink data of the scatterometer, extracts the quality inspection data within the working time range of the external calibration, determines the elevation angle and azimuth of the satellite-ground connection according to the quality inspection data, calibrates the scatterometer antenna gain according to the elevation angle and azimuth of the satellite-ground connection and the scatterometer observation signal received by the ground calibration station, determines the actual antenna pattern of the scatterometer according to the scatterometer observation signal under clear sky conditions and the elevation angle and azimuth of the satellite-ground connection, and determines the comparison result with the antenna pattern measured in the ground laboratory before launch; determines the theoretical backscatter coefficient according to the antenna gain and amplification gain of the active calibrator, determines the actual backscatter coefficient according to the quality inspection data and the antenna gain of the scatterometer combined with the measured antenna pattern, and then determines the absolute calibration coefficient to complete the calibration task. The present application improves the calibration accuracy and inspection capability of the scatterometer. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0048] Figure 1 A schematic flow chart of an on-orbit satellite-ground integrated calibration method for a scatterometer provided in one embodiment of the present application;

[0049] Figure 2 A schematic diagram of the structure of a computer device provided in one embodiment of the present application. DETAILED DESCRIPTION

[0050] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0051] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0052] The external calibration proposed in this application adopts an active calibration method, using an active radar calibrator, which can process the original radar signal by time delay, frequency shift, etc. It has the advantages of compact structure, antenna beam width, large radar scattering cross section, stability, high precision, etc., and can be regarded as an effective calibration tool for scatterometers (i.e., the scatterometer-wind field measurement radar and similar remote sensing instruments carried by Fengyun-3E satellite (FY-3E)). The scatterometer transmits a pulse signal, and the active calibrator can work in the receiving mode to receive the signal sent by the scatterometer; after signal processing of the effective data, the scatterometer antenna pattern is fitted according to the active calibrator observation data at different times, different azimuths, and different elevation angles. The scatterometer transmits a pulse signal, and the active calibrator can also work in the forwarding mode to receive the signal sent by the scatterometer, which is forwarded after time shift / frequency shift and amplification and received by the scatterometer; the scatterometer absolute calibration coefficient is calculated according to the backscatter coefficient of the active calibrator and the backscatter coefficient calculated from the scatterometer observation data. The accurately determined absolute calibration coefficients and actual antenna patterns are further used for scatterometer data preprocessing to improve the scatterometer data processing accuracy.

[0053] This application develops a set of software and application platform for data processing of the on-orbit satellite-ground integrated calibration system of the scatterometer, successfully realizes daily scheduled scheduling, automatically obtains the actual antenna radiation pattern and absolute calibration coefficients, and displays them visually on the application platform.

[0054] In an exemplary embodiment, Figure 1 As shown, a scatterometer on-orbit satellite-ground integrated calibration method is provided, comprising the following steps:

[0055] S1: Acquire the downlink data of the scatterometer, which includes the scatterometer observation signal, observation time and scanning angle.

[0056] S2: According to the meteorological forecast data, the scatterometer observation signal is screened to obtain a screened scatterometer observation signal; the meteorological forecast data includes water vapor, cloud cover and rainfall; the screened scatterometer observation signal is a scatterometer observation signal under clear sky conditions.

[0057] In practical applications, after rolling acquisition of long-term field calibration experiment processing data (scatterometer observation signals), threshold screening is performed on the field calibration experiment processing data for a specified time period according to meteorological forecast data to select the scatterometer observation signals obtained under clear sky conditions.

[0058] S3: Performing quality inspection on the downlink data of the scatterometer to obtain scatterometer quality inspection data, and segmenting the scatterometer quality inspection data based on the external calibration working time range to extract the scatterometer quality inspection data within the external calibration working time range.

[0059] In practical applications, the downlink data of the scatterometer is unpacked according to the format, and the data quality is judged by satellite status, instrument status, time validity, temperature validity, etc. to obtain quality inspection data. Then, according to the external calibration working time range of the scatterometer provided by the field ground calibration station, the scatterometer quality inspection data is divided according to the external calibration working time range, and the scatterometer quality inspection data within the external calibration working time range is extracted.

[0060] S4: Determine the elevation angle and azimuth angle of the satellite-to-ground line according to the scatterometer quality inspection data within the external calibration working time range; the satellite-to-ground line is a line connecting the coordinates of the satellite and the ground calibration station.

[0061] In practical applications, the quality inspection data within the working time range of external calibration is positioned. The positioning is responsible for calculating the angle between the satellite and the ground calibration station coordinates through the satellite's GPS position and time, that is, the elevation angle and azimuth of the satellite-to-ground line, and writing the calculated elevation angle and azimuth of the satellite-to-ground line into the external calibration file to generate external calibration positioning data. The calculation method is as follows:

[0062] 1. Extract the scatterometer emission time from the quality inspection data within the external calibration working time range, extract the active calibrator azimuth, elevation angle and other pointing angle information from the active calibrator data file, as well as the active calibrator delay and other information. Determine whether the external calibration working mode is forwarding mode or receiving mode based on conditions such as receiver gain, or determine whether the external calibration working mode is forwarding mode or receiving mode based on the working mode symbol of the quality inspection data within the external calibration working time range.

[0063] 2. Processing by mode:

[0064] 2.1 If it is the forwarding mode: (a) Calculate the E-face angle and H-face angle of the scatterometer according to the scatterometer transmission time in the quality inspection file (including the quality inspection data within the working time range of the external calibration), calculate the distance from the scatterometer to the active calibrator through the longitude and latitude of the scatterometer and the longitude and latitude of the active calibrator, calculate the satellite speed according to the scatterometer transmission time, and then calculate the component of the satellite speed on the line from the scatterometer to the active calibrator to obtain the satellite speed component. (b) Calculate the receiving time of the active calibrator and calculate the E-face angle and H-face angle of the active calibrator. (c) Calculate the transmission time of the active calibrator and calculate the E-face angle and H-face angle of the active calibrator. (d) Calculate the receiving time of the scatterometer, calculate the E-face angle and H-face angle of the scatterometer, calculate the distance from the scatterometer to the active calibrator, and calculate the satellite speed component. The calculation method is the same as step (a).

[0065] Wherein, scatterometer transmission time = scatterometer pulse transmission time, which is obtained from the downlink data.

[0066] Active calibrator receiving time = scatterometer pulse emission time + slant range / c, where c is the speed of light.

[0067] 2.2 If it is receiving mode, (a) calculate the E-face angle and H-face angle of the scatterometer according to the scatterometer transmission time in the quality inspection file. (b) calculate the receiving time of the active calibrator and calculate the E-face angle and H-face angle of the active calibrator.

[0068] 1) Calculation of E-face angle and H-face angle of scatterometer:

[0069] Calculate the unitized direction U from the active calibrator to the scatterometer in the ECR coordinate system (earth centered rotational coordinate system) SG .

[0070] For 4 scatterometer panels V_Rad = (RT)*T_Roat*M_ECR2inst*U SG ;

[0071]

[0072] Where V_Rad is the observation vector in the scatterometer coordinate system; RT is the inverse matrix of the instrument installation matrix; T_Roat is the scatterometer rotation matrix; M_ECR2inst is the ECR to instrument coordinate system rotation matrix, and θ1 is the rotation angle in azimuth (radians).

[0073] Then the E-face angle and H-face angle of the scatterometer are calculated as:

[0074] E 角 =arctan(V_Rad_X / V_Rad_Z)*180 / π.

[0075] H 角 =arctan(V_Rad_Y / V_Rad_Z)*180 / π.

[0076] 2) Calculation of E-face angle and H-face angle of active calibrator:

[0077] Calculate the unitized direction (ECR) U from the scatterometer to the active calibrator in the ECR coordinate system GS , and U GS Convert to the ground calibration station (RD) coordinate system.

[0078] V_Sta=T_ECR2Sta*U GS .

[0079] Among them, V_Sta is the observation vector in the ground calibration station coordinate system; T_ECR2Sta is the conversion matrix from the ECR coordinate system to the ground calibration station coordinate system, which is obtained by calculating the vector according to the latitude and longitude of the ground calibration station. The calculation method is as follows:

[0080] According to the station coordinates of the ground calibration station (RaLat_RD, RaLon_RD, H_RD), RaLat_RD is the latitude of the ground calibration station; RaLon_RD is the longitude of the ground calibration station; H_RD is the elevation of the ground calibration station, first calculate the normal vector North_RD is the north direction vector; calculate TEast_RD = North_RD × Norm_RD, TEast_RD is the intermediate transition parameter; normalize the vector TEast_RD to UE = TEast_RD / |TEast_RD|, calculate TN = Norm_RD × UE, TN is the intermediate transition parameter; normalize the vector TN to UN = TN / |TN|, and finally

[0081] Then calculate the coordinates of the vector from the active calibrator to the satellite on the ground to rotate the calibrator V_RD = T_Sta2RD * V_Sta, and the rotation matrix T_Sta2RD is:

[0082]

[0083] Among them, θ1, They are the elevation angle and azimuth angle of the calibrator antenna coordinate system relative to the geographic coordinate system.

[0084] The E-face angle and H-face angle of the active scaler are:

[0085] E 角 =arctan(V_RD_X / V_RD_Z)*180 / π.

[0086] H 角 =arctan(V_RD_Y / V_RD_Z)*180 / π.

[0087] S5: Calibrate according to the elevation angle and azimuth angle of the satellite-to-ground line and the scatterometer observation signal received by the ground calibration station to obtain a calibration result; the calibration result is the antenna gain of the scatterometer at the matching point; the matching point is a time matching point that meets the time difference threshold; the time matching point is obtained by matching the effective pulse signal with the elevation angle and azimuth angle of the satellite-to-ground line through time; the effective pulse signal is determined based on the scatterometer observation signal received by the ground calibration station.

[0088] As an optional implementation manner, determining a valid pulse signal based on a scatterometer observation signal received by a ground calibration station specifically includes:

[0089] The scatterometer observation signal received by the ground calibration station is down-converted to obtain a baseband signal.

[0090] Perform matched filtering on the baseband signal to obtain a matched filtered signal.

[0091] The matched filtered signal is pulse compressed using a matching function to obtain a pulse compressed complex signal.

[0092] The signal amplitude of the complex signal after the pulse compression is determined.

[0093] The signal amplitude of the complex signal after the pulse compression is screened according to the amplitude threshold to obtain a valid pulse signal.

[0094] In practical applications, the external calibration quality inspection data and the scatterometer observation signal received by the ground calibration station are calibrated, and the calibration result is the antenna gain of the scatterometer at the matching point.

[0095] For the scatterometer observation signal received by the ground calibration station, it is first necessary to down-convert it into a baseband signal, and then obtain the signal after matched filtering through data processing such as matched filtering. Construct a matching function for pulse compression, and calculate the signal amplitude of the complex signal after pulse compression. According to the set threshold, that is, the amplitude threshold, extract the effective pulse signal. The extracted effective pulse signal is matched with the elevation angle and azimuth angle of the satellite-to-ground line through time (or Fourier transform the scatterometer observation signal received by the ground calibration station, take out the local extreme signal point that meets a certain signal-to-noise ratio, and match it with the elevation angle and azimuth angle of the satellite-to-ground line through time), obtain the time matching point where the time difference meets the threshold condition, calculate the antenna gain corresponding to the matching point, and write the calibration result into the external calibration file.

[0096] S6: interpolating the antenna gain of the scatterometer according to the filtered scatterometer observation signal and the elevation angle and azimuth angle of the satellite-to-ground line to determine the actual antenna pattern of the scatterometer.

[0097] In practical applications, the antenna gain of the scatterometer is interpolated in three dimensions according to the elevation angle and azimuth angle of the corresponding satellite-ground line using the filtered scatterometer observation signal, and the actual antenna radiation pattern of the scatterometer is plotted.

[0098] S7: Compare the actual antenna pattern with the antenna pattern of the scatterometer measured in the ground laboratory to determine a comparison result.

[0099] In practical applications, the actual antenna pattern obtained by the above calculation is compared with the antenna pattern of the scatterometer measured in the ground laboratory and the comparison result is obtained to complete one of the two major tasks of external calibration.

[0100] S8: Determine the theoretical backscatter coefficient of the active calibrator according to the antenna gain and amplification gain of the active calibrator, and determine the actual backscatter coefficient of the active calibrator according to the quality inspection data and calibration results within the working time range of the external calibration in combination with the antenna radiation pattern of the scatterometer measured in the ground laboratory.

[0101] In practical applications, extracting points near the maximum value of a single transit data is the sampling point of a single distance section during a single transit, and extracting all sampling points covered by a single beam can obtain the azimuth corresponding pattern section. After obtaining the pattern data under multiple different observation geometries, the three-dimensional antenna pattern is obtained by fitting, which is the antenna pattern of the scatterometer measured in the ground laboratory.

[0102] As an optional implementation manner, determining the theoretical backscatter coefficient of the active calibrator according to the antenna gain and the amplification gain of the active calibrator specifically includes:

[0103] Using the formula Determine the theoretical backscatter coefficient of the active calibrator; where σ ARC is the theoretical backscattering coefficient of the active calibrator; λ is the wavelength of the transmitted signal; G rARC is the gain of the active calibrator receiving antenna; G a G is the gain of the active scaler to amplify the received power; tARC is the gain of the active calibrator transmitting antenna.

[0104] In practical applications, the theoretical backscatter coefficient of the active calibrator is calculated for all valid observation data of the satellite flying over the active calibrator (the scatterometer observation signal received by the ground calibration station).

[0105] The transmission power received by the active calibrator from the scatterometer is:

[0106]

[0107] Among them, P ARC is the power received by the active calibrator, P t is the scatterometer transmission power, G t is the gain of the scatterometer transmitting antenna, G rARC is the gain of the active calibrator receiving antenna, λ is the wavelength of the transmitted signal, and R is the distance between the active calibrator and the scatterometer.

[0108] After the active calibrator receives the transmission power from the scatterometer, it is amplified and then transmitted by the transmitting antenna of the active calibrator. The power received by the scatterometer is:

[0109]

[0110] G a is the gain of the active scaler to amplify the received power, G tARC is the transmit antenna gain of the active calibrator.

[0111] Then the backscattering cross-sectional area of ​​the active calibrator is:

[0112]

[0113] This is the theoretical backscattering coefficient of the active calibrator, denoted as σ_theo.

[0114] As an optional implementation manner, determining the actual backscatter coefficient of the active calibrator according to the scatterometer quality inspection data within the external calibration working time range in combination with the antenna pattern of the scatterometer measured in the ground laboratory specifically includes:

[0115] Using the formula Determine the actual backscatter coefficient of the active calibrator; where RCS measis the actual backscatter coefficient of the active calibrator; P s is the echo power; R is the slant distance from the calibrator to the scatterometer; L w is the system link insertion loss; L cal L is the automatic attenuation value of the receiver in calibration mode; sc is the automatic attenuation value of the receiver in echo mode; G r G is the antenna gain at the time of receiving the scatterometer echo; t P is the antenna gain at the time of scatterometer pulse emission; cal is the echo power in calibration mode; L f It is the loss value of the internal calibration unit in calibration mode.

[0116] In practical applications, the actual backscatter coefficient of the active calibrator observed by the scatterometer is calculated.

[0117] Read the scatterometer observation data after quality inspection in the external calibration mode of the scatterometer (i.e., the quality inspection data within the working time range of the external calibration), and calculate the actual backscatter coefficient of the active calibrator observed by the scatterometer; obtain the G at the time of pulse transmission from the antenna pattern of the scatterometer measured by the ground laboratory t and G at the time of echo reception r ; Separate the H polarization data and V polarization data, and calculate the actual backscatter coefficient RCS of the active calibrator meas , recorded as σ_meas. According to the emission time of the three designs in the quality inspection data within the working time range of the external calibration, the H polarization data and the V polarization data are determined. After separating the H and V polarization data, the actual backscattering coefficients of the two polarizations are calculated respectively.

[0118] Write the theoretical backscatter coefficient and actual backscatter coefficient of the active calibrator into the external calibration file.

[0119] S9: Determine an absolute calibration coefficient according to the theoretical backscatter coefficient of the active calibrator and the actual backscatter coefficient of the active calibrator to complete a calibration task; the calibration task includes determining the comparison result and the absolute calibration coefficient.

[0120] In practical applications, the theoretical backscatter coefficient of the active calibrator is calculated and compared with the actual backscatter coefficient of the active calibrator observed by the scatterometer, and the difference is made and plotted to obtain the absolute calibration coefficient of the scatterometer, thus completing the second task of external calibration.

[0121] This application uses the field calibration data of the wind field measurement radar carried by FY-3E. Based on the above technical solution, the software and application platform for data processing of the on-orbit integrated satellite-ground calibration system of the wind field measurement radar are developed. It successfully realizes on-demand scheduled scheduling, automatically obtains antenna radiation patterns and calibration coefficients, and displays them visually on the application platform.

[0122] In an exemplary embodiment, a scatterometer on-orbit satellite-ground integrated calibration system is provided, and the scatterometer on-orbit satellite-ground integrated calibration system is used to implement the above-mentioned scatterometer on-orbit satellite-ground integrated calibration method, and the scatterometer on-orbit satellite-ground integrated calibration system includes:

[0123] The data acquisition module is used to acquire the downlink data of the scatterometer; the downlink data includes the scatterometer observation signal, observation time and scanning angle.

[0124] The data screening module is used to screen the scatterometer observation signal according to the meteorological forecast data to obtain the screened scatterometer observation signal; the meteorological forecast data includes water vapor, cloud cover and rainfall; the screened scatterometer observation signal is the scatterometer observation signal under clear sky conditions.

[0125] The quality inspection module is used to perform quality inspection on the downlink data of the scatterometer to obtain the scatterometer quality inspection data, and to segment the scatterometer quality inspection data based on the external calibration working time range to extract the scatterometer quality inspection data within the external calibration working time range.

[0126] The positioning module is used to determine the pitch angle and azimuth angle of the satellite-to-ground line according to the scatterometer quality inspection data within the external calibration working time range; the satellite-to-ground line is the coordinate line between the satellite and the ground calibration station.

[0127] A calibration module is used to perform calibration according to the elevation angle and azimuth angle of the satellite-to-ground line and the scatterometer observation signal received by the ground calibration station to obtain a calibration result; the calibration result is the antenna gain of the scatterometer at the matching point; the matching point is a time matching point that meets the time difference threshold; the time matching point is obtained by matching the effective pulse signal with the elevation angle and azimuth angle of the satellite-to-ground line through time; the effective pulse signal is determined based on the scatterometer observation signal received by the ground calibration station.

[0128] The antenna pattern calculation module is used to interpolate the antenna gain of the scatterometer according to the filtered scatterometer observation signal and the elevation angle and azimuth angle of the satellite-to-ground line to determine the actual antenna pattern of the scatterometer.

[0129] The comparison experiment data module is used to compare the actual antenna pattern with the antenna pattern of the scatterometer measured in the ground laboratory to determine the comparison result.

[0130] The data forwarding mode calibration module is used to determine the theoretical backscatter coefficient of the active calibrator according to the antenna gain and amplification gain of the active calibrator, and to determine the actual backscatter coefficient of the active calibrator according to the scatterometer quality inspection data and calibration results within the external calibration working time range, combined with the antenna radiation pattern of the scatterometer measured in the ground laboratory; the antenna gain of the active calibrator is measured in the ground laboratory.

[0131] The calibration coefficient calculation module is used to determine the absolute calibration coefficient according to the theoretical backscatter coefficient of the active calibrator and the actual backscatter coefficient of the active calibrator to complete the calibration task; the calibration task includes determining the comparison diagram and the absolute calibration coefficient.

[0132] As an optional implementation, it also includes:

[0133] The data integration module is used to integrate the scatterometer observation signal within a set period, the pitch angle and azimuth angle of the satellite-ground connection, the theoretical backscatter coefficient of the active calibrator and the actual backscatter coefficient of the active calibrator to obtain an external calibration synthesis file.

[0134] In an exemplary embodiment, a computer device is provided. The computer device may be a server or a terminal. The internal structure diagram thereof may be as follows: Figure 2 As shown. The computer device includes a processor, a memory, an input / output interface (Input / Output, referred to as I / O) and a communication interface. The processor, the memory and the input / output interface are connected through a system bus, and the communication interface is connected to the system bus through the input / output interface. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The input / output interface of the computer device is used to exchange information between the processor and an external device. The communication interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, a scatterometer on-orbit satellite-ground integrated calibration method is implemented.

[0135] Those skilled in the art will understand that Figure 2The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components. In an exemplary embodiment, a computer device is provided, including a memory and a processor, wherein a computer program is stored in the memory, and when the processor executes the computer program, the above-mentioned scatterometer on-orbit satellite-ground integrated calibration method is implemented.

[0136] In an exemplary embodiment, a computer-readable storage medium is provided, storing a computer program, which, when executed by a processor, implements the above-mentioned scatterometer on-orbit satellite-ground integrated calibration method.

[0137] In an exemplary embodiment, a computer program product is provided, including a computer program, which, when executed by a processor, implements the above-mentioned scatterometer on-orbit satellite-ground integrated calibration method.

[0138] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of relevant data must comply with relevant regulations.

[0139] Those of ordinary skill in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to the memory, database or other medium used in the embodiments provided in the present application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM may be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).

[0140] The database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database. The non-relational database may include a distributed database based on blockchain, etc., but is not limited thereto. The processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, etc., but is not limited thereto.

[0141] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0142] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A scatterometer on-orbit satellite-ground integrated calibration method, characterized in that: include: Obtain the downlink data from the scatterometer; The downlinked data includes the scatterometer observation signal, observation time and scanning angle; According to the weather forecast data, the scatterometer observation signal is screened to obtain a screened scatterometer observation signal; the weather forecast data includes water vapor, cloud cover and rainfall; the screened scatterometer observation signal is a scatterometer observation signal under clear sky conditions; Performing quality inspection on the downlink data of the scatterometer to obtain scatterometer quality inspection data, and segmenting the scatterometer quality inspection data based on the external calibration working time range to extract the scatterometer quality inspection data within the external calibration working time range; Determine the elevation angle and azimuth angle of the satellite-to-ground line according to the scatterometer quality inspection data within the external calibration working time range; the satellite-to-ground line is a line connecting the coordinates of the satellite and the ground calibration station; Calibration is performed according to the elevation angle and azimuth angle of the satellite-to-ground line and the scatterometer observation signal received by the ground calibration station to obtain a calibration result; the calibration result is the antenna gain of the scatterometer at the matching point; the matching point is a time matching point that meets the time difference threshold; the time matching point is obtained by matching the effective pulse signal with the elevation angle and azimuth angle of the satellite-to-ground line through time; the effective pulse signal is determined based on the scatterometer observation signal received by the ground calibration station; Interpolating the antenna gain of the scatterometer according to the filtered scatterometer observation signal and the elevation angle and azimuth angle of the satellite-to-ground line to determine the actual antenna pattern of the scatterometer; Comparing the actual antenna pattern with the antenna pattern of the scatterometer measured in the ground laboratory before launching, and determining a comparison result; Determine the theoretical backscatter coefficient of the active calibrator according to the antenna gain and amplification gain of the active calibrator, and determine the actual backscatter coefficient of the active calibrator according to the scatterometer quality inspection data and calibration results within the working time range of the external calibration, combined with the antenna radiation pattern of the scatterometer measured in the ground laboratory; the antenna gain of the active calibrator is measured in the ground laboratory; According to the theoretical backscatter coefficient of the active calibrator and the actual backscatter coefficient of the active calibrator, an absolute calibration coefficient is determined to complete a calibration task; the calibration task includes determining the comparison result and the absolute calibration coefficient.

2. The on-orbit satellite-ground integrated calibration method for a scatterometer according to claim 1, characterized in that: Determine the effective pulse signal based on the scatterometer observation signal received by the ground calibration station, specifically including: Down-convert the scatterometer observation signal received by the ground calibration station to obtain a baseband signal; Performing matched filtering on the baseband signal to obtain a matched filtered signal; Performing pulse compression on the matched filtered signal using a matching function to obtain a pulse compressed complex signal; Determining the signal amplitude of the complex signal after the pulse compression; The signal amplitude of the complex signal after the pulse compression is screened according to the amplitude threshold to obtain a valid pulse signal.

3. The on-orbit satellite-ground integrated calibration method for a scatterometer according to claim 1, characterized in that: According to the antenna gain and amplification gain of the active calibrator, the theoretical backscatter coefficient of the active calibrator is determined, including: Using the formula Determine the theoretical backscatter coefficient of the active calibrator; where σ ARC is the theoretical backscattering coefficient of the active calibrator; λ is the wavelength of the transmitted signal; G rARC is the gain of the active calibrator receiving antenna; G a G is the gain of the active scaler to amplify the received power; tARC is the gain of the active calibrator transmitting antenna.

4. The on-orbit satellite-ground integrated calibration method for a scatterometer according to claim 1, characterized in that: According to the scatterometer quality inspection data and calibration results within the external calibration working time range, combined with the antenna pattern of the scatterometer measured in the ground laboratory, the actual backscatter coefficient of the active calibrator is determined, specifically including: Using the formula Determine the actual backscatter coefficient of the active calibrator; where RCS meas is the actual backscatter coefficient of the active calibrator; P s is the echo power; R is the slant distance from the calibrator to the scatterometer; L w is the system link insertion loss; L cal is the automatic attenuation value of the receiver in calibration mode; L sc is the automatic attenuation value of the receiver in echo mode; G r G is the antenna gain at the time of receiving the scatterometer echo; t P is the antenna gain at the time of scatterometer pulse emission; cal is the echo power in calibration mode; L f It is the loss value of the internal calibration unit in calibration mode.

5. The on-orbit satellite-ground integrated calibration method for a scatterometer according to claim 1, characterized in that: Also includes: The scatterometer observation signal within a set time period, the elevation angle and azimuth angle of the satellite-ground connection, the theoretical backscatter coefficient of the active calibrator and the actual backscatter coefficient of the active calibrator are integrated into an external calibration synthesis file.

6. A scatterometer on-orbit satellite-ground integrated calibration system, characterized in that: The scatterometer on-orbit satellite-ground integrated calibration system is used to implement the scatterometer on-orbit satellite-ground integrated calibration method according to claims 1-5, and the scatterometer on-orbit satellite-ground integrated calibration system comprises: A data acquisition module, used to acquire the downlink data of the scatterometer; the downlink data includes the scatterometer observation signal, observation time and scanning angle; A data screening module is used to screen the scatterometer observation signal according to the weather forecast data to obtain the screened scatterometer observation signal; the weather forecast data includes water vapor, cloud cover and rainfall; the screened scatterometer observation signal is the scatterometer observation signal under clear sky conditions; A quality inspection module is used to perform quality inspection on the downlink data of the scatterometer to obtain the scatterometer quality inspection data, and to segment the scatterometer quality inspection data based on the external calibration working time range to extract the scatterometer quality inspection data within the external calibration working time range; A positioning module, used to determine the elevation angle and azimuth angle of the satellite-to-ground line according to the scatterometer quality inspection data within the external calibration working time range; the satellite-to-ground line is a line connecting the coordinates of the satellite and the ground calibration station; A calibration module, used for performing calibration according to the elevation angle and azimuth angle of the satellite-to-ground line and the scatterometer observation signal received by the ground calibration station to obtain a calibration result; the calibration result is the antenna gain of the scatterometer at the matching point; the matching point is a time matching point that satisfies the time difference threshold; the time matching point is obtained by matching the effective pulse signal with the elevation angle and azimuth angle of the satellite-to-ground line through time; the effective pulse signal is determined based on the scatterometer observation signal received by the ground calibration station; An antenna pattern calculation module is used to interpolate the antenna gain of the scatterometer according to the filtered scatterometer observation signal and the elevation angle and azimuth angle of the satellite-to-ground connection to determine the actual antenna pattern of the scatterometer; A comparison experiment data module is used to compare the actual antenna pattern with the antenna pattern of the scatterometer measured in the ground laboratory before launch to determine the comparison result; A data forwarding mode calibration module, used to determine the theoretical backscatter coefficient of the active calibrator according to the antenna gain and amplification gain of the active calibrator, and determine the actual backscatter coefficient of the active calibrator according to the scatterometer quality inspection data and calibration results within the external calibration working time range, combined with the antenna radiation pattern of the scatterometer measured by the ground laboratory; the antenna gain of the active calibrator is measured by the ground laboratory; The calibration coefficient calculation module is used to determine the absolute calibration coefficient according to the theoretical backscatter coefficient of the active calibrator and the actual backscatter coefficient of the active calibrator to complete the calibration task; the calibration task includes determining the comparison result and the absolute calibration coefficient.

7. The on-orbit satellite-ground integrated calibration system for scatterometers according to claim 6, characterized in that: Also includes: The data integration module is used to integrate the scatterometer observation signal within a set period, the pitch angle and azimuth angle of the satellite-ground connection, the theoretical backscatter coefficient of the active calibrator and the actual backscatter coefficient of the active calibrator to obtain an external calibration synthesis file.

8. A computer device comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the on-orbit satellite-ground integrated calibration method for a scatterometer according to any one of claims 1 to 5.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the on-orbit satellite-ground integrated calibration method for a scatterometer according to any one of claims 1 to 5 is implemented.

10. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the on-orbit satellite-ground integrated calibration method for a scatterometer according to any one of claims 1 to 5 is implemented.

Images