A method and system for BDS-3 satellite orbit determination and time synchronization

Abstract

The application discloses a Beidou-3 satellite orbit determination and time synchronization method and system. The method comprises the following steps: setting clock difference sampling points at certain intervals in an orbit determination arc segment; in the orbit determination arc segment, orbit determination and time synchronization calculation are performed by using observation values to obtain calculation parameters; theoretical observation values of the observation values are calculated according to the calculation parameters; and residual errors are calculated according to the observation values and the theoretical observation values, and observation values with residual errors exceeding a threshold value are removed. The application directly uses original non-synchronized observation single-pass inter-satellite link data to realize orbit determination and time synchronization, and simultaneously calculates the clock speed parameter of each satellite and the satellite orbit, clock difference, clock speed and other parameters, thereby avoiding the dependence on external satellite clock speed data (such as clock difference rate data in a navigation message), being more rigorous in theory, improving the orbit determination and time synchronization precision, and only adding one clock speed parameter for each satellite, thereby having little influence on the orbit determination and time synchronization calculation efficiency.

Description

Technical Field

[0001] This invention relates to the field of satellite navigation technology, and in particular to a method and system for orbit determination and time synchronization of BeiDou-3 satellites. Background Technology

[0002] China's third-generation BeiDou Navigation Satellite System (BDS-3) is a global navigation satellite system independently designed and constructed by China. The BeiDou-3 system consists of a space segment (24 MEO satellites + 3 GEO satellites + 3 IGSO satellites), a ground segment (including monitoring stations, anchoring stations, master control stations, and injection stations), and a user segment (various types of user receivers). As is known, the master control station of the navigation satellite system collects observation data from the monitoring stations, performs satellite orbit determination and time synchronization, obtains predicted satellite orbit and clock bias information, and injects it into the satellites. The satellites then modulate this information into the downlink navigation signal. The receivers receive the navigation signal broadcast by the satellites, perform pseudorange (and phase) measurements, and demodulate the data to obtain a navigation message containing orbit and clock bias information. The accuracy of the orbit and clock bias information is the main factor affecting the accuracy of user positioning, velocity measurement, and time synchronization. BDS-3 employs inter-satellite link technology. Each satellite is equipped with inter-satellite link equipment, enabling inter-satellite ranging and information transmission in the Ka-band. Satellites can also perform ranging and information transmission with anchored stations (equipped with inter-satellite link equipment). BDS-3's inter-satellite links utilize time-division multiple access (TDMA) for communication and ranging according to a pre-planned schedule, using phased array antennas for signal reception, transmission, and beam pointing control. Within a preset time period, each satellite or anchored station (according to the link establishment plan) sequentially completes communication and ranging with other satellites (there is no link relationship between anchored stations). At any given time slot, only ranging link signals from another satellite or anchored station can be received. For example, within each of the aforementioned time periods, a 3-second time frame is allocated to each pair of satellites (A and B, where either A or B can also be an anchored station). Each satellite uses 1.5 seconds for signal reception and transmission, respectively obtaining two one-way (A->B and B->A) pseudorange observations.

[0003] Inter-satellite link data is crucial for BeiDou-3 satellites to obtain high-precision orbit and clock error information. BeiDou-3 satellites can jointly utilize pseudorange measurement data between satellites (hereinafter referred to as: inter-satellite pseudorange data) and pseudorange (and carrier phase) data in the L-band of ground monitoring stations (hereinafter referred to as: monitoring station data) for orbit determination and time synchronization. Alternatively, they can jointly utilize inter-satellite observation data and Ka pseudorange measurement data between satellites and anchor stations (hereinafter referred to as: anchor station pseudorange data) for orbit determination and time synchronization.

[0004] Inter-satellite pseudorange data and anchor station pseudorange data are characterized by non-simultaneous observations, meaning that the pseudorange observations from each satellite and each anchor station are acquired at different times, resulting in different time scales. The traditional approach is to perform epoch normalization on the data from different times to obtain simultaneous observation data before performing orbit determination and time synchronization. Another approach is to directly utilize the non-simultaneously observed inter-satellite pseudorange data for orbit determination and time synchronization. This method uses piecewise polynomials to describe satellite clock bias, dividing an orbit determination operational arc (e.g., 24 hours) into a series of shorter (e.g., 1 minute) non-overlapping time windows. Within each time window, the satellite or anchor station clock bias is described using a polynomial (e.g., a first-order polynomial). The clock bias parameters to be solved within each time window are a set of polynomial coefficients. To reduce clock bias parameters, known methods include: 1) representing the clock bias of the satellite or anchor station within each time window using a first- or second-order polynomial (corresponding to 2 or 3 clock bias parameters for each satellite within each time window), with the coefficients of the first- or second-order clock bias terms to be calculated being 1 and 2 times the clock bias parameters, respectively. Alternatively, 2) using the clock bias variability and acceleration parameters broadcast in the satellite navigation message to correct the coefficients of the first- and second-order terms. However, in practical applications, in some cases, such as newly launched satellites, there are no broadcast clock velocity parameters available, which increases model error. Summary of the Invention

[0005] Based on this, the present invention provides a method and system for orbit determination and time synchronization of BeiDou-3 satellites.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] A method for orbit determination and time synchronization of BeiDou-3 satellites includes:

[0008] Within the orbit determination arc, orbit determination and time synchronization calculations are performed using observations to obtain calculation parameters; the orbit determination arc is equipped with clock error sampling points at certain intervals; the calculation parameters include: orbital parameters of each satellite, clock error parameters of each satellite, and clock speed parameters of each satellite.

[0009] Calculate the theoretical observed value of the observed value based on the solution parameters;

[0010] The residuals are calculated based on the observed values ​​and the theoretical observed values, and observed values ​​whose residuals exceed a threshold are discarded.

[0011] Optionally, within the orbit determination arc, orbit determination and time synchronization calculations are performed using observations to obtain calculation parameters, specifically including:

[0012] By performing orbit integration using the initial orbit information, a reference orbit, state transition matrix, and sensitivity matrix sampled at certain time intervals are obtained;

[0013] The observation equations are linearized based on the reference orbit, the state transition matrix, and the sensitivity matrix; the observation equations are either observation equations based on inter-satellite pseudorange data / anchor station pseudorange data or joint observation equations based on inter-satellite pseudorange data and monitoring station data.

[0014] The linear optimal estimation method is used to solve the linearized observation equations to obtain the solution parameters.

[0015] Optionally, the observed values ​​include inter-satellite pseudorange data and anchor station pseudorange data; the theoretical observed values ​​include theoretical observed values ​​of inter-satellite pseudorange data and theoretical observed values ​​of anchor station pseudorange data.

[0016] Optionally, the observed values ​​include inter-satellite pseudorange data and monitoring station data; the theoretical observed values ​​include theoretical observed values ​​of inter-satellite pseudorange data and theoretical observed values ​​of monitoring station data.

[0017] This invention also provides a BeiDou-3 satellite orbit determination and time synchronization system, comprising:

[0018] The orbit determination module is used to perform orbit determination and time synchronization calculations using observations within the orbit determination arc to obtain calculation parameters. The orbit determination arc is equipped with clock difference sampling points at certain intervals. The calculation parameters include: orbital parameters of each satellite, clock difference parameters of each satellite, and clock speed parameters of each satellite.

[0019] The theoretical observation calculation module is used to calculate the theoretical observation value of the observation value based on the solution parameters;

[0020] The residual calculation and elimination module is used to calculate the residual based on the observed value and the theoretical observed value, and to eliminate observed values ​​whose residual exceeds a threshold.

[0021] This invention also provides a method for orbit determination and time synchronization of BeiDou-3 satellites, comprising:

[0022] Within the orbit determination arc, orbit determination and time synchronization calculations are performed using observations to obtain calculation parameters; the orbit determination arc is equipped with clock error sampling points at certain intervals; the calculation parameters include: orbital parameters of each satellite and clock error parameters of each satellite.

[0023] Calculate the posterior residuals of the observed values ​​based on the solution parameters;

[0024] The clock rate is calculated based on the a posteriori residuals.

[0025] The observed value is corrected based on the clock speed;

[0026] Based on the corrected observations, orbit determination and time synchronization were recalculated to obtain the recalculated parameters.

[0027] Calculate the theoretical observed value of the observed value based on the recalculated parameters;

[0028] The residuals are calculated based on the observed values ​​and the theoretical observed values, and observed values ​​whose residuals exceed a threshold are discarded.

[0029] Optionally, within the orbit determination arc, orbit determination and time synchronization calculations are performed using observations to obtain calculation parameters, specifically including:

[0030] By performing orbit integration using the initial orbit information, a reference orbit, state transition matrix, and sensitivity matrix sampled at certain time intervals are obtained;

[0031] The observation equations are linearized based on the reference orbit, the state transition matrix, and the sensitivity matrix; the observation equations are either observation equations based on inter-satellite pseudorange data / anchor station pseudorange data or joint observation equations based on inter-satellite pseudorange data and monitoring station data.

[0032] The linear optimal estimation method is used to solve the linearized observation equations to obtain the solution parameters.

[0033] Optionally, the observations include inter-satellite pseudorange data and anchor station pseudorange data; the posterior residuals include the posterior residuals of the inter-satellite pseudorange data and the posterior residuals of the anchor station pseudorange data; and the clock speeds include satellite clock speeds and anchor station clock speeds.

[0034] Optionally, the observations include inter-satellite pseudorange data and monitoring station data; the posterior residuals include the posterior residuals of the inter-satellite pseudorange data; and the clock speeds include satellite clock speeds.

[0035] This invention also provides a BeiDou-3 satellite orbit determination and time synchronization system, comprising:

[0036] The orbit determination module is used to perform orbit determination and time synchronization calculations using observations within the orbit determination arc to obtain calculation parameters; the orbit determination arc is set with clock difference sampling points at certain intervals; the calculation parameters include: orbital parameters of each satellite and clock difference parameters of each satellite;

[0037] The posterior residual calculation module calculates the posterior residuals of the observed values ​​based on the solution parameters.

[0038] The clock speed calculation module is used to calculate the clock speed based on the posterior residual;

[0039] The correction module is used to correct the observed value according to the clock speed;

[0040] The recalculation module is used to recalculate orbit determination and time synchronization based on the corrected observations, and obtain the recalculated parameters.

[0041] The theoretical observation calculation module is used to calculate the theoretical observation value of the observation value based on the recalculated parameters.

[0042] The residual calculation and elimination module is used to calculate the residual based on the observed value and the theoretical observed value, and to eliminate observed values ​​whose residual exceeds a threshold.

[0043] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0044] The first method for orbit determination and time synchronization of BeiDou-3 satellites provided by this invention directly utilizes the original asynchronous observation data from one-way inter-satellite links to achieve orbit determination and time synchronization. By solving the clock velocity parameters of each satellite along with parameters such as satellite orbit and clock bias, it avoids dependence on external satellite clock velocity data (such as clock bias rate data of navigation messages), which is theoretically more rigorous and can improve the accuracy of orbit determination and time synchronization. At the same time, each satellite only adds one clock velocity parameter, which has a minimal impact on the efficiency of orbit determination and time synchronization calculation.

[0045] The second method for orbit determination and time synchronization of BeiDou-3 satellites provided by this invention calculates the satellite clock rate of each satellite through a posteriori residuals and corrects the original observations by clock rate, thereby eliminating the influence of satellite clock error changes on inter-satellite or anchor station pseudorange observations at different times. This avoids calculating satellite clock rate parameters at the same time as calculating orbit parameters, and also avoids dependence on external satellite clock rate data (such as clock error rate data of navigation messages). Attached Figure Description

[0046] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0047] Figure 1 A flowchart of the BeiDou-3 satellite orbit determination and time synchronization method provided in Embodiment 1 of the present invention;

[0048] Figure 2 This is a flowchart of the BeiDou-3 satellite orbit determination and time synchronization method provided in Embodiment 3 of the present invention. Detailed Implementation

[0049] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0050] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0051] Example 1

[0052] like Figure 1 As shown in the figure, this embodiment provides a method for orbit determination and time synchronization of a BeiDou-3 satellite, which includes the following steps:

[0053] Step 101: Within the orbit determination arc, orbit determination and time synchronization are calculated using observations to obtain solution parameters. These parameters include the orbital parameters, clock bias parameters, and clock velocity parameters of each satellite. Specifically, this involves: performing orbit integration using initial orbital information to obtain a reference orbit, state transition matrix, and sensitivity matrix sampled at certain time intervals; linearizing the observation equations based on the reference orbit, state transition matrix, and sensitivity matrix; the observation equations are either inter-satellite pseudorange data / anchor station pseudorange data observation equations or joint observation equations of inter-satellite pseudorange data and monitoring station data; and solving the linearized observation equations using a linear optimal estimation method to obtain solution parameters.

[0054] Step 102: Calculate the theoretical observation value of the observation value based on the solution parameters.

[0055] Step 103: Calculate the residuals based on the observed values ​​and the theoretical observed values, and remove observed values ​​whose residuals exceed the threshold.

[0056] In this embodiment, the observed values ​​can be inter-satellite pseudorange data combined with anchor station pseudorange data, or inter-satellite pseudorange data combined with monitoring station data.

[0057] In this embodiment, orbit determination and time synchronization are achieved directly using the original asynchronous observation one-way inter-satellite link data. By solving the clock speed parameters of each satellite along with satellite orbit, clock bias, and other parameters, the reliance on external satellite clock speed data (such as clock bias rate data of navigation messages) is avoided, which is theoretically more rigorous and can improve the accuracy of orbit determination and time synchronization. At the same time, only one clock speed parameter is added to each satellite, which has little impact on the efficiency of orbit determination and time synchronization calculation.

[0058] (I) When inter-satellite pseudorange data is combined with anchor station pseudorange data, a specific implementation case is used to elaborate on the technical solution and effects of the method of the present invention. In this example, orbit determination and time synchronization calculations are performed using inter-satellite pseudorange data and anchor station pseudorange data of 24-hour arc length from 4 anchor stations and 30 BDS-3 satellites. Data processing includes the following steps:

[0059] Step 1: Set clock difference sampling points: Set a clock difference sampling point every 10 minutes. The clock difference sampling times are: 00:00:00, 00:10:00, ..., 23:50:00.

[0060] Step 2: Orbit Determination and Time Synchronization Calculation: Orbit determination and time synchronization calculations are performed using inter-satellite pseudorange data combined with anchor station observation data. The observation equations for inter-satellite or anchor station pseudorange data are as follows:

[0061]

[0062] In this context, the superscripts i and j represent satellites or anchor stations, where 1 ≤ i, j ≤ 30 represents a satellite and 31 ≤ i, j ≤ 34 represents an anchor station. P i,j For t i,j At time τ, satellite i observes pseudorange observations from satellite j (one of which can be an anchored station, but not both can be anchored stations simultaneously); i,j R represents the time it takes for the signal to propagate. * (*=i,j) is the position vector of the satellite or anchorage station*. Distance time t for satellite or anchored station* i,j Clock difference parameters from the most recent clock difference sampling point; υ * (*=i,j) represents the clock speed parameter of the satellite or anchor station; Represents the observation time and the most recent clock difference sampling time t k The time difference. The formula omits correction terms for transceiver delay, antenna phase center deviation, and general relativistic delay.

[0063] The specific steps of orbit determination and time synchronization processing include:

[0064] (1) Orbit Integration: Orbit integration is performed using the initial orbit information to obtain the reference orbit, state transition matrix, and sensitivity matrix sampled at 15-minute intervals. This process uses the Adams-Bashforth-Moulton method for numerical integration. The satellite's dynamic model is as follows: the Earth's gravitational field (12th-order EGM2008 model), the changes caused by solid tides and ocean tides, the gravitational forces of the third body generated by the Sun, Moon, and planets, and the solar radiation pressure perturbation force are all represented by a 5-parameter ECOM model {D0,Y0,B0,B...}. s B c The post-Newtonian effect is corrected using a model.

[0065] (2) Linearization of the observation equations: When calculating theoretical observation values, the general relativistic gravitational delay is corrected using a model; the centroid deviation of the receiving and transmitting antennas is corrected using values ​​provided by the manufacturer; the relativistic periodicity of the satellite clock is corrected using a model; and the time delay of the receiving and transmitting equipment is corrected using calibration values. The tropospheric zenith delay of the anchoring station is calculated using the Saastamoinen model, with GMF as the mapping function. Displacements caused by solid tides, ocean tidal loads, and polar tides are corrected according to the IERS2010 standard. Unknown parameters include the initial position, velocity vector, solar radiation pressure model parameters, clock velocity parameters of the satellite and anchoring station, clock difference parameters of the satellite and anchoring station at each clock difference sampling point, and the hourly tropospheric zenith delay parameter of each anchoring station.

[0066] (3) Parameter Solution: The unknown parameters are solved using the least squares method. The solved parameters include the orbital parameters of each satellite (initial state vector and solar radiation pressure model coefficients {D0, Y0, B0, B...}). s B c The parameters include the clock rate parameters for each satellite and each anchor station, the clock difference parameters for each satellite and anchor station at every full ten-minute interval, and the tropospheric zenith delay parameter for each anchor station per hour. The clock difference of the first anchor station (numbered 31) is constrained to be 0, and the sum of the clock rates of all satellites and anchor stations is constrained to be 0. Therefore, the constraint equations for the observation equations are expressed as follows:

[0067]

[0068] Where, p θ Here, p represents the weights of the clock constraint equations. θ =10 16 ;p υ Here, p can be taken as the weight of the clock speed constraint equation. υ =10 10 .

[0069] Step 3, Gross Error Detection: Using the solution results of unknown parameters such as orbit, clock error, and clock speed obtained in Step 2, calculate the theoretical observation value for each observation, and then obtain the residual for each observation. Data with residuals exceeding a certain limit are discarded. The condition for exceeding the limit is that the absolute value of the residual exceeds 5·σ.

[0070] The theoretical observation values ​​calculated using the results of step two

[0071]

[0072] in, The theoretical observation values ​​are calculated using the results of step two; The t calculated using the orbital parameters obtained in step two i,j The position of satellite i at any given time; The t calculated using the orbital parameters obtained in step two i,j -τ i,j The position of satellite j at any given time; and These are the clock error calculation values ​​for satellites i and j corresponding to clock error sampling point k, respectively; and These are the clock speed calculation values ​​for stars i and j, respectively. The formula omits correction terms for inter-satellite link transceiver delay, antenna phase center deviation, and general relativistic delay.

[0073] Calculate residual V i,j (t i,j ):

[0074] V i,j (t i,j ) represents the corresponding observation value P i,j (t i,j The residual of ).

[0075] Determine if the residual exceeds the limit:

[0076] The specific conditions are: |V i,j (t i,j )|>m·σ

[0077] Where m is the set threshold value, usually a value greater than 3, here m = 5, and σ represents the residual V. i,j (t i,j The statistical values ​​of σ are calculated separately for inter-satellite pseudorange data and anchor station pseudorange data. σ can be calculated using the following formula:

[0078]

[0079] Among them, W i,j (t i,j ) is the corresponding V i,j (t i,j If a residual exceeds the limit, it indicates that the corresponding observation has gross errors, and the data is discarded. That is, the data will no longer be used in subsequent orbit determination and time synchronization calculations.

[0080] Repeat steps two and three until the convergence condition is met: the number of iterations exceeds 10 or no new gross errors are found.

[0081] The above embodiments demonstrate the use of this scheme to directly utilize raw inter-satellite pseudorange data combined with anchor station pseudorange data for BeiDou-3 satellite orbit determination and time synchronization. During orbit determination and time synchronization calculations, it is not necessary to correct the observation data using broadcast clock rate parameters, nor is it necessary to perform epoch normalization on the observation data.

[0082] (II) When combining inter-satellite pseudorange data with monitoring station data, another specific implementation example is used to elaborate on the technical solution and effects of the method of the present invention. In this example, inter-satellite pseudorange data of 24-hour arc length from 30 BDS-3 satellites and carrier phase and pseudorange observation data from 30 monitoring stations are used for orbit determination and time synchronization, wherein the data sampling interval of the monitoring stations is 1 minute. Data processing includes the following steps:

[0083] Step 1: Set clock difference sampling points: For the sampling time of the data from the corresponding monitoring station, set a clock difference sampling point every 1 minute. The clock difference sampling times are: 00:00:00, 00:01:00, ..., 23:59:00.

[0084] Step 2: Orbit Determination and Time Synchronization Calculation: Orbit determination and time synchronization calculations are performed using inter-satellite pseudorange data combined with monitoring station observation data. The joint observation equations are as follows:

[0085]

[0086]

[0087]

[0088] Among them, P i,j For t i,j At time τ, satellite i observes pseudorange observations of satellite j; i,j R represents the time it takes for the signal to propagate. i and R j Let be the position vectors of satellite i and satellite j, respectively. Let the distance t be... i,j The most recent clock bias sampling point is k, and the corresponding clock biases of the two satellites are respectively and t k The time of the kth clock difference sampling point is also the observation time of the kth epoch of the ground monitoring station data; Indicates the propagation time of the signal from the satellite to the station; and Let ε and ξ represent the ionospheric carrier phase and pseudorange observations of satellite i as observed by station r, respectively, and let ε and ξ represent the corresponding measurement errors. R represents tropospheric delay. r Indicates the location of the measuring station, θ r,k υ represents the clock difference of station r at the k-th sampling point;i and υ j These are the clock speed parameters for satellite i and satellite j, respectively; Represents the observation time and the most recent clock difference sampling time t k Time difference; This represents the ambiguity parameter. The formula omits correction terms for inter-satellite link transceiver delay, antenna phase center deviation, general relativistic delay, and phase entanglement effects of carrier phase data.

[0089] The specific steps of orbit determination and time synchronization processing include:

[0090] (1) Orbit Integration: Orbit integration is performed using the initial orbit information to obtain the reference orbit, state transition matrix, and sensitivity matrix sampled every 15 minutes. This process uses the Adams-Bashforth-Moulton method for numerical integration. The satellite force model considers the Earth's gravitational field (12th-order EGM2008 model), the changes caused by solid tides and ocean tides, the gravitational forces of the Sun, Moon, and planets, and the solar radiation pressure perturbation force, using a 5-parameter ECOM model {D0,Y0,B0,B...}. s B c The post-Newtonian effect is corrected using a model.

[0091] (2) Linearization of the observation equations: When calculating theoretical observation values, the general relativistic gravitational delay is corrected using a model; the centroid deviation of the inter-satellite link receiving and transmitting antennas is corrected using values ​​provided by the manufacturer; the relativistic periodicity of the satellite clock is corrected using a model; and the delay of the receiving and transmitting equipment is corrected using calibration values. The tropospheric zenith delay of the station is calculated using the Saastamoinen model, with GMF as the mapping function. The displacement caused by solid tides, ocean tidal loads, and polar tides is corrected according to the IERS2010 standard. The PCO and PCV of the navigation signal transmitting and receiving antennas are based on the manufacturer's calibration values. Unknown parameters include the initial position, velocity vector, solar radiation pressure model parameters, satellite clock velocity parameters, satellite and station clock difference parameters at each sampling point, and the tropospheric zenith delay parameters for each station per hour.

[0092] (3) Parameter Solution. The least squares method is used to solve for the unknown parameters. The solved parameters include the orbital parameters of each satellite (initial state vector and solar radiation pressure model coefficients {D0, Y0, B0, B...}). s B cThe parameters include the clock rate of each satellite, the clock difference between the satellite and the monitoring station at every full ten-minute interval, the tropospheric zenith delay parameter for each monitoring station per hour, and the ambiguity parameter for each continuous cycle-slip-free carrier phase tracking arc for each satellite at each station. The clock difference of the first monitoring station (numbered 1) is constrained to be 0, and the sum of the clock rate parameters of all satellites is constrained to be 0. Therefore, the constraint equations for the observation equations are expressed as follows:

[0093]

[0094] Where, p θ Here, p represents the weights of the clock constraint equations. θ =10 16 ;p υ Here, p can be taken as the weight of the clock speed constraint equation. υ =10 10 .

[0095] Step 3: Gross Error Detection. Using the solution results of unknown parameters such as orbit, clock error, and clock speed obtained in Step 2, calculate the theoretical observation value for each observation quantity, and then obtain the residual for each observation value. Data with residuals exceeding a certain limit are discarded. The condition for exceeding the limit is that the absolute value of the residual exceeds 5·σ. σ is statistically analyzed for both inter-satellite pseudorange data and monitoring station data (including monitoring station pseudorange data and monitoring station carrier phase data).

[0096] The formula for calculating theoretical observations is as follows:

[0097]

[0098]

[0099]

[0100] in, The theoretical observation values ​​of the inter-satellite pseudorange data obtained using the results of step two; The t is calculated using the orbital parameters obtained from the results of step two. i,j The position of satellite i at any given time; The t is calculated using the orbital parameters obtained from the results of step two. i,j -τ i,j The position of satellite j at any given time; and These are the clock error calculation values ​​for satellites i and j corresponding to clock error sampling point k, respectively; and These are the clock velocity solutions for stars i and j, respectively. and These are the theoretical observation values ​​of the ionospheric carrier phase and pseudorange data of satellite i obtained from station r using the results of step two. This indicates the tropospheric delay obtained using the results of step two. This indicates the station obtained in step two. r The clock difference at the k-th sampling point; This represents the ambiguity parameter solution value obtained in step two. The formula omits correction terms for inter-satellite link transceiver delay, antenna phase center deviation, general relativistic delay, and phase entanglement effects of carrier phase data.

[0101] The residual calculation formulas for the three types of observations are as follows:

[0102]

[0103]

[0104]

[0105] Among them, V i,j (t i,j ), and The corresponding observations P i,j (t i,j ), and The residual.

[0106] The corresponding statistical calculation formulas are as follows:

[0107]

[0108]

[0109]

[0110] W i,j (t i,j ), and They are respectively the corresponding V i,j (t i,j ), and The weights; N, N L and N P The corresponding observations P i,j (t i,j ), and The number of.

[0111] Repeat steps two and three until the convergence condition is met: the number of iterations exceeds 10 or no new gross errors are found.

[0112] Example 2

[0113] In order to implement the method corresponding to Embodiment 1 above and achieve the corresponding functions and technical effects, a BeiDou-3 satellite orbit determination and time synchronization system is provided below.

[0114] The system includes:

[0115] The orbit determination module is used to perform orbit determination and time synchronization calculations using observations within the orbit determination arc to obtain calculation parameters. The orbit determination arc is equipped with clock difference sampling points at certain intervals. The calculation parameters include: orbital parameters of each satellite, clock difference parameters of each satellite, and clock speed parameters of each satellite.

[0116] The theoretical observation calculation module is used to calculate the theoretical observation value of the observation value based on the solution parameters;

[0117] The residual calculation and elimination module is used to calculate the residual based on the observed value and the theoretical observed value, and to eliminate observed values ​​whose residual exceeds a threshold.

[0118] Example 3

[0119] like Figure 2 As shown in the figure, this embodiment provides a method for orbit determination and time synchronization of a BeiDou-3 satellite, which includes the following steps:

[0120] Step 201: Within the orbit determination arc, orbit determination and time synchronization calculations are performed using observations to obtain calculation parameters. These parameters include the orbital parameters and clock bias parameters of each satellite. Specifically, this includes: performing orbit integration using initial orbital information to obtain a reference orbit, state transition matrix, and sensitivity matrix sampled at certain time intervals; linearizing the observation equations based on the reference orbit, state transition matrix, and sensitivity matrix; the observation equations are either inter-satellite pseudorange data / anchor station pseudorange data observation equations or joint observation equations of inter-satellite pseudorange data and monitoring station data; and solving the linearized observation equations using a linear optimal estimation method to obtain the calculation parameters.

[0121] Step 202: Calculate the posterior residuals of the observations based on the solution parameters.

[0122] Step 203: Calculate the clock rate based on the a posteriori residual.

[0123] Step 204: Correct the observed value according to the clock speed.

[0124] Step 205: Recalculate the orbit determination and time synchronization based on the corrected observations to obtain the recalculated parameters.

[0125] Step 206: Calculate the theoretical observation value of the observation value based on the recalculated parameters.

[0126] Step 207: Calculate the residuals based on the observed values ​​and the theoretical observed values, and remove observed values ​​whose residuals exceed the threshold.

[0127] In this embodiment, the observed values ​​can be inter-satellite pseudorange data combined with anchor station pseudorange data, or inter-satellite pseudorange data combined with monitoring station data.

[0128] In this embodiment, the satellite clock velocity of each satellite is calculated using posterior residuals, and clock velocity correction is applied to the original observations to eliminate the influence of satellite clock bias variations on inter-satellite pseudorange observations at different times. This invention avoids calculating satellite clock velocity parameters simultaneously with orbital parameters and also avoids dependence on external satellite clock velocity data (such as clock bias variability data from navigation messages). In practical applications, modules for calculating satellite clock velocities using residuals and correcting observations for clock velocities can be added directly to traditional navigation satellite orbit determination data processing software, facilitating software programming implementation.

[0129] (I) When inter-satellite pseudorange data is combined with anchor station pseudorange data, a specific implementation case is used to elaborate on the technical solution and effects of the method of the present invention. In this example, orbit determination and time synchronization calculations are performed using inter-satellite pseudorange data and anchor station pseudorange data of 24-hour arc length from 4 anchor stations and 30 BDS-3 satellites. Data processing includes the following steps:

[0130] Step 1: Set clock difference sampling points: Set a clock difference sampling point every 10 minutes. The clock difference sampling times are: 00:00:00, 00:10:00, ..., 23:50:00.

[0131] Step 2: Orbit Determination and Time Synchronization Calculation: Orbit determination and time synchronization calculations are performed using inter-satellite pseudorange data combined with anchor station observation data. The observation equations for inter-satellite or anchor station pseudorange data are as follows:

[0132]

[0133] In this context, the superscripts i and j represent satellites or anchor stations, where 1 ≤ i, j ≤30 Describing a satellite, 31≤i,j ≤34 Indicates the anchorage station. P i,j For t i,j At time τ, satellite i observes pseudorange observations from satellite j (one of which can be an anchored station, but not both can be anchored stations simultaneously); i,j R represents the time it takes for the signal to propagate. * (*=i,j) is the position vector of the satellite or anchorage station*. Let t be the distance from time t i,jThe clock bias parameters of the satellite or anchor station* at the nearest clock bias sampling point k. The formula omits correction terms for transceiver delay, antenna phase center deviation, and general relativistic delay.

[0134] The specific steps of orbit determination and time synchronization processing include:

[0135] (1) Orbit Integration: Orbit integration is performed using the initial orbit information to obtain the reference orbit, state transition matrix, and sensitivity matrix sampled at 15-minute intervals. This process uses the Adams-Bashforth-Moulton method for numerical integration. The satellite's dynamic model is as follows: the Earth's gravitational field (12th-order EGM2008 model), the changes caused by solid tides and ocean tides, the gravitational forces of the third body generated by the Sun, Moon, and planets, and the solar radiation pressure perturbation force are all represented by a 5-parameter ECOM model {D0,Y0,B0,B...}. s B c The post-Newtonian effect is corrected using a model.

[0136] (2) Linearization of the observation equations: When calculating theoretical observation values, the general relativistic gravitational delay is corrected using a model; the centroid deviation of the receiving and transmitting antennas is corrected using values ​​provided by the manufacturer; the relativistic periodicity of the satellite clock is corrected using a model; and the time delay of the receiving and transmitting equipment is corrected using calibration values. The tropospheric zenith delay of the anchoring station is calculated using the Saastamoinen model, with GMF as the mapping function. Displacements caused by solid tides, ocean tidal loads, and polar tides are corrected according to the IERS2010 standard. Unknown parameters include the initial position, velocity vector, and solar radiation pressure model parameters of each satellite; the clock difference parameters of the satellite and anchoring station at each clock difference sampling point; and the hourly tropospheric zenith delay parameters of each anchoring station.

[0137] (3) Parameter Solution: The unknown parameters are solved using the least squares method. The solved parameters include the orbital parameters of each satellite (initial state vector and solar radiation pressure model coefficients {D0, Y0, B0, B...}). s B c The clock bias parameters for the satellite and anchor stations at every full ten-minute interval, and the tropospheric zenith delay parameter for each anchor station per hour. The clock bias of the first anchor station (numbered 31) is constrained to be 0. Therefore, the constraint equations for the observation equations are expressed as follows:

[0138]

[0139] Where, p θ Here, p is taken as the weight of the constraint equation. θ =10 16 .

[0140] Step 3: Calculate Clock Rates: Using the posterior residuals of the inter-satellite and anchor station pseudorange data obtained from the previous orbit determination calculation, calculate the clock rates of the satellite and anchor stations. The formula is as follows:

[0141]

[0142] Where, ΔP i,j (t i,j ) indicates correspondence The posterior residuals; This indicates the pseudorange observations from inter-satellite or anchored stations used in the previous orbit determination; Clock speed parameters for satellites or anchor stations*; It represents the time difference between the observation time and the most recent clock difference sampling time.

[0143] The least squares method was used for the solution, where the clock velocity of satellite 1 was constrained to 0.

[0144] Step 4: Clock Rate Correction: Perform clock rate correction on the inter-satellite and anchor station pseudorange data. The formula is as follows:

[0145]

[0146] in, This represents the pseudorange data between satellites or anchored stations after clock speed correction; This indicates the pseudorange observations from inter-satellite or anchored stations used in the previous orbit determination; These are the clock speed parameters for the satellite or anchor station* obtained in step three.

[0147] Step 5: Orbit Determination and Time Synchronization Calculation: Using the clock-corrected observation data as the measurement, the orbit determination and time synchronization calculation are performed again using the method from Step 2. The observation equations for orbit determination at this point are as follows:

[0148]

[0149] Step Six: Gross Error Detection. Using the solution results of unknown parameters such as orbit and clock error obtained in Step Five, calculate the theoretical observation value for each observation quantity, and then obtain the residual for each observation value. Data with residuals exceeding a certain limit are discarded. The condition for exceeding the limit is that the absolute value of the residual exceeds 5·σ.

[0150] The theoretical observation value is calculated using the results from step five.

[0151]

[0152] in, The t calculated using the orbital parameters obtained in step five i,j The position of satellite i at any given time; The t calculated using the orbital parameters obtained in step five i,j -τ i,j The position of satellite j at any given time; and These are the clock error calculation values ​​for satellites i and j corresponding to clock error sampling point k (either i or j can be an anchor station).

[0153] Corresponding observations residual V i,j (t i,j The following formula can be used to calculate:

[0154]

[0155] The specific conditions for determining that the residual exceeds the limit are:

[0156]

[0157] Where m is the set threshold value, usually greater than 3, and σ represents the residual V. i,j (t i,j The statistical value of ) can be calculated, for example, by the following formula:

[0158]

[0159] Among them, W i,j (t i,j ) represents the corresponding observation. The weights.

[0160] Repeat steps three through six until the convergence condition is met.

[0161] The above embodiments demonstrate the use of this scheme to directly utilize raw inter-satellite and anchor station pseudorange data for BeiDou-3 satellite orbit determination and time synchronization. This avoids calculating clock difference polynomial coefficients during orbit determination and time synchronization, and eliminates the need to correct observation data using broadcast clock rate parameters. Furthermore, it eliminates the need for epoch normalization of the observation data.

[0162] (II) When combining inter-satellite pseudorange data with monitoring station data, another specific implementation example is used to elaborate on the technical solution and effects of the method of the present invention. In this example, inter-satellite pseudorange data of 24-hour arc length from 30 BDS-3 satellites and carrier phase and pseudorange observation data from 30 monitoring stations are used for orbit determination and time synchronization, wherein the data sampling interval of the monitoring stations is 1 minute. Data processing includes the following steps:

[0163] Step 1: Set clock difference sampling points: For the sampling time of the data from the corresponding monitoring station, set a clock difference sampling point every 1 minute. The clock difference sampling times are: 00:00:00, 00:01:00, ..., 23:59:00.

[0164] Step 2: Orbit Determination and Time Synchronization Calculation: Orbit determination and time synchronization calculations are performed using inter-satellite pseudorange data combined with monitoring station observation data. The joint observation equations are as follows:

[0165]

[0166]

[0167]

[0168] Among them, P i,j For t i,j At time τ, satellite i observes pseudorange observations of satellite j; i,j R represents the time it takes for the signal to propagate. i and R j Let be the position vectors of satellite i and satellite j, respectively. Let the distance t be... i,j The most recent clock bias sampling point is k, and the corresponding clock biases of the two satellites are respectively and t k The time of the kth clock difference sampling point is also the observation time of the kth epoch of the ground monitoring station data; Indicates the propagation time of the signal from the satellite to the station; and Let ε and ξ represent the ionospheric carrier phase and pseudorange observations of satellite i as observed by station r, respectively, and let ε and ξ represent the corresponding measurement errors. R represents tropospheric delay. r Indicates the location of the measuring station, θ r,k Indicates the station r The clock difference at the k-th sampling point This represents the carrier phase ambiguity parameter of station r for satellite i. The formula omits correction terms for inter-satellite link transceiver delay, antenna phase center deviation, general relativistic delay, and phase entanglement effects of carrier phase data.

[0169] The specific steps of orbit determination and time synchronization processing include:

[0170] (1) Orbit Integration: Orbit integration is performed using the initial orbit information to obtain the reference orbit, state transition matrix, and sensitivity matrix sampled every 15 minutes. This process uses the Adams-Bashforth-Moulton method for numerical integration. The satellite force model considers the Earth's gravitational field (12th-order EGM2008 model), the changes caused by solid tides and ocean tides, the gravitational forces of the Sun, Moon, and planets, and the solar radiation pressure perturbation force, using a 5-parameter ECOM model {D0,Y0,B0,B...}. s B c The post-Newtonian effect is corrected using a model.

[0171] (2) Linearization of the observation equations: When calculating theoretical observation values, the general relativistic gravitational delay is corrected using a model; the centroid deviation of the inter-satellite link receiving and transmitting antennas is corrected using values ​​provided by the manufacturer; the relativistic periodicity of the satellite clock is corrected using a model; and the delay of the receiving and transmitting equipment is corrected using calibration values. The tropospheric zenith delay of the station is calculated using the Saastamoinen model, with GMF as the mapping function. The displacement caused by solid tides, ocean tidal loads, and polar tides is corrected according to the IERS2010 standard. The PCO and PCV of the navigation signal transmitting and receiving antennas are based on the manufacturer's calibration values. Unknown parameters include the initial position, velocity vector, and solar radiation pressure model parameters of each satellite; the clock difference parameters of the satellite and station at each sampling point; the tropospheric zenith delay parameters of each station per hour; and the ambiguity parameters of each station for each satellite's continuous cycle-slip-free carrier phase tracking arc.

[0172] (3) Parameter Solution: The unknown parameters are solved using the least squares method. The solved parameters include the orbital parameters of each satellite (initial state vector and solar radiation pressure model coefficients {D0, Y0, B0, B...}). s B c The parameters include the clock bias parameters of the satellite and monitoring station at each whole minute, the tropospheric zenith delay parameter for each monitoring station per hour, and the ambiguity parameter for each station's tracking arc of each continuous cycle-slip-free carrier phase for each satellite. The clock bias of the first monitoring station (numbered 1) is constrained to be 0. Therefore, the constraint equations for the observation equations are as follows:

[0173] θ 1,k =0……p θ (k = 1, 2, ... 1440)

[0174] Where, p θ Here, p is taken as the weight of the constraint equation. θ =10 16 .

[0175] Step 3: Calculate the clock velocity: Calculate the satellite's clock velocity using the posterior residuals of the inter-satellite pseudorange data obtained from the previous orbit determination. The formula is as follows:

[0176]

[0177] Where, ΔP i,j (t i,j ) indicates correspondence The posterior residuals; This represents the inter-satellite pseudorange observations used in the previous orbit determination; For the clock speed parameters of the satellite*; It represents the time difference between the observation time and the most recent clock difference sampling time.

[0178] The least squares method was used for the solution, where the clock velocity of satellite 1 was constrained to 0.

[0179] Step 4: Clock Rate Correction: Perform clock rate correction on the inter-satellite pseudorange data. The formula is as follows:

[0180]

[0181] in, This represents the inter-satellite pseudorange data after clock speed correction; This represents the inter-satellite pseudorange observations used in the previous orbit determination; These are the satellite clock speed parameters obtained in step three.

[0182] Step 5: Orbit Determination and Time Synchronization Calculation: Using the clock-corrected inter-satellite pseudorange observation data, combined with the carrier phase and pseudorange data from the monitoring station as observations, the orbit determination calculation is performed again using the method from Step 2. The observation equations for orbit determination at this point are as follows:

[0183]

[0184]

[0185]

[0186] Step Six: Gross Error Detection. Using the solution results of unknown parameters such as orbit and clock error obtained in Step Five, calculate the theoretical observation value for each observation quantity, and then obtain the residual for each observation value. Data with residuals exceeding a certain limit are eliminated. Specifically, the condition for exceeding the limit is that the absolute value of the residual exceeds 5·σ. σ is statistically analyzed for inter-satellite pseudorange data, monitoring station pseudorange data, and monitoring station carrier phase data.

[0187] The formula for calculating theoretical observations is as follows:

[0188]

[0189]

[0190]

[0191] in, The theoretical observation values ​​of the inter-satellite pseudorange data obtained using the results of step five; The t is calculated using the orbital parameters obtained from the results of step five. i,j The position of satellite i at any given time; The t is calculated using the orbital parameters obtained from the results of step five. i,j -τ i,j The position of satellite j at any given time; and These are the clock error calculation values ​​for satellites i and j corresponding to clock error sampling point k, respectively. and These are the theoretical observation values ​​of the deionized carrier phase and pseudorange data of satellite i obtained from station r using the results of step five. This indicates the tropospheric delay obtained using the results of step five. This represents the clock difference of station r at the k-th sampling point obtained in step five; This represents the ambiguity parameter solution value obtained in step five. The formula omits correction terms for inter-satellite link transceiver delay, antenna phase center deviation, general relativistic delay, and phase entanglement effects of carrier phase data.

[0192] The residual calculation formulas for the three types of observations are as follows:

[0193]

[0194]

[0195]

[0196] Among them, V i,j (t i,j ), and Corresponding observations and The residual.

[0197] The corresponding statistical calculation formulas are as follows:

[0198]

[0199]

[0200]

[0201] W i,j (t i,j ), and They are respectively the corresponding V i,j (t i,j ), and The weights; N, N L and N P Corresponding observations and The number of.

[0202] Repeat steps three through six until the convergence condition is met.

[0203] Example 4

[0204] In order to implement the method corresponding to Embodiment 3 above and achieve the corresponding functions and technical effects, a BeiDou-3 satellite orbit determination and time synchronization system is provided below.

[0205] The system includes:

[0206] The orbit determination module is used to perform orbit determination and time synchronization calculations using observations within the orbit determination arc to obtain calculation parameters; the orbit determination arc is set with clock difference sampling points at certain intervals; the calculation parameters include: orbital parameters of each satellite and clock difference parameters of each satellite;

[0207] The posterior residual calculation module calculates the posterior residuals of the observed values ​​based on the solution parameters.

[0208] The clock speed calculation module is used to calculate the clock speed based on the posterior residual;

[0209] The correction module is used to correct the observed value according to the clock speed;

[0210] The recalculation module is used to recalculate orbit determination and time synchronization based on the corrected observations, and obtain the recalculated parameters.

[0211] The theoretical observation calculation module is used to calculate the theoretical observation value of the observation value based on the recalculated parameters.

[0212] The residual calculation and elimination module is used to calculate the residual based on the observed value and the theoretical observed value, and to eliminate observed values ​​whose residual exceeds a threshold.

[0213] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple; relevant parts can be referred to the method section.

[0214] This article uses specific examples to illustrate the principles and implementation methods of the invention. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. The described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

Claims

1. A method for orbit determination and time synchronization of BeiDou-3 satellites, characterized in that, include: Within the orbit determination arc, orbit determination and time synchronization are calculated using the observed values ​​to obtain the solution parameters; The orbital arc segment is equipped with clock difference sampling points at certain intervals; The calculation parameters include: orbital parameters of each satellite, clock difference parameters of each satellite, and clock speed parameters of each satellite; Calculate the theoretical observed value of the observed value based on the solution parameters; The residuals are calculated based on the observed values ​​and the theoretical observed values, and observed values ​​with residuals exceeding the threshold are removed. The process involves using observed values ​​to perform orbit determination and time synchronization calculations, resulting in solution parameters, specifically including: By performing orbit integration using the initial orbit information, a reference orbit, state transition matrix, and sensitivity matrix sampled at certain time intervals are obtained; The observation equations are linearized based on the reference orbit, the state transition matrix, and the sensitivity matrix; the observation equations are either observation equations based on inter-satellite pseudorange data / anchor station pseudorange data or joint observation equations based on inter-satellite pseudorange data and monitoring station data. The linearized observation equations are solved using the linear optimal estimation method to obtain the solution parameters; The observation equations for inter-satellite pseudorange data / anchor station pseudorange data are as follows: Among them, superscript and This indicates a satellite or anchorage, but not both simultaneously. Indicates satellite, Indicates anchorage station, for Time satellite or anchor station Satellite or anchoring station observed Pseudo-distance observations; Indicates the time it takes for the signal to propagate; This is the position vector of the satellite or anchorage station. Distance time Clock error parameters of the nearest clock error sampling point, either from a satellite or an anchor station; Indicates the clock speed parameter of the satellite or anchorage station; Indicates the observation time and the most recent clock difference sampling time. The time difference.

2. The method for orbit determination and time synchronization of BeiDou-3 satellites according to claim 1, characterized in that, The observed values ​​include inter-satellite pseudorange data and anchor station pseudorange data; the theoretical observed values ​​include theoretical observed values ​​of inter-satellite pseudorange data and theoretical observed values ​​of anchor station pseudorange data.

3. The method for orbit determination and time synchronization of BeiDou-3 satellites according to claim 1, characterized in that, The observed values ​​include inter-satellite pseudorange data and monitoring station data; the theoretical observed values ​​include theoretical observed values ​​of inter-satellite pseudorange data and theoretical observed values ​​of monitoring station data.

4. A BeiDou-3 satellite orbit determination and time synchronization system, characterized in that, include: The orbit determination calculation module is used to perform orbit determination and time synchronization calculations using observations within the orbit determination arc to obtain calculation parameters; The orbital arc segment is equipped with clock difference sampling points at certain intervals; The calculation parameters include: orbital parameters of each satellite, clock difference parameters of each satellite, and clock speed parameters of each satellite; The theoretical observation calculation module is used to calculate the theoretical observation value of the observation value based on the solution parameters; The residual calculation and elimination module is used to calculate the residual based on the observed value and the theoretical observed value, and to eliminate observed values ​​whose residual exceeds a threshold. The process involves using observed values ​​to perform orbit determination and time synchronization calculations, resulting in solution parameters, specifically including: By performing orbit integration using the initial orbit information, a reference orbit, state transition matrix, and sensitivity matrix sampled at certain time intervals are obtained; The observation equations are linearized based on the reference orbit, the state transition matrix, and the sensitivity matrix; the observation equations are either observation equations based on inter-satellite pseudorange data / anchor station pseudorange data or joint observation equations based on inter-satellite pseudorange data and monitoring station data. The linearized observation equations are solved using the linear optimal estimation method to obtain the solution parameters; The observation equations for inter-satellite pseudorange data / anchor station pseudorange data are as follows: Among them, superscript and This indicates a satellite or anchorage, but not both simultaneously. Indicates satellite, Indicates anchorage station, for Time satellite or anchor station Satellite or anchoring station observed Pseudo-distance observations; Indicates the time it takes for the signal to propagate; This is the position vector of the satellite or anchorage station. Distance time Clock error parameters of the nearest clock error sampling point, either from a satellite or an anchor station; Indicates the clock speed parameter of the satellite or anchorage station; Indicates the observation time and the most recent clock difference sampling time. The time difference.

5. A method for orbit determination and time synchronization of BeiDou-3 satellites, characterized in that, include: Within the orbit determination arc, orbit determination and time synchronization are calculated using the observed values ​​to obtain the solution parameters; The orbital arc segment is equipped with clock difference sampling points at certain intervals; The calculation parameters include: the orbital parameters of each satellite and the clock bias parameters of each satellite; Calculate the posterior residuals of the observed values ​​based on the solution parameters; The clock rate is calculated based on the posterior residuals; specifically, this includes: using the posterior residuals of the inter-satellite and anchor station pseudorange data obtained from the previous orbit determination calculation, the clock rates of the satellite and anchor stations are calculated, as follows: ;in, Indicates correspondence The posterior residuals; This indicates the pseudorange observations from inter-satellite or anchored stations used in the previous orbit determination; For the clock speed parameters of the satellite or anchorage station; Indicates the observation time up to the most recent clock difference sampling time Time difference; Indicates the time it takes for the signal to propagate; The observed value is corrected based on the clock speed; specifically, the formula is as follows: ;in, This represents the pseudorange data between satellites or anchored stations after clock speed correction; This indicates the pseudorange observations from inter-satellite or anchored stations used in the previous orbit determination; These are the clock velocity parameters of the satellite or the anchoring station, respectively, calculated based on the a posteriori residuals. Based on the corrected observations, orbit determination and time synchronization were recalculated to obtain the recalculated parameters. Calculate the theoretical observed value of the observed value based on the recalculated parameters; The residuals are calculated based on the observed values ​​and the theoretical observed values, and observed values ​​with residuals exceeding the threshold are removed. Within the orbit determination arc, orbit determination and time synchronization are calculated using observed values ​​to obtain solution parameters, specifically including: By performing orbit integration using the initial orbit information, a reference orbit, state transition matrix, and sensitivity matrix sampled at certain time intervals are obtained; The observation equations are linearized based on the reference orbit, the state transition matrix, and the sensitivity matrix; the observation equations are either observation equations based on inter-satellite pseudorange data / anchor station pseudorange data or joint observation equations based on inter-satellite pseudorange data and monitoring station data. The linearized observation equations are solved using the linear optimal estimation method to obtain the solution parameters; The observation equations for inter-satellite pseudorange data / anchor station pseudorange data are as follows: Among them, superscript and It can refer to a satellite or an anchoring station, but not both simultaneously. Indicates satellite, Indicates anchorage station, for Time satellite or anchor station Satellite or anchoring station observed Pseudo-distance observations; Indicates the time it takes for the signal to propagate; This is the position vector of the satellite or anchorage station. Distance time Recent clock difference sampling The clock bias parameters of the satellite or anchor station.

6. The method for orbit determination and time synchronization of BeiDou-3 satellites according to claim 5, characterized in that, The observations include inter-satellite pseudorange data and anchor station pseudorange data; the posterior residuals include the posterior residuals of the inter-satellite pseudorange data and the posterior residuals of the anchor station pseudorange data; the clock velocities include satellite clock velocities and anchor station clock velocities.

7. The method for orbit determination and time synchronization of BeiDou-3 satellites according to claim 5, characterized in that, The observations include inter-satellite pseudorange data and monitoring station data; the posterior residuals include the posterior residuals of the inter-satellite pseudorange data; and the clock speeds include satellite clock speeds.

8. A BeiDou-3 satellite orbit determination and time synchronization system, characterized in that, include: The orbit determination calculation module is used to perform orbit determination and time synchronization calculations using observations within the orbit determination arc to obtain calculation parameters; The orbital arc segment is equipped with clock difference sampling points at certain intervals; The calculation parameters include: the orbital parameters of each satellite and the clock bias parameters of each satellite; The posterior residual calculation module calculates the posterior residuals of the observed values ​​based on the solution parameters. The clock velocity calculation module is used to calculate the clock velocity based on the posterior residuals; specifically, it includes: using the posterior residuals of the inter-satellite and anchor station pseudorange data obtained from the previous orbit determination calculation, calculating the clock velocities of the satellite and anchor stations, as shown in the following formula: ;in, Indicates correspondence The posterior residuals; This indicates the pseudorange observations from inter-satellite or anchored stations used in the previous orbit determination; For the clock speed parameters of the satellite or anchorage station; Indicates the observation time up to the most recent clock difference sampling time Time difference; Indicates the time it takes for the signal to propagate; The correction module is used to correct the observed value according to the clock speed; specifically, the formula is as follows: ;in, This represents the pseudorange data between satellites or anchored stations after clock speed correction; This indicates the pseudorange observations from inter-satellite or anchored stations used in the previous orbit determination; These are the clock velocity parameters of the satellite or the anchoring station, respectively, calculated based on the a posteriori residuals. The recalculation module is used to recalculate orbit determination and time synchronization based on the corrected observations, and obtain the recalculated parameters. The theoretical observation calculation module is used to calculate the theoretical observation value of the observation value based on the recalculated parameters. The residual calculation and elimination module is used to calculate the residual based on the observed value and the theoretical observed value, and to eliminate observed values ​​whose residual exceeds a threshold. Within the orbit determination arc, orbit determination and time synchronization are calculated using observed values ​​to obtain solution parameters, specifically including: By performing orbit integration using the initial orbit information, a reference orbit, state transition matrix, and sensitivity matrix sampled at certain time intervals are obtained; The observation equations are linearized based on the reference orbit, the state transition matrix, and the sensitivity matrix; the observation equations are either observation equations based on inter-satellite pseudorange data / anchor station pseudorange data or joint observation equations based on inter-satellite pseudorange data and monitoring station data. The linearized observation equations are solved using the linear optimal estimation method to obtain the solution parameters; The observation equations for inter-satellite pseudorange data / anchor station pseudorange data are as follows: Among them, superscript and It can refer to a satellite or an anchoring station, but not both simultaneously. Indicates satellite, Indicates anchorage station, for Time satellite or anchor station Satellite or anchoring station observed Pseudo-distance observations; Indicates the time it takes for the signal to propagate; This is the position vector of the satellite or anchorage station. Distance time Recent clock difference sampling satellites or anchoring stations The clock difference parameter.

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