Doppler radar speed measurement accuracy calibration method and device

Abstract

The present invention relates to a Doppler radar velocity measurement accuracy calibration method, comprising: preprocessing collected Doppler frequency data and navigation satellite data; performing velocity calculation based on the Doppler frequency to obtain first velocity data; calculating velocity data based on the navigation satellite data, and obtaining second velocity data based on a carrier coordinate system through coordinate conversion; interpolating and fusing the first velocity data and the second velocity data point by point using the same time base; calculating the three-axis velocity difference and scale factor difference of each data point in the fused data; and calibrating the three-axis velocity error, scale factor error stability, and random noise of the Doppler radar based on the three-axis velocity difference and scale factor difference. The present invention is applicable to the analysis of radar velocity measurement accuracy of aircraft in any terrain, flight path, and time, achieving a comprehensive assessment of the Doppler radar and contributing to the continuous improvement of the Doppler radar.

Description

Technical Field

[0001] The present invention relates to the technical field of Doppler radar, and in particular to a Doppler radar speed measurement accuracy calibration method and device. Background Art

[0002] Doppler radar uses the Doppler effect to measure speed, obtaining velocity information by measuring the frequency difference between the electromagnetic waves emitted by the radar and the echo. The purpose of Doppler radar is to enhance the autonomous capabilities of aircraft and improve their survival rate.

[0003] The three-axis velocity values ​​of Doppler radar determine the accuracy of aircraft speed and positioning, which is the main characteristic of Doppler radar. The speed measurement accuracy of aircraft is usually assessed by the speed measurement error of the three-axis velocity.

[0004] Traditional Doppler radar accuracy calibration often involves having an aircraft fly in a straight horizontal line at a certain altitude at a constant speed, and calculating the speed value using the distance and time between two points to complete comparative analysis.

[0005] Although this method is relatively simple, it has high requirements for the track and requires the aircraft to remain at a constant altitude and fly horizontally. It is not suitable for precision statistics in various flight conditions. In addition, the statistical accuracy is coarse, the indicators are not comprehensive enough, and the physical quantities such as distance and time used are not accurate enough. It can only roughly calculate the forward velocity error accuracy of the radar, and cannot calculate the lateral velocity error and vertical velocity error. It is even more unable to meet the analysis of items such as the Doppler radar's scale coefficient error stability and random noise. Summary of the Invention

[0006] In view of the above analysis, the present invention aims to provide a Doppler radar speed measurement accuracy calibration method and device to solve the problems of high track requirements, rough statistical accuracy and insufficient comprehensive indicators in the Doppler radar speed measurement accuracy analysis method.

[0007] The technical solution provided by the present invention is:

[0008] The present invention discloses a Doppler radar speed measurement accuracy calibration method, comprising the following steps:

[0009] Preprocessing the collected Doppler frequency data and navigation satellite data;

[0010] Performing velocity measurement calculation according to the pre-processed Doppler frequency to obtain first velocity measurement data based on the carrier coordinate system;

[0011] Calculating velocity data based on a celestial coordinate system according to the preprocessed navigation satellite data, and obtaining second velocity measurement data based on a carrier coordinate system through coordinate conversion;

[0012] Using the same time base, interpolating and fusing the first speed measurement data and the second speed measurement data point by point to obtain fused data;

[0013] Calculate the three-axis velocity difference and scale factor difference of each data point in the fused data;

[0014] According to the three-axis velocity difference and the scale coefficient difference, the three-axis velocity error, the scale coefficient error stability and the random noise of the Doppler radar are calibrated.

[0015] Furthermore, the Doppler radar includes four radar beams in a centrally symmetrical X shape; the Doppler frequency data includes the Doppler frequency f collected by the first radar beam d1 , the Doppler frequency f collected by the second radar beam d2 , the Doppler frequency f collected by the third radar beam d3 and the Doppler frequency f collected by the fourth radar beam d4 ;

[0016] The first speed measurement data includes:

[0017]

[0018] Where, are the velocity components of the carrier coordinate system X, Y, and Z axes measured by the Doppler radar; γ0 is the angle between the beam centerline and the X axis of the carrier coordinate system; δ0 is the angle between the projection of the beam line on the corresponding plane and the Y axis of the carrier coordinate system; λ is the wavelength of the radar transmission signal.

[0019] Furthermore, the second velocity measurement data is obtained by converting the east, north, and sky axes velocities in the celestial coordinate system calculated based on the navigation satellite data into the X, Y, and Z axes velocities in the carrier coordinate system using the pitch angle, roll angle, and heading angle of the carrier; wherein the conversion formula is:

[0020]

[0021] Where γ, θ, and ψ are the roll angle, pitch angle, and heading angle of the carrier; are the velocity components of the east, north and celestial axes in the celestial coordinate system; are the three-axis velocity components in the carrier coordinate system.

[0022] Furthermore, the calibration of the three-axis velocity error includes:

[0023] 1) Determine whether the speed difference in each axis is greater than a preset speed difference threshold;

[0024] 2) If the error is greater than the threshold, the root mean square of the scale coefficient difference in the axis is used as the velocity error in the axis for calibration;

[0025] 3) If the value is less than the threshold, the standard deviation of the velocity difference in the axis is used as the velocity error in the axis for calibration.

[0026] Furthermore, the calibration coefficient error stability is calibrated as the standard deviation of the calibration coefficient difference.

[0027] Furthermore, the axial random noise is calibrated as the root mean square of the axial velocity differences.

[0028] Furthermore, the Doppler radar calibration coefficient difference Where, δV i D is the velocity difference of the three axes; V i G The three-axis velocity of the second velocity measurement data, i=X, Y, Z.

[0029] The present invention also discloses a Doppler radar speed measurement accuracy calibration device, comprising:

[0030] A preprocessing module, used for preprocessing the collected Doppler frequency data and navigation satellite data;

[0031] A first speed measurement data calculation module is used to perform speed measurement calculation according to the preprocessed Doppler frequency to obtain first speed measurement data based on the carrier coordinate system;

[0032] A second speed measurement data calculation module is used to calculate speed data based on a celestial coordinate system according to the preprocessed navigation satellite data, and obtain second speed measurement data based on a carrier coordinate system through coordinate conversion;

[0033] An interpolation and fusion module is used to interpolate and fuse the first speed measurement data and the second speed measurement data point by point using the same time base;

[0034] The difference calculation module is used to calculate the three-axis velocity difference and scale coefficient difference of each data point of the fused data;

[0035] The parameter calibration module is used to calculate the three-axis velocity error, the scale coefficient error stability and the random noise according to the three-axis velocity difference and the scale coefficient difference, so as to calibrate the speed measurement accuracy of the Doppler radar.

[0036] Furthermore, the parameter calibration module includes a first calibration module, a second calibration module and a third calibration module;

[0037] The first calibration module is used to calibrate the three-axis velocity error parameters of Doppler radar velocity measurement;

[0038] The second calibration module is used to calibrate the scale coefficient error stability parameter of the Doppler radar speed measurement;

[0039] The third calibration module is used to calibrate the random noise parameters of Doppler radar speed measurement.

[0040] Furthermore, the calibration of the three-axis velocity error parameters by the first calibration module includes:

[0041] 1) Determine whether the speed difference in each axis is greater than a preset speed difference threshold;

[0042] 2) If the error is greater than the threshold, the root mean square of the scale coefficient difference in the axis is used as the velocity error in the axis for calibration;

[0043] 3) If the value is less than the threshold, the standard deviation of the velocity difference in the axis is used as the velocity error in the axis for calibration.

[0044] The present invention can achieve at least one of the following beneficial effects:

[0045] The Doppler radar velocity measurement accuracy calibration method and device disclosed in the present invention are applicable to the analysis of the Doppler radar velocity measurement accuracy of an aircraft under any terrain, any flight track, and any time segment. The method and device realize the calibration of the Doppler radar's three-axis velocity error, scale coefficient error stability, and random noise, comprehensively evaluate the Doppler radar, and contribute to the continuous improvement of the Doppler radar. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The accompanying drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like parts throughout the drawings.

[0047] Figure 1 This is a flow chart of the Doppler radar speed measurement accuracy calculation method of this embodiment;

[0048] Figure 2 A schematic diagram of the antenna beam configuration of this embodiment;

[0049] Figure 3 Schematic diagram of a top view of the integrated transceiver quad-beam antenna in this embodiment;

[0050] Figure 4 This is a principle block diagram of the Doppler radar velocity measurement accuracy calculation device of this embodiment. DETAILED DESCRIPTION

[0051] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, which constitute a part of this application and are used to illustrate the principles of the present invention together with the embodiments of the present invention.

[0052] This embodiment discloses a method for calculating the Doppler radar speed measurement accuracy. Figure 1 As shown, the following steps are included:

[0053] Step S1, preprocessing the collected Doppler frequency data and navigation satellite data;

[0054] Step S2: performing velocity measurement calculation according to the pre-processed Doppler frequency to obtain first velocity measurement data based on the carrier coordinate system;

[0055] Step S3: calculating velocity data based on the celestial coordinate system according to the pre-processed navigation satellite data, and obtaining second velocity measurement data based on the carrier coordinate system through coordinate conversion;

[0056] Step S4: Using the same time base, interpolate and fuse the first speed measurement data and the second speed measurement data point by point to obtain fused data;

[0057] Step S5, calculating the three-axis velocity difference and scale factor difference of each data point in the fused data;

[0058] Step S6: Calibrate the three-axis velocity error, scale factor error stability and random noise of the Doppler radar according to the three-axis velocity difference and the scale factor difference.

[0059] Specifically, the preprocessing of the collected Doppler frequency data and navigation satellite data in step S1 includes:

[0060] The Doppler radar data is removed from the Doppler radar data that exceeds the working range (speed measurement range, working altitude, working attitude) or is invalid. The navigation satellite data only retains the data during the test period.

[0061] For the aircraft's built-in navigation satellite positioning device (GPS / Beidou / or other satellite positioning systems), extract the aircraft system time, Doppler frequency data, and the three-axis velocity information of the aircraft's celestial coordinate system output by the satellite positioning device; the aircraft's attitude angle information (pitch angle, roll angle, heading angle) can be obtained by the inertial positioning device on board the aircraft or based on the satellite positioning device.

[0062] If the aircraft does not have a positioning device, the navigation satellite data can be obtained through a handheld navigation satellite positioning device carried on the aircraft, such as a handheld GPS / Beidou or differential GPS / Beidou terminal, to extract the aircraft's Beijing time, Doppler frequency data, satellite UTC time, and the three-axis velocity information of the celestial coordinate system positioned by the handheld navigation satellite positioning device. The attitude angle information (pitch angle, roll angle, heading angle) can be obtained by the inertial positioning device carried on the aircraft.

[0063] More specifically, the Doppler radar antenna of this embodiment adopts a symmetrical system with four radar beams arranged in a centrally symmetrical X shape, radiating electromagnetic wave beams in four different directions in turn. The specific working diagram is shown in FIG. Figure 2As shown, 1-4 in the figure represent four X-shaped radar beams that are centrally symmetrical.

[0064] Figure 2 The coordinate system shown in is the carrier coordinate system, the γ0 angle is the fixed angle between the antenna beam and the longitudinal axis of the aircraft, and the δ0 angle is the angle between the antenna beam and the longitudinal axis of the aircraft. y OV z Projection on the surface and V y The fixed angle between the two axes, β is the angle between the center line of the radar beam and the ground projection, v c is the pitch angle of the vehicle, γ c is the rolling angle of the vehicle, β′1, β′2, β′3, and β′4 are the angles between the center lines of beams 1 to 4 and their projections on the ground, respectively; γ is the angle between the center line of the entire beam and the X-axis of the vehicle's coordinate system; α is the angle between the projection of the center line of the entire beam on the plane where the center lines of beams 1 and 2 are located and the X-axis, is the angle between the beam centerline and the Z axis.

[0065] The Doppler frequency data includes the Doppler frequency f collected by the first radar beam d1 , the Doppler frequency f collected by the second radar beam d2 , the Doppler frequency f collected by the third radar beam d3 and the Doppler frequency f collected by the fourth radar beam d4 ;

[0066] According to the Doppler effect:

[0067]

[0068] Since the system only detects positive frequencies, and the forward speed is much greater than the lateral and vertical speeds, that is, V X D >>V Z D ,V Y D The above formula can be changed to:

[0069]

[0070] Then calculate V x , V y , V z The expression is as follows:

[0071] The three-axis speed in the carrier coordinate system included in the first speed measurement data is:

[0072]

[0073] Where, are the velocity components of the carrier coordinate system X, Y, and Z axes measured by the Doppler radar; γ0 is the angle between the beam centerline and the X axis of the carrier coordinate system; δ0 is the angle between the projection of the beam line on the corresponding plane and the Y axis of the carrier coordinate system; λ is the wavelength of the radar transmission signal.

[0074] To ensure that the Doppler radar antenna can generate four centrally symmetrical X-shaped radar waves, the Doppler radar antenna in this embodiment adopts a four-beam traveling waveguide antenna with a co-aperture integrated design of the transmit and receive antennas.

[0075] The transmitting antenna and receiving antenna of the four-beam traveling wave waveguide antenna both have four beams with strictly symmetrical beam pointing angles, ensuring that the precise flight speed of the flying vehicle in three directions can be calculated through the relationship between Doppler frequency shift and beam pointing angle.

[0076] Specifically, the staggered arrangement of the transmitting and receiving waveguides and their high and low placement solves the problem of antenna transmission and reception integration;

[0077] Because the receiving or transmitting antennas utilize traveling wave arrays with narrow waveguide slots, there is a large gap between the transmitting antenna's radiating waveguides to accommodate the receiving antenna's radiating waveguide. This allows for an integrated design of the radiating elements of the transmitting and receiving antennas by staggering the radiating waveguides of the transmitting and receiving antennas. Furthermore, considering the impact of the feed network, the radiating waveguides of the transmitting and receiving antennas are arranged at different heights within the same plane, allowing each feed waveguide to feed the transmitting and receiving antennas independently. This staggered arrangement and high-low placement of the radiating waveguides of the transmitting and receiving antennas achieves the miniaturization and integration of the transmitting and receiving antennas, ensuring that their beam pointing angles are aligned within a common reference coordinate system while also resolving the issue of staggered feeding of the transmitting and receiving antennas.

[0078] More specifically, Figure 3 As shown, the four-beam traveling waveguide antenna consists of several radiating waveguides and four feeding waveguides, and each radiating waveguide is a narrow-side slotted waveguide with the same structure.

[0079] The two upper feed waveguides are responsible for the transmitting antenna, with a total of four ports, generating four beams. The two lower feed waveguides are responsible for the receiving antenna, with a total of four ports, generating four beams. All eight ports are connected to waveguide isolators, with port 1 being the input port, and ports 2, 3, and 4 being the isolators that act as reverse load absorbers.

[0080] The number and wavelength of the radiation waveguides of the transmitting antenna and the receiving antenna are determined according to the antenna size and the frequency of the radar;

[0081] The spacing between each slot of the narrow-side slotted waveguide is determined according to the X-beam pointing angle of the antenna pattern;

[0082] The spacing of the feed waveguide slots is determined according to the Y-direction beam pointing angle of the antenna pattern;

[0083] The inclination angle and penetration depth of each slot in the narrow-side slotted waveguide are determined according to the amplitude distribution function and coupling function to meet the requirements of the antenna pattern side lobe.

[0084] The transmitting and receiving waveguides are staggered to ensure consistent spacing. The height is arranged according to the actual size requirements to ensure the highest possible isolation between the transmitting and receiving antennas.

[0085] More specifically, the antenna's structural dimensions are no more than 400mm x 200mm x 30mm. The transmitting and receiving antennas each have 11 radiating waveguides. Each radiating waveguide has 36 narrow slots with staggered angles, which radiate electromagnetic energy into space. The radiating slots are spaced 11mm apart, and the radiating waveguide cavity dimensions are 17mm x 4mm. The feed waveguide dimensions are 18.75mm x 4mm.

[0086] Specifically, in step S3, the second velocity data based on the carrier coordinate system is obtained by coordinate conversion of the velocity data based on the celestial coordinate system;

[0087] More specifically, the second velocity measurement data is obtained by converting the east, north, and sky axes velocities in the celestial coordinate system calculated based on the navigation satellite data into the X, Y, and Z axes velocities in the carrier coordinate system using the pitch angle, roll angle, and heading angle of the carrier; wherein the conversion formula is:

[0088]

[0089] Where γ, θ, and ψ are the roll angle, pitch angle, and heading angle of the carrier; are the velocity components of the east, north and celestial axes in the celestial coordinate system; are the three-axis velocity components in the carrier coordinate system.

[0090] Specifically, in step S4, the first speed measurement data and the second speed measurement data are interpolated and fused point by point using the same time base to obtain fused data;

[0091] The time base can be system time or satellite UTC time. The first speed measurement data and the second speed measurement data at the same time point are arranged at intervals by difference, which is convenient for subsequent processing.

[0092] Specifically, step S5 calculates the three-axis velocity difference and scale factor difference of each data point in the fused data; including:

[0093] According to the Doppler radar speed difference formula Calculate the velocity difference of the three axes; where: are the velocity components of the east, north and celestial axes in the celestial coordinate system; are the three-axis velocity components in the carrier coordinate system.

[0094] According to the Doppler radar scale coefficient difference formula Calculate the difference of the three-axis scale coefficients; where δV i D is the velocity difference of the three axes; V i G The three-axis velocity of the second velocity measurement data, i=X, Y, Z.

[0095] Specifically, in step S6, before calibrating the three-axis velocity error, scale factor error stability and random noise of the Doppler radar according to the three-axis velocity difference and the scale factor difference, the error obtained in step S5 is calibrated. δk X ,δk Y ,δk Z Perform sliding average, the sliding window width can be set according to the number of sampling points (such as 200 points), and the obtained data is used as the accuracy statistical sample; Subtract the corresponding smoothed data and use the obtained data as random error statistical sample data for smoothing;

[0096] More specifically, in step S6, the calibration of the three-axis velocity error includes:

[0097] 1) Determine whether the speed difference in each axis is greater than a preset speed difference threshold;

[0098] The speed difference threshold can be set according to specific requirements of calibration.

[0099] 2) If the error is greater than the threshold, the root mean square of the scale coefficient difference in the axis is used as the velocity error in the axis for calibration;

[0100] The root mean square calculation formula used is: Where N is the number of samples of scale factor difference, δk i,j is the j-th scale factor difference in the axis (i=X, Y or Z).

[0101] 3) is less than the threshold. Since the scale coefficient difference of the axis cannot accurately represent the speed error, the standard deviation of the speed difference of the axis is used as the speed error of the axis for calibration.

[0102] The standard deviation calculation formula used is: Where N is the number of speed difference samples, is the j-th velocity difference in the axial direction (i=X, Y or Z).

[0103] By selecting different velocity error calibration methods for different axes according to the set velocity difference threshold, the radar's forward velocity error, lateral velocity error, and vertical velocity error can all be accurately calibrated, thereby achieving velocity error accuracy analysis of the three axes of the Doppler radar.

[0104] More specifically, in step S6, in addition to calibrating the forward velocity error, lateral velocity error, and vertical velocity error of the radar, the calibration coefficient error stability and the axial random noise are also calibrated.

[0105] The calibration coefficient error stability is calibrated as the standard deviation of the calibration coefficient difference.

[0106] The standard deviation calculation formula used is: Where N is the number of samples of velocity difference, δk i,j is the j-th scale factor difference along the i-axis (i=X, Y or Z).

[0107] The axial random noise is calibrated as the root mean square of the axial velocity differences.

[0108] The root mean square calculation formula used is Where N is the number of samples of scale factor difference, is the j-th axial velocity difference in the i-axis direction (i=X, Y or Z).

[0109] In summary, the Doppler radar velocity measurement accuracy calibration method disclosed in the present invention is applicable to the analysis of the Doppler radar velocity measurement accuracy of an aircraft under any terrain, any flight track, and any time segment. It realizes the calibration of the three-axis velocity error, scale factor error stability, and random noise of the Doppler radar, conducts a comprehensive assessment of the Doppler radar, and contributes to the continuous improvement of the Doppler radar.

[0110] Another embodiment of the present invention discloses a device for calibrating the Doppler radar speed measurement accuracy, such as Figure 4 Shown, including:

[0111] A preprocessing module, used for preprocessing the collected Doppler frequency data and navigation satellite data;

[0112] A first speed measurement data calculation module is used to perform speed measurement calculation according to the preprocessed Doppler frequency to obtain first speed measurement data based on the carrier coordinate system;

[0113] A second speed measurement data calculation module is used to calculate speed data based on a celestial coordinate system according to the preprocessed navigation satellite data, and obtain second speed measurement data based on a carrier coordinate system through coordinate conversion;

[0114] An interpolation and fusion module is used to interpolate and fuse the first speed measurement data and the second speed measurement data point by point using the same time base;

[0115] The difference calculation module is used to calculate the three-axis velocity difference and scale coefficient difference of each data point of the fused data;

[0116] The parameter calibration module is used to calculate the three-axis velocity error, the scale coefficient error stability and the random noise according to the three-axis velocity difference and the scale coefficient difference, so as to calibrate the speed measurement accuracy of the Doppler radar.

[0117] Specifically, the parameter calibration module includes a first calibration module, a second calibration module and a third calibration module;

[0118] The first calibration module is used to calibrate the three-axis velocity error parameters of Doppler radar velocity measurement;

[0119] The second calibration module is used to calibrate the scale coefficient error stability parameter of the Doppler radar speed measurement;

[0120] The third calibration module is used to calibrate the random noise parameters of Doppler radar speed measurement.

[0121] More specifically, the calibration of the three-axis velocity error parameters by the first calibration module includes:

[0122] 1) Determine whether the speed difference in each axis is greater than a preset speed difference threshold;

[0123] 2) If the error is greater than the threshold, the root mean square of the scale coefficient difference in the axis is used as the velocity error in the axis for calibration;

[0124] 3) If the value is less than the threshold, the standard deviation of the velocity difference in the axis is used as the velocity error in the axis for calibration.

[0125] Other specific details and beneficial effects of this embodiment are the same as those of the previous embodiment and will not be described in detail here.

[0126] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A Doppler radar velocity measurement accuracy calibration method, characterized in that: The steps include: Preprocessing the collected Doppler frequency data and navigation satellite data; Performing velocity measurement calculation according to the pre-processed Doppler frequency to obtain first velocity measurement data based on the carrier coordinate system; Calculating velocity data based on a celestial coordinate system according to the preprocessed navigation satellite data, and obtaining second velocity measurement data based on a carrier coordinate system through coordinate conversion; Using the same time base, interpolating and fusing the first speed measurement data and the second speed measurement data point by point to obtain fused data; Calculate the three-axis velocity difference and scale factor difference of each data point in the fused data; Calibrate the three-axis velocity error, scale factor error stability and random noise of the Doppler radar according to the three-axis velocity difference and the scale factor difference; The Doppler radar antenna uses a four-beam traveling waveguide antenna with a co-aperture integrated design for both the transmitting and receiving antennas. Both the transmitting and receiving antennas of the four-beam traveling waveguide antenna have four beams with strictly symmetrical beam pointing angles. The precise flight speed of the aircraft in three directions is calculated by using the relationship between the Doppler frequency shift and the beam pointing angle. The receiving or transmitting antenna adopts a traveling wave array with slots on the narrow side of the waveguide. The radiating waveguides of the transmitting and receiving antennas are arranged in a staggered manner. The radiating waveguides of the transmitting and receiving antennas are arranged in a high-low manner in the same plane, so that the respective feeding waveguides feed the transmitting and receiving antennas respectively. The four-beam traveling wave waveguide antenna consists of several radiating waveguides and four feeding waveguides. Each radiating waveguide is a narrow-side slotted waveguide with the same structure. The two upper feeding waveguides are responsible for transmitting the antenna, with a total of four ports, generating four beams; The two feeding waveguides on the lower layer are responsible for the receiving antenna, with a total of four ports, generating four beams; The Doppler radar includes four radar beams in a centrally symmetrical X shape; the Doppler frequency data includes the Doppler frequency f collected by the first radar beam d1 , the Doppler frequency f collected by the second radar beam d2 , the Doppler frequency f collected by the third radar beam d3 and the Doppler frequency f collected by the fourth radar beam d4 ; When the system detects only positive frequencies and the forward speed is much greater than the lateral and vertical speeds, the first speed measurement data includes: Where, are the velocity components of the carrier coordinate system X, Y, and Z axes measured by the Doppler radar; γ0 is the angle between the beam centerline and the X axis of the carrier coordinate system; δ0 is the angle between the projection of the beam line on the corresponding plane and the Y axis of the carrier coordinate system; λ is the wavelength of the radar transmission signal.

2. The Doppler radar velocity measurement accuracy calibration method according to claim 1, characterized in that: The second velocity measurement data is obtained by converting the east, north, and sky axes velocities in the celestial coordinate system calculated based on the navigation satellite data into the X, Y, and Z axes velocities in the carrier coordinate system using the carrier's pitch angle, roll angle, and heading angle. The conversion formula is: Where γ, θ, and ψ are the roll angle, pitch angle, and heading angle of the carrier; are the velocity components of the east, north and celestial axes in the celestial coordinate system; are the three-axis velocity components in the carrier coordinate system.

3. The Doppler radar velocity measurement accuracy calibration method according to claim 1, characterized in that: The calibration of the three-axis velocity error includes: 1) Determine whether the speed difference in each axis is greater than a preset speed difference threshold; 2) If the error is greater than the threshold, the root mean square of the scale coefficient difference in the axis is used as the velocity error in the axis for calibration; 3) If the value is less than the threshold, the standard deviation of the velocity difference in the axis is used as the velocity error in the axis for calibration.

4. The Doppler radar velocity measurement accuracy calibration method according to claim 1, characterized in that: The calibration coefficient error stability is calibrated as the standard deviation of the calibration coefficient difference.

5. The Doppler radar velocity measurement accuracy calibration method according to claim 1, characterized in that: The axial random noise is calibrated as the root mean square of the axial velocity differences.

6. The Doppler radar velocity measurement accuracy calibration method according to any one of claims 1 to 5, characterized in that: The Doppler radar calibration coefficient difference Where, δV i D is the velocity difference of the three axes; V i G The three-axis velocity of the second velocity measurement data, i=X, Y, Z.

7. A Doppler radar velocity measurement accuracy calibration device, characterized in that: include, A preprocessing module, used for preprocessing the collected Doppler frequency data and navigation satellite data; A first speed measurement data calculation module is used to perform speed measurement calculation according to the preprocessed Doppler frequency to obtain first speed measurement data based on the carrier coordinate system; A second speed measurement data calculation module is used to calculate speed data based on a celestial coordinate system according to the preprocessed navigation satellite data, and obtain second speed measurement data based on a carrier coordinate system through coordinate conversion; An interpolation and fusion module is used to interpolate and fuse the first speed measurement data and the second speed measurement data point by point using the same time base; The difference calculation module is used to calculate the three-axis velocity difference and scale coefficient difference of each data point of the fused data; A parameter calibration module is used to calculate the three-axis velocity error, the scale coefficient error stability and the random noise according to the three-axis velocity difference and the scale coefficient difference, so as to calibrate the speed measurement accuracy of the Doppler radar; The Doppler radar antenna uses a four-beam traveling waveguide antenna with a co-aperture integrated design for both the transmitting and receiving antennas. Both the transmitting and receiving antennas of the four-beam traveling waveguide antenna have four beams with strictly symmetrical beam pointing angles. The precise flight speed of the aircraft in three directions is calculated by using the relationship between the Doppler frequency shift and the beam pointing angle. The receiving or transmitting antenna adopts a traveling wave array with slots on the narrow side of the waveguide. The radiating waveguides of the transmitting and receiving antennas are staggered and placed high and low, so that the respective feeding waveguides feed the transmitting and receiving antennas respectively. The four-beam traveling wave waveguide antenna consists of several radiating waveguides and four feeding waveguides. Each radiating waveguide is a narrow-side slotted waveguide with the same structure. The two upper feeding waveguides are responsible for transmitting the antenna, with a total of four ports, generating four beams; The two feeding waveguides on the lower layer are responsible for the receiving antenna, with a total of four ports, generating four beams; The Doppler radar includes four radar beams in a centrally symmetrical X shape; the Doppler frequency data includes the Doppler frequency f collected by the first radar beam d1 , the Doppler frequency f collected by the second radar beam d2 , the Doppler frequency f collected by the third radar beam d3 and the Doppler frequency f collected by the fourth radar beam d4 ; When the system detects only positive frequencies and the forward speed is much greater than the lateral and vertical speeds, the first speed measurement data includes: Where, are the velocity components of the carrier coordinate system X, Y, and Z axes measured by the Doppler radar; γ0 is the angle between the beam centerline and the X axis of the carrier coordinate system; δ0 is the angle between the projection of the beam line on the corresponding plane and the Y axis of the carrier coordinate system; λ is the wavelength of the radar transmission signal.

8. The Doppler radar velocity measurement accuracy calibration device according to claim 7, characterized in that: The parameter calibration module includes a first calibration module, a second calibration module and a third calibration module; The first calibration module is used to calibrate the three-axis velocity error parameters of Doppler radar velocity measurement; The second calibration module is used to calibrate the scale coefficient error stability parameter of the Doppler radar speed measurement; The third calibration module is used to calibrate the random noise parameters of Doppler radar speed measurement.

9. The Doppler radar speed measurement accuracy calibration device according to claim 7, characterized in that: The calibration of the three-axis velocity error parameters by the first calibration module includes: 1) Determine whether the speed difference in each axis is greater than a preset speed difference threshold; 2) If the error is greater than the threshold, the root mean square of the scale coefficient difference in the axis is used as the velocity error in the axis for calibration; 3) If the value is less than the threshold, the standard deviation of the velocity difference in the axis is used as the velocity error in the axis for calibration.

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