A method and system for correcting the neutral atmosphere delay error of a VLBI station

Abstract

The present invention belongs to the technical field of deep space exploration, and discloses a method and system for correcting the neutral atmosphere time delay error of a VLBI station. The method calculates the altitude and azimuth information in the direction from the VLBI station to the detector and the altitude and azimuth information in the direction from the VLBI station to the radio source; performs fusion to generate a guiding file in the order of observation time; obtains the sampled neutral atmosphere time delay; calculates the neutral atmosphere time delay rate according to the set of neutral atmosphere time delays of the VLBI station; based on the observation outline, decomposes the neutral atmosphere time delay and time delay rate corresponding to the observation moments of the detector and the radio source, and outputs them to different files respectively. The present invention can effectively improve the result of real-time correction of the neutral atmosphere time delay of the VLBI station.

Description

Technical Field

[0001] The present invention belongs to the technical field of deep space exploration, and particularly relates to a method and system for correcting the neutral atmosphere time delay error of a VLBI station. Background Technique

[0002] The VLBI orbit determination subsystem of the TT&C system is an important part of China's deep space exploration. Its task is to determine the orbit of the detector by using the Very Long Baseline Interferometry (VLBI) technology. The influence of the neutral atmosphere time delay is the main error source for orbit determination by the VLBI technology. The neutral atmosphere time delay varies with the elevation angle. The dry time delay of the neutral atmosphere in the zenith direction is about 2.3 meters, and the wet time delay is on the order of decimeters (Nilsson et al., 2013). When the elevation angle is 6°, the neutral atmosphere time delay can reach 20 meters. At present, the international community mainly eliminates the neutral atmosphere time delay in real time through the zenith time delay model and the mapping function. The correction accuracy in the zenith direction is at the centimeter level, and the correction accuracy in the 10° elevation angle direction is about at the decimeter level, which limits the improvement of the orbit determination accuracy of the VLBI technology for the detector and is a key problem that needs to be solved urgently for the continuous development of deep space exploration.

[0003] The Water Vapor Radiometer (WVR) can measure in real time the influence of the neutral atmosphere on the propagation of radio signals in the propagation path. Research shows that the accuracy of the neutral atmosphere wet delay measured by the international WVR in the zenith direction is better than 1 cm. Based on its high accuracy and high timeliness, the microwave radiometer can be used to measure the neutral atmosphere time delay in the observation direction from the radio telescope to the detector. However, due to the alternating observation of the detector and the radio source in deep space exploration, the microwave radiometer cannot be directly used at present. Summary of the Invention

[0004] To overcome the problems existing in the related technologies, the disclosed embodiments of the present invention provide a method and system for correcting the neutral atmosphere time delay error of a VLBI station, particularly a method for correcting the neutral atmosphere time delay error of a VLBI station based on a microwave radiometer, and a method for directly observing a microwave radiometer that integrates a detector and a radio source.

[0005] The technical solution is as follows: The method for correcting the neutral atmosphere time delay error of a VLBI station includes:

[0006] S1: Based on the predicted ephemeris of the detector, calculate the elevation angle and azimuth angle information in the direction from the VLBI station to the detector;

[0007] S2: Based on the radio source observation file, calculate the elevation angle and azimuth angle information in the direction from the VLBI station to the radio source;

[0008] S3: Integrate the detector altitude-azimuth file and the radio source altitude-azimuth file according to the radio source observation file to generate a guiding file in the chronological order of the observation time;

[0009] S4: Automatically upload the guiding files of each station to the specified path of the corresponding microwave radiometer through a script;

[0010] S5: Eliminate the observation outliers and the observed values during the rotation of the microwave radiometer, and perform smoothing filtering on the observation results of the microwave radiometer to obtain the sampled neutral atmospheric delay;

[0011] S6: Calculate the neutral atmospheric delay rate based on the set of neutral atmospheric delays of the VLBI stations;

[0012] S7: Based on the observation program, decompose the neutral atmospheric delay and delay rate of the detector and the radio source at the corresponding observation times and output them to different files respectively.

[0013] In step S1, calculate the altitude-azimuth information in the direction from the VLBI station to the detector, including:

[0014] Convert the coordinates of the detector in the J2000 inertial coordinate system to the rectangular coordinates in the local geocentric coordinate system, correct the Earth rotation parameters, and correct the Doppler and light travel differences using the models recommended by IERS2010. The altitude information in the direction from the VLBI station to the detector is calculated by the following formula:

[0015]

[0016] [N,E,U] T =H×([X S ,Y S ,Z S T -[X R ,Y R ,Z R T )

[0017]

[0018] In the formula, Ele1 is the altitude angle between the VLBI station and the detector, a is the first tropospheric hydrostatic pressure, U is the first Coordinated Universal Time, T is the observation time, N is the first latitude, E is the first longitude, H is the first rotation matrix, [N,E,U] T is the rectangular coordinate of the detector in the local geocentric coordinate system of the VLBI station, [X S ,Y S ,Z S T is the coordinate vector of the detector in the J2000 inertial coordinate system, [X R ,Y​​​R ,Z R T is the coordinate vector of the VLBI station in the J2000 inertial coordinate system, and B, L are the first geodetic coordinates of the VLBI station.

[0019] In step S2, calculate the altitude and azimuth information in the direction from the VLBI station to the radio source, including:

[0020] Convert the coordinates of the radio source in the J2000 inertial coordinate system to rectangular coordinates in the station-centered coordinate system, correct the Earth rotation parameters, and correct the Doppler and light travel differences using the models recommended by IERS2010. The azimuth information in the direction from the VLBI station to the radio source is calculated by the following formula:

[0021]

[0022] [N', E', U'] T = H' × ([X' S , Y' S , Z' S ) T -[X' R , Y' R , Z' R ) T )

[0023]

[0024] In the formula, Ele2 is the altitude angle between the VLBI station and the radio source, a' is the second tropospheric hydrostatic, U' is the second Coordinated Universal Time, T is the observation time, N' is the second latitude, E' is the second longitude, H' is the second rotation matrix, and [N', E', U'] T is the rectangular coordinate of the radio source in the VLBI station-centered coordinate system, and [X' S , Y' S , Z' S T is the coordinate vector of the radio source in the J2000 inertial coordinate system, and [X' R , Y' R , Z' R T is the coordinate vector of the VLBI station in the J2000 inertial coordinate system, and B', L' are the second geodetic coordinates of the VLBI station.

[0025] In step S3, fuse according to the radio source observation file to generate a guiding file in the order of observation time, including:

[0026] ​If the observed radio source is set in the observation file at time t, the altitude and azimuth information of the radio source is input into the guidance file; if the observed detector is set in the observation file, the altitude and azimuth information of the detector is input into the guidance file. The formula is as follows:

[0027]

[0028] In the formula, is the altitude and azimuth in the microwave radiometer guidance file at time t, t is the observation time, t q , t s are the times in the files where the altitude and azimuth of the radio source and the detector are located respectively, are the altitude and azimuth information of the radio source and the detector at time t respectively.

[0029] In step S4, the microwave radiometer sets the automatic ambiguity tracking mode. Once a guidance file is successfully uploaded, the microwave radiometer converts the guidance file into a recognizable format and starts ambiguity tracking observation according to the time, altitude, and azimuth information in the guidance file. Specifically, it includes:

[0030] S401, establish a set of tracking behavior attributes for time, altitude, and azimuth output information: divide the collected tracking behavior data of time, altitude, and azimuth output information into m tracking behavior attributes of time, altitude, and azimuth output information according to the characteristics of time, altitude, and azimuth output information tracking behavior; automatically set the observation direction of the microwave radiometer according to the altitude and azimuth data of each tracking behavior attribute of time, altitude, and azimuth output information.

[0031] S402, the microwave radiometer matches the guidance file time information with the local time. If the match is successful, the microwave radiometer rotates the antenna to the specified direction according to the altitude and azimuth information corresponding to the guidance file time; if the match is unsuccessful, the microwave radiometer continues to wait.

[0032] S403, the microwave radiometer automatically stores the observation results in the local machine in a specified format; the file content includes time, temperature, humidity, pressure, total delay, dry delay, and wet delay information. The file length is 1 minute and the sampling rate is 1 second.

[0033] Furthermore, averaging is first performed in the 1-minute-long file. In order to eliminate outliers, threshold judgment is performed after averaging. If the time delay data at a certain time point exceeds three times the average value, it is eliminated and then averaged again, and so on.

[0034] In step S6, calculate the neutral atmospheric delay rate. The formula is as follows:

[0035]

[0036] In the formula, TSTD RLet \(T_{STD}\) be the rate, and \(t_1\), \(t_2\) be adjacent times. They are the total neutral atmosphere time delays \(T_{STD}\) observed by the microwave radiometer at times \(t_1\) and \(t_2\) respectively.

[0037] Another object of the present invention is to provide a neutral atmosphere time delay error correction system for a VLBI station. This system implements the neutral atmosphere time delay error correction method for the VLBI station, and the system includes:

[0038] A detector direction altitude-azimuth calculation module, which is used to calculate the altitude-azimuth information in the direction from the VLBI station to the detector based on the predicted ephemeris of the detector.

[0039] A radio source direction altitude-azimuth calculation module, which is used to calculate the altitude-azimuth information in the direction from the VLBI station to the radio source based on the radio source observation file.

[0040] A fusion module, which is used to fuse the detector altitude-azimuth file and the radio source altitude-azimuth file according to the radio source observation file to generate a guiding file in the order of observation time.

[0041] A guiding file upload module, which is used to automatically upload the guiding files of each station to the specified path of the corresponding microwave radiometer through a script.

[0042] A smoothing filter module, which is used to eliminate observation outliers and the observed values during the rotation of the microwave radiometer, and perform smoothing filtering on the observation results of the microwave radiometer to obtain the sampled neutral atmosphere time delay.

[0043] A neutral atmosphere time delay rate calculation module, which is used to calculate the neutral atmosphere time delay rate according to the set of neutral atmosphere time delays of the VLBI station.

[0044] A decomposition module, which is used to decompose the neutral atmosphere time delay and time delay rate at the corresponding observation times of the detector and the radio source based on the observation program, and output them to different files respectively.

[0045] Furthermore, the neutral atmosphere time delay error correction system for the VLBI station is carried on a computer-readable storage medium. The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the functions in the above-mentioned neutral atmosphere time delay error correction system for the VLBI station can be realized.

[0046] Combining all the above technical solutions, the beneficial effects of the present invention are as follows: The present invention can measure the neutral atmosphere time delay error of the VLBI station, which is used to weaken the influence of the neutral atmosphere time delay in the observation directions of the detector and the radio source. The microwave radiometer observation strategy of the present invention is more suitable for VLBI observation in deep space exploration. Based on the determined neutral atmosphere time delay correction method of the present invention, the measured data can be used to correct the neutral atmosphere time delay in the observations of the detector and the radio source. Compared with using the neutral atmosphere time delay prediction model, the real-time correction result of the neutral atmosphere time delay at the VLBI station can be effectively improved. Description of the Drawings

[0047] The accompanying drawings herein are incorporated into the specification and form a part of the specification, showing embodiments consistent with the present disclosure, and are used together with the specification to explain the principles of the present disclosure;

[0048] Figure 1 It is a flowchart of the method for correcting the neutral atmosphere time delay error of the VLBI station provided by the embodiment of the present invention;

[0049] Figure 2 It is a schematic diagram of the principle of the method for correcting the neutral atmosphere time delay error of the VLBI station provided by the embodiment of the present invention;

[0050] Figure 3 It is a system diagram of the method for correcting the neutral atmosphere time delay error of the VLBI station provided by the embodiment of the present invention;

[0051] Figure 4 It is a neutral atmosphere time delay diagram measured by the Tianma VLBI station during the observation of the Tianwen-1 detector;

[0052] Figure 5 It is a difference diagram based on the difference between the neutral atmosphere time delay of the microwave radiometer and the result of the zenith time delay prediction + VMF3 mapping function;

[0053] In the figure: 1. Detector direction altitude and azimuth calculation module; 2. Radio source direction altitude and azimuth calculation module; 3. Fusion module; 4. Guide file upload module; 5. Smoothing filter module; 6. Neutral atmosphere time delay rate calculation module; 7. Decomposition module. Specific Embodiments

[0054] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following detailed description of the specific embodiments of the present invention will be made with reference to the accompanying drawings. Many specific details are set forth in the following description in order to fully understand the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0055] Example 1, as Figure 1As shown in the figure, the method for correcting the neutral atmospheric delay error of the VLBI station provided by the embodiment of the present invention includes:

[0056] S1: Based on the predicted ephemeris of the detector, calculate the altitude and azimuth information in the direction from the VLBI station to the detector;

[0057] S2: Based on the observed file of the radio source, calculate the altitude and azimuth information in the direction from the VLBI station to the radio source;

[0058] S3: Integrate the detector altitude and azimuth file and the radio source altitude and azimuth file according to the observed file of the radio source to generate a guiding file in the order of observation time;

[0059] S4: Automatically upload the guiding file of each station to the specified path of the corresponding microwave radiometer through a script;

[0060] S5: Eliminate the observation outliers and the observed values during the rotation of the microwave radiometer, and perform smoothing filtering on the observed results of the microwave radiometer to obtain the sampled neutral atmospheric delay;

[0061] S6: Calculate the neutral atmospheric delay rate according to the set of neutral atmospheric delays of the VLBI station;

[0062] S7: Based on the observation outline, decompose the neutral atmospheric delay and delay rate at the corresponding observation times of the detector and the radio source, and output them to different files respectively.

[0063] Exemplarily, in step S1, calculating the altitude and azimuth information in the direction from the VLBI station to the detector includes:

[0064] Convert the coordinates of the detector in the J2000 inertial coordinate system to the rectangular coordinates in the station-centered coordinate system, correct the Earth rotation parameters, and correct the Doppler and light travel differences using the models recommended by IERS2010. The altitude information in the direction from the VLBI station to the detector is calculated by the following formula:

[0065]

[0066] {N,E,U] T =H×([X S ,Y S ,Z S T -[X R ,Y R ,Z R T )

[0067]

[0068] ​​Wherein, Ele1 is the altitude angle between the VLBI station and the detector, a is the first tropospheric hydrostatic force, U is the first Coordinated Universal Time, T is the observation time, N is the first latitude, E is the first longitude, H is the first rotation matrix, [N, E, U] T is the rectangular coordinate of the detector in the VLBI station-centered coordinate system, [X S , Y S , Z S T is the coordinate vector of the detector in the J2000 inertial coordinate system, [X R , Y R , Z R T is the coordinate vector of the VLBI station in the J2000 inertial coordinate system, B, L are the first geodetic coordinates of the VLBI station.

[0069] Exemplarily, in step S2, calculating the altitude angle and azimuth angle information in the direction from the VLBI station to the radio source includes:

[0070] Converting the coordinates of the radio source in the J2000 inertial coordinate system into rectangular coordinates in the station-centered coordinate system, correcting the earth rotation parameters, and correcting the Doppler and light travel differences using the models recommended by IERS2010. The azimuth angle information in the direction from the VLBI station to the radio source is calculated by the following formula:

[0071]

[0072] [N', E', U'] T = H' × ([X' S , Y' S , Z'S] T - [X' R , Y' R , Z' R T )

[0073]

[0074] Wherein, Ele2 is the altitude angle between the VLBI station and the radio source, a' is the second tropospheric hydrostatic force, U' is the second Coordinated Universal Time, T is the observation time, N' is the second latitude, E' is the second longitude, H' is the second rotation matrix, [N', E', U'] T is the rectangular coordinate of the radio source in the VLBI station-centered coordinate system, [X' S , Y' S , Z' S T is the coordinate vector of the radio source in the J2000 inertial coordinate system, [X' R , Y' R ​​​​,Z' R T is the coordinate vector of the VLBI station in the J2000 inertial coordinate system, and B', L' are the second geodetic coordinates of the VLBI station.

[0075] Another exemplary one is that in step S3, according to the radio source observation file, fusion is performed to generate a guiding file in the order of observation time, including:

[0076] If the radio source to be observed is set in the observation file at time t, the altitude and azimuth information of the radio source is input into the guiding file; if the detector to be observed is set in the observation file, the altitude and azimuth information of the detector is input into the guiding file. The formula is as follows:

[0077]

[0078] In the formula, is the altitude and azimuth in the guiding file of the microwave radiometer at time t, t is the observation time, t q ,t s are the times in the files where the altitude and azimuth of the radio source and the detector are located respectively, are the altitude and azimuth information of the radio source and the detector at time t respectively.

[0079] Another exemplary one is that in step S4, the microwave radiometer sets the automatic ambiguity tracking mode. Once a guiding file is successfully uploaded, the microwave radiometer converts the guiding file into a recognizable format and starts the ambiguity tracking observation according to the time, altitude, and azimuth information in the guiding file. Specifically, it includes:

[0080] S401, establish a set of tracking behavior attributes for time, altitude, and azimuth output information: divide the collected tracking behavior data of time, altitude, and azimuth output information into m tracking behavior attributes for time, altitude, and azimuth output information according to the tracking behavior characteristics of time, altitude, and azimuth output information; according to the altitude and azimuth data of each tracking behavior attribute for time, altitude, and azimuth output information, automatically set the observation direction of the microwave radiometer;

[0081] S402, the microwave radiometer matches the guiding file time information with the local time. If the match is successful, the microwave radiometer rotates the antenna to the specified direction according to the altitude and azimuth information corresponding to the guiding file time; if the match is unsuccessful, the microwave radiometer continues to wait;

[0082] S403, the microwave radiometer automatically stores the observation results in the local machine in a specified format; the file content includes time, temperature, humidity, pressure, total delay, dry delay, and wet delay information, the file length is 1 minute, and the sampling rate is 1 second.

[0083] ​Among them, for the 1-minute long file, averaging is first performed. To eliminate outliers, threshold judgment is carried out after averaging. If the time delay data at a certain time point exceeds three times the average value, it is eliminated and then averaged again, and so on for iteration.

[0084] Another exemplary one is that in step S6, the neutral atmospheric delay rate is calculated, and the formula is as follows:

[0085]

[0086] In the formula, TSTD R is the TSTD rate, t1 and t2 are adjacent times, and are the total neutral atmospheric delays TSTD observed by the microwave radiometer at times t1 and t2 respectively.

[0087] Figure 2 is the schematic diagram of the neutral atmospheric delay error correction method for the VLBI station provided by the embodiment of the present invention. The present invention fuses the detector altitude-azimuth file and the radio source altitude-azimuth file according to the radio source observation file to generate a guiding file in the order of observation time, which provides sufficient guarantee conditions for the microwave radiometer to obtain the sampled neutral atmospheric delay.

[0088] The fuzzy comprehensive evaluation system proposed by the present invention calculates the relationship between the output information tracking behavior of time-altitude-azimuth and the grade set, and obtains the membership matrix of the output information tracking behavior of time-altitude-azimuth. That is, it describes the uncertainty and ambiguity of the output information tracking behavior of time-altitude-azimuth through the output information tracking behavior of time-altitude-azimuth, and reflects the membership relationship of the output information tracking behavior attributes of time-altitude-azimuth to different grades through the association relationship between the output information tracking behavior of time-altitude-azimuth and the grade set. This way is more in line with objective facts. In addition, since the present invention uses the 'weight method' to adaptively allocate attribute weights and assigns different weights according to the different contributions of the output information tracking behavior attributes of each time-altitude-azimuth to the evaluation result, it further reduces subjectivity and improves the accuracy of the evaluation result.

[0089] Embodiment 2, as Figure 3 shown, the neutral atmospheric delay error correction system for the VLBI station provided by the embodiment of the present invention includes:

[0090] The detector direction altitude-azimuth calculation module 1 is used to calculate the altitude-azimuth information in the direction from the VLBI station to the detector based on the detector predicted ephemeris;

[0091] The radio source direction altitude-azimuth calculation module 2 is used to calculate the altitude-azimuth information in the direction from the VLBI station to the radio source based on the radio source observation file;

[0092] Fusion module 3, used to fuse the detector elevation angle azimuth angle file and the radio source elevation angle azimuth angle file according to the radio source observation file, and generate a guide file in the order of observation time;

[0093] The boot file upload module 4 is used to automatically upload the boot files of each station to the designated path of the corresponding microwave radiometer through a script;

[0094] Smoothing filter module 5, used to remove observation abnormal values ​​and observation quantities when the microwave radiometer rotates, and smooth the microwave radiometer observation results to obtain the sampled neutral atmosphere delay;

[0095] A neutral atmosphere delay rate calculation module 6, used to calculate the neutral atmosphere delay rate according to the neutral atmosphere delay set of the VLBI station;

[0096] The decomposition module 7 is used to decompose the neutral atmosphere delay and delay rate of the detector and the radio source at the corresponding observation time based on the observation outline, and output them to different files respectively.

[0097] In order to further illustrate the relevant effects of the embodiments of the present invention, the following experiment was conducted: The present invention selected the observation data of a VLBI station in a certain area on May 15, 2021 for experiment.

[0098] Get the altitude and azimuth: first write a program to read the predicted ephemeris and observation outline data of the Tianwen-1 probe, and then calculate the altitude and azimuth from the station to the probe and the radio source based on the Tianma station coordinates, the Earth's rotation parameter file, etc., and output the results to files respectively.

[0099] Merge elevation and azimuth file: Since the calculated detector elevation and azimuth are complete data covering the 1-minute sampling of the observation arc, the detector and the radio source are observed alternately during real-time observation. Therefore, the detector and radio source elevation and azimuth are merged into one file as the guide file for microwave radiometer observation.

[0100] Automatically upload the guide file and observe: Write a program to automatically upload the guide file and start it before the real-time observation begins. The microwave radiometer is set to automatic fuzzy tracking mode. Once a guide file is successfully uploaded, the microwave radiometer converts the guide file into a recognizable format and starts fuzzy tracking observation according to the time altitude angle azimuth information in the guide file.

[0101] Microwave radiometer observation delay processing: The microwave radiometer samples for 1 second. In order to obtain the neutral atmosphere delay of 1 minute sampling, the observation data is preprocessed by smoothing filtering. Outliers and observations when the microwave radiometer is rotating are eliminated.

[0102] Calculate the neutral atmosphere delay rate: Calculate the delay rate by taking the difference between the delay rate sets and dividing it by the time difference.

[0103] Among them, the Global Mapping Function (GMF) is used to map the zenith calibration of the microwave radiometer to the slant aiming direction, which is one of the accurate mapping functions in real time. The GMF formula is as follows:

[0104]

[0105] The parameters a, b, and c of the tropospheric hydrostatic and wet components are different. These parameters are calculated using the monthly average profiles of pressure, temperature, and humidity of the 40-year reanalysis data of the European Centre for Medium-Range Weather Forecasts (ECMWF) on a 15°×15° global grid. According to the observation program, the neutral atmospheric time delay and time delay rate corresponding to the Tianwen-1 probe and the radio source in the observation arc on May 15, 2021 are decomposed and output to different files respectively.

[0106] Among them, Figure 4 is the neutral atmospheric time delay map measured by the Tianma VLBI station during the observation of the Tianwen-1 probe. The brown color represents the elevation angle sequence, the black color is based on the results of the microwave radiometer, and the green color is the result of the zenith time delay prediction + VMF3 mapping function; Figure 5 is the difference map based on the neutral atmospheric time delay of the microwave radiometer and the result of the zenith time delay prediction + VMF3 mapping function; it shows that the results directly observed by the microwave radiometer can be used in real time for the correction of the neutral atmospheric time delay of the station.

[0107] As mentioned above, it is only a relatively preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be covered by the protection scope of the present invention.

Claims

1. A method for correcting neutral atmosphere delay error of a VLBI station, characterized in that: The method includes: S1: Calculate the altitude and azimuth information from the VLBI station to the detector based on the detector's predicted ephemeris; S2: Based on the radio source observation file, calculate the elevation angle and azimuth information from the VLBI station to the radio source; S3: Fusing the detector elevation angle azimuth file and the radio source elevation angle azimuth file according to the radio source observation file to generate a guide file in the order of observation time; S4: Automatically upload each station’s boot file to the specified path of the corresponding microwave radiometer through the script; S5: Eliminate observation anomalies and observations during the rotation of the microwave radiometer, smooth and filter the microwave radiometer observation results, and obtain the sampled neutral atmosphere delay; S6: Calculate the neutral atmosphere delay rate based on the VLBI station neutral atmosphere delay set; S7: Based on the observation outline, decompose the neutral atmosphere delay and delay rate of the detector and radio source at the corresponding observation time, and output them to different files respectively.

2. The VLBI station neutral atmosphere delay error correction method according to claim 1, characterized in that: In step S1, the elevation angle azimuth information in the direction from the VLBI station to the detector is calculated, including: The coordinates of the detector in the J2000 inertial coordinate system are converted into rectangular coordinates in the station center coordinate system, the earth rotation parameters are corrected, and the Doppler and aberration are corrected using the model recommended by IERS2010. The elevation angle information from the VLBI station to the detector is calculated using the following formula: [N,E,U] T =H×([X S ,Y S ,Z S ] T -[X R ,Y R ,Z R ] T ) Where Ele1 is the altitude angle between the VLBI station and the detector, a is the first tropospheric hydrostatic force, U is the first coordinated universal time, T is the observation time, N is the first latitude, E is the first longitude, H is the first rotation matrix, [N,E,U] T is the rectangular coordinate of the detector in the VLBI station center coordinate system, [X S ,Y S ,Z S ] T is the coordinate vector of the detector in the J2000 inertial coordinate system, [X R ,Y R ,Z R ] T is the coordinate vector of the VLBI station in the J2000 inertial coordinate system, and B and L are the first geodetic coordinates of the VLBI station.

3. The VLBI station neutral atmosphere delay error correction method according to claim 1, characterized in that: In step S2, the elevation angle azimuth information in the direction from the VLBI station to the radio source is calculated, including: The coordinates of the radio source in the J2000 inertial coordinate system are converted into rectangular coordinates in the station center coordinate system, the earth rotation parameters are corrected, and the Doppler and aberration are corrected using the model recommended by IERS2010. The azimuth information from the VLBI station to the radio source is calculated using the following formula: Where Ele2 is the elevation angle between the VLBI station and the radio source, a' is the second tropospheric hydrostatic force, U' is the second coordinated universal time, T is the observation time, N' is the second latitude, E' is the second longitude, H' is the second rotation matrix, [N', E', U'] T is the rectangular coordinate of the radio source in the VLBI station center coordinate system, [X' S ,Y' S ,Z' S ] T is the coordinate vector of the radio source in the J2000 inertial coordinate system, [X' R ,Y' R ,Z' R ] T is the coordinate vector of the VLBI station in the J2000 inertial coordinate system, and B', L' are the second geodetic coordinates of the VLBI station.

4. The VLBI station neutral atmosphere delay error correction method according to claim 1, characterized in that: In step S3, the radio source observation files are fused to generate a guide file in the order of observation time, including: If the observation file is set to observe the radio source at time t, the elevation angle azimuth information of the radio source is entered in the guide file; if the observation file is set to observe the detector, the elevation angle azimuth information of the detector is entered in the guide file. The formula is as follows: In the formula, is the altitude angle azimuth in the microwave radiometer guidance file at time t, t is the observation time, t q ,t s are the time in the file where the radio source and detector altitude angle and azimuth are located respectively, They are respectively the altitude and azimuth information of the radio source and the detector at time t.

5. The VLBI station neutral atmosphere delay error correction method according to claim 1, characterized in that: In step S4, the microwave radiometer sets the automatic fuzzy tracking mode. Once a guide file is uploaded successfully, the microwave radiometer converts the guide file into a recognizable format and starts fuzzy tracking observation according to the time elevation angle and azimuth angle information in the guide file.

6. The method for correcting neutral atmosphere delay error of a VLBI station according to claim 5, characterized in that: Start fuzzy tracking observation according to the time elevation angle and azimuth angle information in the guide file, including: S401, establishing a time-elevation-azimuth output information tracking behavior attribute set: dividing the collected time-elevation-azimuth output information tracking behavior data into m time-elevation-azimuth output information tracking behavior attributes according to the time-elevation-azimuth output information tracking behavior characteristics; automatically setting the microwave radiometer observation direction according to the elevation angle azimuth output information tracking behavior attribute of each time-elevation-azimuth output information tracking behavior attribute; S402, the microwave radiometer matches the time information of the guidance file with the local time. If the match is successful, the microwave radiometer moves the antenna to the specified direction according to the altitude and azimuth information corresponding to the guidance file time; if the match is unsuccessful, the microwave radiometer continues to wait; S403, the microwave radiometer automatically saves the observation results in the specified format through the guide file into the machine; the file content includes time, temperature, humidity, pressure, total delay, dry delay and wet delay information, the file length is 1 minute, and the sampling rate is 1 second.

7. The neutral atmosphere delay error correction method for a VLBI station according to claim 6, wherein in step S403, the 1-minute file is first averaged, and in order to remove outliers, a threshold judgment is performed after averaging. If the delay data of any time point exceeds three times the average value, it is removed and then averaged, and the process is repeated iteratively.

8. The VLBI station neutral atmosphere delay error correction method according to claim 1, characterized in that: In step S6, the neutral atmosphere delay rate is calculated using the following formula: Where, TSTD R is the TSTD rate, t1, t2 are adjacent times, are the total time delay TSTD of the neutral atmosphere observed by the microwave radiometer at times t1 and t2 respectively.

9. A VLBI station neutral atmosphere delay error correction system, characterized in that: The system implements the VLBI station neutral atmosphere delay error correction method as claimed in any one of claims 1 to 8, and the system comprises: A detector direction elevation angle azimuth angle calculation module (1) is used to calculate the elevation angle azimuth angle information from the VLBI station to the detector direction based on the detector predicted ephemeris; A radio source direction elevation angle azimuth calculation module (2) is used to calculate the elevation angle azimuth information from the VLBI station to the radio source direction based on the radio source observation file; A fusion module (3) is used to fuse the detector elevation angle azimuth angle file and the radio source elevation angle azimuth angle file according to the radio source observation file to generate a guide file in the order of observation time; A boot file upload module (4), used to automatically upload the boot file of each station to the designated path of the corresponding microwave radiometer through a script; A smoothing filter module (5) is used to remove abnormal observation values ​​and observation quantities when the microwave radiometer rotates, and to perform smoothing filtering on the observation results of the microwave radiometer to obtain a sampled neutral atmosphere delay; A neutral atmosphere delay rate calculation module (6), used for calculating the neutral atmosphere delay rate according to the neutral atmosphere delay set of the VLBI station; The decomposition module (7) is used to decompose the neutral atmosphere delay and delay rate of the detector and the radio source at the corresponding observation time based on the observation outline, and output them to different files respectively.

10. The VLBI station neutral atmosphere delay error correction system according to claim 9, characterized in that: The VLBI station neutral atmosphere time delay error correction system is mounted on a computer-readable storage medium, and the computer-readable storage medium stores a computer program. When the computer program is executed by a processor, the functions of the VLBI station neutral atmosphere time delay error correction system are realized.

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