System and method for measuring gravity potential by laser time-frequency transmission between satellite and ground

Abstract

The present invention discloses a system and method for measuring gravity potential by laser time-frequency transfer between satellite and ground. The system includes: an ephemeris preprocessing subsystem for downloading ephemeris and encrypting orbits; a clock error measurement subsystem for receiving observations and calculating clock errors between satellite and ground; a precision error processing subsystem connected to a coordinate conversion module and a clock error measurement subsystem, respectively, for eliminating link errors and evaluating error residuals; and a gravity potential conversion subsystem connected to the precision error processing subsystem for converting post-processed clock errors into gravity potential differences. Based on the general theory of relativity, the present invention uses a laser time-frequency transfer method to obtain the clock error between satellite and ground and calculate the gravity potential of a ground station, opening up a new method for measuring gravity potential by time-frequency transfer, and measuring the gravity potential at the ground station with higher accuracy.

Description

Technical Field

[0001] The invention relates to a satellite-to-ground laser time-frequency signal transmission system capable of measuring the gravity position of a ground station. Background Art

[0002] Laser time-frequency transmission is based on the satellite laser ranging (SLR) technology to transmit time-frequency signals. It requires both ground observation stations and satellites to carry high-precision optical clocks. Currently, the frequency stability and accuracy of optical clocks have reached 10 -18 At the same time, SLR technology uses the visible light band, which has a short wavelength, high frequency, good collimation, and minimal impact from the ionosphere. It has high measurement accuracy and precision. Therefore, SLR technology is the most accurate technology for satellite distance measurement, and laser time transfer is also one of the most accurate technologies for satellite-to-earth clock difference measurement.

[0003] However, laser time-frequency transfer to measure gravity potential is a completely new field. Currently, no team in the world has established a complete system. In addition, the existing error processing methods of laser time-frequency transfer used for timing cannot meet the needs of measuring gravity potential with centimeter-level accuracy. Therefore, it is urgent to establish an observation system for centimeter-level satellite-to-ground laser time-frequency transfer to measure gravity potential.

[0004] There are several error sources with great influence in the satellite laser time-frequency transmission link between the satellite and the ground, mainly including Sagnac delay, Shapiro delay and tropospheric delay. It is necessary to develop appropriate algorithm modules to calculate and process them. Summary of the invention

[0005] To overcome the deficiencies of the prior art, the present invention provides a system and method for measuring gravity potential by laser time-frequency transfer between satellite and ground, which uses the laser time-frequency transfer method to obtain the clock difference between satellite and ground and calculate the gravity potential of the ground station.

[0006] According to one aspect of the present invention, a system for measuring gravity potential by laser time-frequency transmission between satellite and ground is provided, comprising:

[0007] The ephemeris preprocessing subsystem is used to download the ephemeris and encrypt the orbit;

[0008] The clock error measurement subsystem is used to receive observations and calculate the clock error between the satellite and the ground;

[0009] A precision error processing subsystem, connected to the coordinate conversion module and the clock error measurement subsystem, is used to eliminate link errors and evaluate error residuals;

[0010] The gravity potential conversion subsystem is connected to the precision error processing subsystem and is used to convert the post-processing clock difference into the gravity potential difference.

[0011] As a further technical solution, the system also includes a coordinate conversion module, which is connected to the ephemeris preprocessing subsystem and the precision error processing subsystem respectively, and is used to convert the satellite orbit coordinates and the ground observation station coordinates from the Earth-centered Earth-fixed coordinate system to the Earth-centered inertial system.

[0012] As a further technical solution, the ephemeris preprocessing subsystem includes: a network port for downloading satellite ephemeris in real time; an original ephemeris storage module for storing original ephemeris data; an orbit encryption module for filtering the orbit data according to the ground station coordinates and the set ground station cutoff altitude angle for observation epochs, and encrypting the filtered orbit coordinates; and a post-processing ephemeris storage module for storing post-processing ephemeris data.

[0013] As a further technical solution, the clock error measurement subsystem includes: an event timing module, which is used to record the emission and echo reception time of the laser pulse at the ground station, and the time when the laser pulse arrives at the satellite; a communication module, which is used to receive the data stream of the laser pulse arrival time at the satellite recorded by the satellite-borne event timing module; and a calculation module, which is used to calculate the original clock error.

[0014] As a further technical solution, the precision error processing subsystem includes: a Sagnac delay correction module, used to eliminate the Sagnac delay error caused by the rotation of the earth; a tropospheric delay correction module, used to eliminate the delay error caused by the bending of the laser path and the decrease in propagation speed in the troposphere and evaluate the error residual; a Shapiro delay correction module, used to eliminate the delay error caused by the bending of the laser propagation path in the gravitational field and evaluate the error residual; a clock error processing module, used to eliminate the above errors from the original clock error sequence.

[0015] As a further technical solution, the gravity potential conversion subsystem includes: a clock error accuracy evaluation module, which is used to evaluate the stability of the clock error time series and evaluate whether it has reached the expected accuracy; a gravity potential calculation module, which is used to calculate the clock error time series that meets the accuracy requirements to obtain gravity potential difference data.

[0016] According to one aspect of the present invention, a method for measuring gravity potential by laser time-frequency transfer between satellite and ground is provided, comprising:

[0017] Download ephemeris and encrypt orbits;

[0018] Receive observations and calculate the satellite-ground clock error;

[0019] Eliminate link errors and evaluate the residual error to obtain the clock error time series after eliminating the error;

[0020] When the clock error time series after error elimination reaches the expected accuracy, the post-processed clock error is converted into gravity potential difference.

[0021] As a further technical solution, after downloading the ephemeris and encrypting the orbit, the method further includes: converting the satellite orbit coordinates and the ground observation station coordinates from the Earth-centered Earth-fixed coordinate system to the Earth-centered inertial system.

[0022] According to one aspect of the present invention, there is provided a satellite laser ranging station, which is equipped with the system for measuring gravity potential by laser time-frequency transmission between satellite and ground.

[0023] According to one aspect of the present specification, a non-transitory computer-readable storage medium is provided, wherein the non-transitory computer-readable storage medium stores computer instructions, wherein the computer instructions enable the computer to execute the method described above.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The present invention can quickly process the observation data of the current observation arc segment and obtain the gravity potential at the current station in real time and evaluate the accuracy through the mutual cooperation of the ephemeris preprocessing subsystem, the clock error measurement subsystem, the precision error processing subsystem and the gravity potential conversion subsystem.

[0026] (2) The present invention is based on the general theory of relativity and uses the laser time-frequency transfer method to obtain the clock difference between the satellite and the ground and calculate the gravity potential of the ground station. It has opened up a new method for measuring the gravity potential by time-frequency transfer, and can measure the gravity potential at the ground station with higher accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, a brief introduction is given below to the drawings used in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0028] Figure 1 A schematic diagram of the principle of the space-to-ground laser link of the satellite-to-ground laser time-frequency transfer system for measuring gravity potential provided in an embodiment of the present invention.

[0029] Figure 2 A schematic diagram of the overall process of the satellite-to-earth laser time-frequency transfer system for measuring gravity potential provided in an embodiment of the present invention.

[0030] Figure 3 A schematic flow chart of a method for measuring gravity potential by satellite-to-earth laser time-frequency transfer provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0031] The terms "including" and "having" and any variations thereof in the specification and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusions, for example, a process, method, system, product or apparatus comprising a series of steps or units is not necessarily limited to the steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products or apparatuses.

[0032] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities may be implemented in software, or in one or more hardware modules or integrated circuits, or in different networks and / or processor devices and / or microcontroller devices. The flowcharts shown in the accompanying drawings are merely exemplary and do not necessarily include all the contents and operations / steps, nor do they necessarily have to be executed in the order described. For example, some operations / steps may be further decomposed, while some operations / steps may be combined or partially combined, so the actual execution order may change according to the actual situation.

[0033] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. In addition, the technical features in the various embodiments or single embodiments provided by the present invention are arbitrarily combined with each other to form a new technical solution. This combination is not restricted by the sequence of steps and / or the structural composition mode, but must be based on the ability of ordinary technicians in this field to achieve. When the combination of technical solutions is contradictory or cannot be achieved, it should be considered that this combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0034] In order to more accurately process the errors in the observation link and establish a gravity potential observation system, the embodiment of the present invention proposes a satellite-to-ground laser time-frequency transfer observation system with a precise error processing module and a gravity potential measurement function. The schematic diagram of the space-to-ground laser link principle of the satellite-to-ground laser time-frequency transfer gravity potential measurement system described in the embodiment of the present invention is shown in FIG. Figure 1 shown.

[0035] See also Figure 2The embodiment of the present invention provides a system for measuring gravity potential by laser time-frequency transmission between satellite and ground, including: an ephemeris preprocessing subsystem for downloading ephemeris and encrypting orbits; a clock error measurement subsystem for receiving observations and calculating clock errors between satellite and ground; a precision error processing subsystem, respectively connected to a coordinate conversion module and a clock error measurement subsystem, for eliminating link errors and evaluating error residuals; a gravity potential conversion subsystem, connected to the precision error processing subsystem, for converting post-processed clock errors into gravity potential errors. In addition, to facilitate data processing, the system provided by the embodiment of the present invention also includes a coordinate conversion module for converting satellite orbit coordinates and ground observation station coordinates from an earth-centered earth-fixed coordinate system to an earth-centered inertial system.

[0036] As a preferred embodiment, the system for measuring gravity potential by laser time-frequency transmission between satellites and the ground provided in the embodiment of the present invention, the ephemeris preprocessing subsystem includes: a network port for downloading satellite (space station) ephemeris in real time, an original ephemeris storage unit for storing original ephemeris data, an orbit encryption module for screening observation epochs of orbit data according to the ground station coordinates and the set ground station cutoff altitude angle and encrypting the screened orbit coordinates, and a post-processing ephemeris storage unit for storing post-processing ephemeris data. Among them, the network port input end is connected to the Internet and the output end is simultaneously connected to the input end of the original ephemeris storage unit and the input end of the orbit encryption module, and the output end of the orbit encryption module is connected to the input end of the post-processing ephemeris storage unit.

[0037] As a preferred embodiment, the system for measuring gravity potential by laser time-frequency transfer between satellites and the ground provided by the embodiment of the present invention, the coordinate conversion module includes: a geocentric earth-fixed coordinate system storage unit for temporarily storing post-processing ephemeris coordinates and ground station coordinates in the geocentric earth-fixed coordinate system, a coordinate conversion algorithm submodule for converting the geocentric earth-fixed coordinate system coordinates into geocentric inertial coordinate system coordinates, and a geocentric inertial coordinate system storage unit for temporarily storing post-processing ephemeris coordinates and ground station coordinates in the geocentric inertial coordinate system. The output end of the geocentric earth-fixed coordinate system storage unit is connected to the input end of the coordinate conversion algorithm submodule, and the output end of the coordinate conversion algorithm submodule is connected to the input end of the geocentric inertial coordinate system storage unit.

[0038] As a preferred embodiment, the system for measuring gravity potential by laser time-frequency transmission between satellite and ground provided by the embodiment of the present invention, the clock error measurement subsystem comprises: a system for transmitting and receiving laser pulse signals and recording the laser pulse signals transmitted by the ground station. and receiving The event timing module at the moment is used to receive the time when the laser pulse arrives at the satellite recorded by the satellite-borne event timing module Communication module for data flow, used to calculate the original clock difference The operation module, Among them, the output ends of the event timing module and the communication module are simultaneously connected to the input end of the operation module.

[0039] Furthermore, the ground station and the satellite are each equipped with an event timing module. The event timing module of the ground station is used to record the time when the ground station laser pulse is emitted and the echo is received, and the event timing module of the satellite is used to record the time when the laser pulse arrives at the satellite.

[0040] As a preferred embodiment, the system for measuring gravity potential by laser time-frequency transmission between satellites and the ground provided in the embodiment of the present invention, the precision error processing subsystem includes: a Sagnac delay correction module for eliminating the Sagnac delay error caused by the rotation of the earth, a tropospheric delay correction module for eliminating the delay error caused by the bending of the laser path and the decrease in propagation speed in the troposphere and evaluating the residual error, a Shapiro delay correction module for eliminating the delay error caused by the bending of the laser propagation path in the gravitational field and evaluating the residual error, and a clock error processing module for eliminating the above-mentioned errors from the original clock error sequence. Among them, the output ends of the three modules of the Sagnac delay correction module, the tropospheric delay correction module, and the Shapiro delay correction module are simultaneously connected to the input end of the clock error processing module.

[0041] The above-mentioned Sagnac delay error correction module and Shapiro delay error correction module both need to complete the calculation through the coordinates of the geocentric inertial coordinate system of the satellite and the ground station output by the coordinate conversion module, and the tropospheric delay correction module needs to complete the calculation through the geocentric earth-fixed coordinate system of the ground station and the satellite.

[0042] Sagnac delay correction:

[0043]

[0044] Shapiro Delay Correction:

[0045] Tropospheric delay correction:

[0046] in, and Respectively in Position vectors of ground station A and satellite S at the moment; is the gravitational constant, for The instantaneous coordinate velocity of satellite S in the geocentric inertial system at time, is the instantaneous acceleration of satellite S; the following parameters of tropospheric delay correction are calculated using the Earth-centered Earth-fixed coordinate system of the ground station and the satellite: is the zenith delayed dry component, is the zenith delayed wet component, is the dry component of the projection function, is the wet component of the projection function.

[0047] As a preferred embodiment, the system for measuring gravity potential by laser time-frequency transfer between satellites and the ground provided in the embodiment of the present invention, the gravity potential conversion subsystem includes: a clock error accuracy assessment module for evaluating the stability of the clock error time series and evaluating whether the expected accuracy is achieved, using Allan deviation to evaluate the clock error stability; a gravity potential calculation module for calculating the clock error time series that meets the accuracy requirements after eliminating errors to obtain gravity potential difference data. Among them, the output end of the accuracy assessment module is connected to the input end of the gravity potential calculation module. It should be noted that in the gravity potential calculation module, meeting the accuracy requirements can be understood as: if the stability reaches the E-18 level within 86400 seconds, it meets the requirements. If it does not meet the requirements, it is necessary to increase the cutoff altitude angle of the observation satellite and increase the observation period until the above-mentioned accuracy requirements are met.

[0048] Specifically, the process of calculating the gravity potential based on the clock difference time series is:

[0049]

[0050] Among them, the left side of the equation is the gravity potential of the ground station, and the first term on the right side of the equation is the differential of the clock error time series with respect to time, is the clock error time series, is a time series, is the speed of light, is the gravitational potential of the satellite, is the instantaneous coordinate velocity of the satellite.

[0051] As a preferred embodiment, the system for measuring gravity potential by laser time-frequency transfer between satellites and the ground provided by the embodiment of the present invention is used to monitor the settlement of satellite laser ranging stations.

[0052] The monitoring objective of this embodiment is to monitor the settlement and deformation of the laser ranging telescope platform to ensure the stability and safety of the platform.

[0053] In order to achieve the above-mentioned monitoring objectives, the embodiment of the present invention uses a satellite-to-ground laser time-frequency transfer system to measure gravity potential. While the satellite laser ranging station conducts routine observations every day, it only needs to observe a satellite equipped with a high-precision atomic clock and laser payload to obtain the daily gravity potential monitoring value of the station.

[0054] The data collection process includes the following steps:

[0055] a. Observation ephemeris preprocessing: convert the target satellite's ephemeris into the observation height and angle of the laser telescope.

[0056] b. Data collection: The telescope transmits laser pulses along the satellite orbit and receives reflected pulses.

[0057] c. Data storage: The collected data is stored in the system's storage unit.

[0058] Based on the data collected above, the daily gravity potential monitoring value of the station is obtained through the satellite-to-ground laser time-frequency transmission measurement gravity potential system, and the gravity potential monitoring value is used to monitor the settlement of the satellite laser ranging station. Compared with the existing settlement monitoring, this embodiment can achieve: (1) monitoring at any time: it can monitor the gravity potential changes and settlement of the laser ranging platform at any time; (2) early warning system: establish an early warning system, and take immediate measures when abnormal changes are found; (3) structural maintenance: timely discovery of structural problems helps to carry out maintenance in advance and extend the life of the laser ranging platform.

[0059] As a preferred embodiment, the system for measuring gravity potential by laser time-frequency transfer between satellites and the ground provided by the embodiment of the present invention is used to conduct earthquake research.

[0060] Earthquakes are the result of the release of energy from the Earth's interior, posing a serious threat to human society and infrastructure. Understanding the patterns of seismic activity and crustal movement is the primary task of seismologists. The Satellite-to-Earth Laser Time-Frequency Transfer Measurement Gravity Potential System is a tool for real-time monitoring of the gravity field of satellite laser ranging stations. It can expand the research direction of laser stations, increase the business functions of laser stations, and provide key data for earthquake research.

[0061] The monitoring objectives of this embodiment are as follows:

[0062] Seismicity: Monitoring the spatial and temporal distribution of earthquakes in order to predict and understand patterns of their occurrence.

[0063] Underground structure: Study underground structure and plate movement by analyzing the underground gravity field.

[0064] Crustal movement: Measure the vertical displacement of the Earth's crust to understand the mechanisms behind earthquake activity.

[0065] In order to achieve the above-mentioned monitoring objectives, an embodiment of the present invention uses a satellite-to-ground laser time-frequency transfer system to measure gravity potential. While the satellite laser ranging station conducts routine observations every day, it observes a satellite equipped with a high-precision atomic clock and laser payload to obtain the daily gravity potential monitoring values ​​of the station.

[0066] The data collection process includes the following steps:

[0067] a. Observation ephemeris preprocessing: convert the target satellite's ephemeris into the observation height and angle of the laser telescope.

[0068] b. Data collection: The telescope transmits laser pulses along the satellite orbit and receives reflected pulses.

[0069] c. Data storage: The collected data is stored in the system's storage unit.

[0070] Based on the data collected above, the daily gravity potential monitoring values ​​of the station are obtained through the satellite-to-ground laser time-frequency transmission measurement gravity potential system, and the gravity potential data are analyzed to obtain key information about seismic activity and crustal movement.

[0071] Specifically, the method for analyzing the gravity position data includes:

[0072] Gravity field analysis: Identify ground gravity field anomalies caused by seismic activity.

[0073] Crustal deformation analysis: Understand the pattern of crustal movement by analyzing the settlement data of the laser ranging platform.

[0074] In the context of earthquake research, the application of the satellite-to-ground laser time-frequency transmission system to measure gravity potential can achieve the following: (1) earthquake activity monitoring: real-time monitoring of earthquake activity and providing data support; (2) underground structure research: in-depth understanding of the characteristics of underground structures and plate movement.

[0075] Based on the same inventive concept as the aforementioned system embodiment, an embodiment of the present invention further provides a method for measuring gravity potential by laser time-frequency transmission between satellites and the ground. By executing this method, the purpose of measuring gravity potential by laser video transmission between satellites and the ground can be achieved.

[0076] See also Figure 3 The method includes: downloading ephemeris and encrypting orbits; receiving observation values ​​and calculating satellite-ground clock errors; eliminating link errors and evaluating error residuals to obtain a clock error time series after eliminating errors; when the clock error time series after eliminating errors reaches the expected accuracy, converting the post-processing clock error into a gravity potential error.

[0077] The method for measuring gravity potential by laser time-frequency transmission between satellites and the ground provided by the embodiment of the present invention is aimed at the current situation that the error of the satellite laser time-frequency transmission link between satellites and the ground is large and it is difficult to meet the centimeter-level precision gravity potential measurement accuracy requirements. Figure 3 Based on the general theory of relativity, the laser time-frequency transfer method is used to obtain the clock difference between the satellite and the ground and calculate the gravity potential of the ground station, so as to measure the gravity potential at the ground station with higher precision.

[0078] Based on the contents of the above method embodiments, as a preferred embodiment, the method for measuring gravity potential by laser time-frequency transfer between satellite and ground provided in the embodiments of the present invention also includes: converting the satellite orbit coordinates and the ground observation station coordinates from the Earth-centered Earth-fixed coordinate system to the Earth-centered inertial system.

[0079] Based on the same inventive concept as the aforementioned embodiment, an embodiment of the present invention further provides a satellite laser ranging station, which is equipped with the above-mentioned system for measuring gravity potential by laser time-frequency transmission between satellite and ground.

[0080] The satellite laser ranging station uses a system for measuring gravity potential using laser time-frequency transmission between the satellite and the ground to quickly process observation data of the current observation arc and obtain the gravity potential at the current station in real time and evaluate the accuracy, thereby measuring the gravity potential at the ground station with higher accuracy.

[0081] Based on the same inventive concept as the aforementioned embodiment, the present invention further provides a non-transitory computer-readable storage medium, wherein the non-transitory computer-readable storage medium stores computer instructions, and the computer instructions enable the computer to execute the method described.

[0082] When the logic instructions of the above modules or steps are implemented in the form of software functional units and sold or used as independent products, they are stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention is essentially or partly in other words, the part that contributes to the prior art or part of the technical solution is embodied in the form of a software product, and the computer software product is stored in a storage medium, including several instructions for a computer device (a personal computer, a server, or a network device) to perform all or part of the steps of the method described in each method embodiment of the present invention. The aforementioned storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a disk or an optical disk, and various media for storing program codes.

[0083] The system embodiments described above are merely illustrative, wherein the units described as separate components are or are not physically separated, and the components shown as units are or are not physical units, located in one place, or distributed on multiple network units. Some or all of the modules are selected according to actual conditions to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art can understand and implement without creative effort.

[0084] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0085] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0086] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0087] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0088] In summary of the above embodiments, the present invention discloses a system and method for measuring gravity potential by laser time-frequency transfer between satellite and ground, which is used to measure the change of gravity potential at a satellite laser ground observation station. The system is composed of an ephemeris preprocessing subsystem, a coordinate conversion module, a clock error measurement subsystem, a precision error processing subsystem, and a gravity potential conversion subsystem, which can quickly process the observation data of the current observation arc segment and obtain the gravity potential at the current station in real time and evaluate the accuracy. The present invention is based on the general theory of relativity and uses the laser time-frequency transfer method to obtain the clock error between satellite and ground and calculate the gravity potential of the ground station. The present invention has opened up a new method for measuring gravity potential by time-frequency transfer, which measures the gravity potential at the ground station with higher accuracy.

[0089] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the technical solutions of the embodiments of the present invention.

Claims

1. A system for measuring gravity potential by laser time-frequency transmission between satellite and ground, characterized in that: include: The ephemeris preprocessing subsystem is used to download the ephemeris and encrypt the orbit; The clock error measurement subsystem is used to receive observations and calculate the clock error between the satellite and the ground; The precision error processing subsystem is connected to the coordinate conversion module and the clock error measurement subsystem respectively, and is used to eliminate the link error and evaluate the error residual amount; the precision error processing subsystem includes: a Sagnac delay correction module, which is used to eliminate the Sagnac delay error caused by the rotation of the earth; a tropospheric delay correction module, which is used to eliminate the delay error caused by the bending of the laser path and the decrease of the propagation speed in the troposphere and evaluate the error residual amount; a Shapiro delay correction module, which is used to eliminate the delay error caused by the bending of the laser propagation path in the gravitational field and evaluate the error residual amount; a clock error processing module, which is used to eliminate the above errors from the original clock error sequence; Sagnac delay correction: ， Shapiro Delay Correction: , Tropospheric delay correction: , in, and Respectively in Position vectors of ground station A and satellite S at the moment; is the gravitational constant, for The instantaneous coordinate velocity of satellite S in the geocentric inertial system at time, is the instantaneous acceleration of satellite S; the following parameters of tropospheric delay correction are calculated using the Earth-centered Earth-fixed coordinate system of the ground station and the satellite: is the zenith delayed dry component, is the zenith delayed wet component, is the projection function dry component, is the wet component of the projection function; The gravity potential conversion subsystem is connected to the precision error processing subsystem and is used to convert the post-processing clock difference into the gravity potential difference.

2. The system for measuring gravity potential by laser time-frequency transfer between satellite and ground according to claim 1 is characterized in that: The system also includes a coordinate conversion module, which is connected to the ephemeris preprocessing subsystem and the precision error processing subsystem respectively, and is used to convert the satellite orbit coordinates and the ground observation station coordinates from the earth-centered earth-fixed coordinate system to the earth-centered inertial system.

3. The system for measuring gravity potential by laser time-frequency transmission between satellite and ground according to claim 1 is characterized in that: The ephemeris preprocessing subsystem includes: a network port for downloading satellite ephemeris in real time; an original ephemeris storage module for storing original ephemeris data; an orbit encryption module for screening the orbit data according to the ground station coordinates and the set ground station cutoff altitude angle, and encrypting the screened orbit coordinates; and a post-processing ephemeris storage module for storing post-processing ephemeris data.

4. The system for measuring gravity potential by laser time-frequency transfer between satellite and ground according to claim 1 is characterized in that: The clock error measurement subsystem includes: an event timing module, which is used to record the emission and echo reception time of the ground station laser pulse, and the time when the laser pulse arrives at the satellite; a communication module, which is used to receive the laser pulse arrival satellite time data stream recorded by the satellite-borne event timing module; and a calculation module, which is used to calculate the original clock error.

5. The system for measuring gravity potential by laser time-frequency transmission between satellite and ground according to claim 1 is characterized in that: The precision error processing subsystem includes: a Sagnac delay correction module, used to eliminate the Sagnac delay error caused by the rotation of the earth; a tropospheric delay correction module, used to eliminate the delay error caused by the bending of the laser path and the decrease in propagation speed in the troposphere and evaluate the error residual; a Shapiro delay correction module, used to eliminate the delay error caused by the bending of the laser propagation path in the gravitational field and evaluate the error residual; a clock error processing module, used to eliminate the above errors from the original clock error sequence.

6. The system for measuring gravity potential by laser time-frequency transfer between satellite and ground according to claim 1 is characterized in that: The gravity potential conversion subsystem includes: a clock error accuracy evaluation module, which is used to evaluate the stability of the clock error time series and whether it reaches the expected accuracy; a gravity potential calculation module, which is used to calculate the clock error time series that meets the accuracy requirements to obtain gravity potential difference data.

7. A method for measuring gravity potential by laser time-frequency transmission between satellite and ground, characterized in that: include: Download ephemeris and encrypt orbits; Receive observations and calculate the satellite-ground clock error; Eliminate link errors and evaluate the residual error to obtain the clock error time series after eliminating the errors, including: eliminating the Sagnac delay error caused by the rotation of the earth, eliminating the delay error caused by the bending of the laser path and the decrease in propagation speed in the troposphere and evaluating the residual error; eliminating the delay error caused by the bending of the laser propagation path in the gravitational field and evaluating the residual error; and eliminating the above errors from the original clock error series; Sagnac delay correction: , Shapiro Delay Correction: , Tropospheric delay correction: , in, and Respectively in Position vectors of ground station A and satellite S at the moment; is the gravitational constant, for The instantaneous coordinate velocity of satellite S in the geocentric inertial system at time, is the instantaneous acceleration of satellite S; the following parameters of tropospheric delay correction are calculated using the Earth-centered Earth-fixed coordinate system of the ground station and the satellite: is the zenith delayed dry component, is the zenith delayed wet component, is the projection function dry component, is the wet component of the projection function; When the clock error time series after error elimination reaches the expected accuracy, the post-processed clock error is converted into gravity potential difference.

8. The method for measuring gravity potential by laser time-frequency transfer between satellite and ground according to claim 7, characterized in that: After downloading the ephemeris and encrypting the orbit, the method further includes: converting the satellite orbit coordinates and the ground observation station coordinates from the Earth-centered Earth-fixed coordinate system to the Earth-centered inertial system.

9. A satellite laser ranging station, characterized in that: A system for measuring gravity potential by using laser time-frequency transmission between satellites and the ground is provided with the system as claimed in any one of claims 1 to 6.

10. A non-transitory computer readable storage medium, characterized in that: The non-transitory computer-readable storage medium stores computer instructions, which cause the computer to execute the method of any one of claims 7 to 8.

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