Navigation satellite real-time clock error estimation method and system and storage medium

Abstract

The invention provides a navigation satellite real-time clock error estimation method. The method comprises the following steps: obtaining accurate coordinates of each ground station by using a precise point positioning method; the satellite-borne GNSS observation data of each low-orbit satellite is used for dynamic precise orbit determination and forecasting, and orbit position coordinates of each low-orbit satellite in a certain arc section are obtained; dividing a regional ground station receiver and a low-orbit satellite-borne receiver into a plurality of subsets according to the models of the receivers, and respectively carrying out pseudo-range deviation calibration on the receivers in each subset; respectively constructing double-frequency ionosphere-free combined observed quantities of the regional ground station receiver and the low-orbit satellite-borne receiver on the navigation satellite, and carrying out pseudo-range deviation correction on the double-frequency ionosphere-free combined observed quantities; and performing navigation satellite real-time precision clock error estimation by using the double-frequency ionosphere-free combined observed quantity after the pseudo-range deviation correction to obtain a precision clock error parameter. According to the method, pseudo-range deviation correction is realized in navigation satellite real-time clock error estimation based on the space-ground combined observation data, and the navigation satellite real-time clock error estimation precision is improved.

Description

Technical Field

[0001] The present invention belongs to the field of satellite navigation technology, and relates to a navigation satellite real-time clock difference estimation method, system and storage medium, and in particular to a navigation satellite real-time clock difference estimation method that takes into account the pseudo-range bias correction of ground-based multi-source observation data. Background Art

[0002] Navigation satellite real-time clock error estimation technology was developed to meet the demand for real-time, precise positioning services. Its accuracy directly impacts the performance of these services. Because satellite atomic clocks are susceptible to various factors and difficult to accurately model and predict, high-precision, real-time navigation satellite clock errors must be estimated in real time through filtering. This is typically achieved using observational data from global or regional ground monitoring stations.

[0003] The technology for estimating the real-time clock difference of navigation satellites based on a global ground monitoring network is highly mature, and the accuracy of the estimated results meets the requirements for centimeter-level real-time GNSS positioning. However, when ground station distribution is limited and global ground monitoring station resources are insufficient, navigation satellite real-time clock difference estimation can only be performed using regional ground station networks. Compared to a global ground monitoring network, this approach faces the problem of clock error reconvergence caused by satellite entry and exit. This slow convergence of the clock error estimation results in a decrease in accuracy, ultimately impacting the performance of real-time precise positioning services.

[0004] Low-Earth Orbit (LEO) satellites carry GNSS receivers, which can serve as space-based stations for estimating real-time clock differences between navigation satellites. Because LEO satellites move rapidly and experience significant geometric changes, these satellites, along with regional ground stations, form a joint space-ground tracking observation system for navigation satellites. This can significantly improve the accuracy of real-time clock difference estimation for navigation satellites over regional ground-based monitoring networks alone.

[0005] Due to the non-ideal characteristics of downlink navigation signals from navigation satellites, receivers of different models (and different technical states) produce varying constant deviations in their response to the same satellite's downlink navigation signal, known as pseudorange bias. For a given navigation signal, the same receiver will have different pseudorange biases for different satellites, and receivers of different technical states will also have different pseudorange biases for the same satellite. When jointly estimating the real-time clock difference of navigation satellites using low-orbit space-based stations and regional ground stations, the diverse types of receivers involved in tracking observations inevitably lead to pseudorange biases between different receiver models. These biases are easily absorbed into the calculated navigation satellite clock difference during multi-source data processing, resulting in a decrease in clock accuracy. Summary of the Invention

[0006] The technical problem solved by the present invention is: to overcome the shortcomings of the existing technology, provide a navigation satellite real-time clock difference estimation method, system and storage medium, and eliminate the influence of pseudo-range deviation on the accuracy of navigation satellite real-time clock difference estimation in the case of joint ground-based data processing.

[0007] The technical solution of the present invention is:

[0008] The present invention discloses a method for estimating the real-time clock difference of a navigation satellite taking into account the correction of pseudo-range bias of multi-source observation data based on the ground and space, comprising:

[0009] Using ground station receivers, dual-frequency pseudorange observations and carrier phase observations are obtained. Combined with the precise orbit and clock products of navigation satellites, static precise point positioning is used to obtain the position coordinates of each ground station receiver and the static precise point positioning pseudorange residuals.

[0010] Using the onboard receiver of the low-orbit satellite, dual-frequency pseudorange observations and carrier phase observations are obtained; combined with the precise orbit and clock products of the navigation satellite, the orbital position coordinates of the low-orbit satellite and the pseudorange residuals of the low-orbit satellite dynamic precise orbit determination are obtained through dynamic precise orbit determination and prediction;

[0011] Based on the static precise point positioning pseudorange residuals and the low-orbit satellite dynamic precise orbit determination pseudorange residuals, the pseudorange deviations of the ground station receiver and the low-orbit satellite-borne receiver to each navigation satellite are calculated respectively;

[0012] The dual-frequency ionospheric-free pseudorange observation values of the ground station receiver and the low-orbit satellite onboard receiver are respectively used to correct the pseudorange bias values of each navigation satellite using the ground station receiver and the low-orbit satellite onboard receiver to obtain the corrected ground-to-ground observation data;

[0013] Based on the corrected ground-based observation data, the navigation satellite orbit, ground station coordinates and low-orbit satellite orbit are fixed, and the navigation satellite clock error is estimated in real time.

[0014] Furthermore, in the above method, the position coordinates and static precise point positioning pseudorange residuals of each ground station receiver are obtained as follows:

[0015] Construct dual-frequency ionospheric-free combined observations of navigation satellites by ground station receivers;

[0016] Correction of orbit error, clock error, tropospheric delay, solid tide, Windup effect, Sagnac effect, satellite hardware delay bias, satellite antenna phase center bias, and gravitational delay effect in dual-frequency ionosphere-free combined observations;

[0017] Through the static precise point positioning method, based on the corrected dual-frequency ionospheric-free combined observations, the position coordinates of each ground station receiver are solved, and the pseudorange residual sequence is stored to obtain the static precise point positioning pseudorange residual.

[0018] Furthermore, in the above method, obtaining the low-orbit satellite orbital position coordinates and the low-orbit satellite dynamic precise orbit determination pseudorange residuals is specifically as follows:

[0019] Construct dual-frequency ionospheric-free combined observations of navigation satellites by low-orbit satellite-borne receivers;

[0020] Based on the dual-frequency ionospheric-free combined observations, the navigation satellite orbit and clock error are fixed, and a dynamic model is used to perform precise orbit determination of the low-orbit satellite to obtain orbit determination parameters;

[0021] Based on the orbit determination parameters, the orbit coordinates of the low-orbit satellite are predicted, and the pseudo-range residual sequence is stored to obtain the pseudo-range residuals of the low-orbit satellite dynamic precise orbit determination.

[0022] Furthermore, in the above method, the calculation of the pseudorange deviation value of the ground station receiver and the low-orbit satellite-borne receiver to each navigation satellite is specifically as follows:

[0023] According to the receiver model, ground station receivers and low-orbit satellite onboard receivers are divided into several subsets;

[0024] For each subset, the mean of the multi-epoch pseudorange residuals of the receiver to each navigation satellite is calculated as the pseudorange bias of a single receiver;

[0025] The pseudorange deviations of all receivers in the same subset are averaged to obtain the pseudorange deviation value of this model of receiver for each navigation satellite.

[0026] Furthermore, in the above method, the pseudorange deviation correction is specifically:

[0027] The dual-frequency ionospheric-free pseudorange observation values of the ground station receiver and the low-orbit satellite onboard receiver are respectively subtracted from the pseudorange bias values of the corresponding receiver models to the navigation satellite to obtain the corrected ground-to-ground observation data.

[0028] Furthermore, in the above method, the navigation satellite clock error is estimated in real time based on the corrected ground-based observation data, fixing the navigation satellite orbit, ground station coordinates and low-orbit satellite orbit, specifically:

[0029] Based on the corrected ground-based observation data, combined with the navigation satellite orbit coordinates, ground station coordinates and low-orbit satellite orbit coordinates, Kalman filtering is used to estimate the navigation satellite clock error.

[0030] The present invention discloses a navigation satellite real-time clock difference estimation system, comprising:

[0031] The ground data acquisition and positioning module obtains pseudorange and carrier phase observation data of the F1 and F2 frequency points from m ground station receivers, combines the navigation satellite orbit and clock products released by the IGS, calculates the coordinates of the ground station receiver through static precise single point positioning, and outputs the pseudorange residual sequence;

[0032] The space-based data acquisition and orbit determination module obtains pseudorange and carrier phase observation data at the F1 and F2 frequency points from the onboard receivers of n low-orbit satellites. Combined with the navigation satellite orbit and clock error products released by the IGS, it generates the low-orbit satellite orbit position coordinates through dynamic precise orbit determination and prediction, and outputs a pseudorange residual sequence;

[0033] a pseudorange deviation calibration module that classifies ground station receivers and low-orbit satellite-borne receivers according to receiver models; calculates the pseudorange deviation value of the ground station receiver for each navigation satellite based on the pseudorange residuals output by the ground-based data acquisition and positioning module; and calculates the pseudorange deviation value of the low-orbit satellite-borne receiver for each navigation satellite based on the pseudorange residuals output by the space-based data acquisition and orbit determination module;

[0034] An observation value correction module corrects the dual-frequency ionospheric-free pseudorange observation values of the ground station receiver and the low-orbit satellite onboard receiver using the deviation values calculated by the pseudorange deviation calibration module;

[0035] The clock error calculation module fixes the navigation satellite orbit, ground station coordinates and low-orbit satellite orbit position; based on the corrected ground-based observation data, it uses Kalman filtering to calculate the navigation satellite precise clock error, receiver clock error, tropospheric delay and ambiguity parameters in real time.

[0036] The present invention discloses a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, a navigation satellite real-time clock difference estimation method taking into account the pseudo-range deviation correction of ground-based multi-source observation data is realized.

[0037] The beneficial effects of the present invention and the prior art are:

[0038] (1) The present invention relies on the pseudorange residual characteristics in positioning and orbit determination to realize the calculation of pseudorange deviations for different receiver types, solving the problem that pseudorange deviations are difficult to accurately calibrate;

[0039] (2) The present invention addresses the pseudorange bias problem that has been ignored in the prior art. It adopts a ground-to-space multi-source measurement model that takes pseudorange bias into account, eliminates the adverse effects of pseudorange bias in the case of ground-to-space joint data processing, and improves the accuracy of real-time clock difference estimation of navigation satellites. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 Flow chart of the method of the present invention. DETAILED DESCRIPTION

[0041] The present invention will be further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0042] The present invention discloses a method for estimating the real-time clock difference of a navigation satellite taking into account the correction of pseudo-range bias of multi-source observation data based on the ground and space, comprising:

[0043] Using ground station receivers, dual-frequency pseudorange observations and carrier phase observations are obtained. Combined with the precise orbit and clock products of navigation satellites, static precise point positioning is used to obtain the position coordinates of each ground station receiver and the static precise point positioning pseudorange residuals.

[0044] Using the onboard receiver of the low-orbit satellite, dual-frequency pseudorange observations and carrier phase observations are obtained; combined with the precise orbit and clock products of the navigation satellite, the orbital position coordinates of the low-orbit satellite and the pseudorange residuals of the low-orbit satellite dynamic precise orbit determination are obtained through dynamic precise orbit determination and prediction;

[0045] Based on the static precise point positioning pseudorange residuals and the low-orbit satellite dynamic precise orbit determination pseudorange residuals, the pseudorange deviations of the ground station receiver and the low-orbit satellite-borne receiver to each navigation satellite are calculated respectively;

[0046] The dual-frequency ionospheric-free pseudorange observation values of the ground station receiver and the low-orbit satellite onboard receiver are respectively used to correct the pseudorange bias values of each navigation satellite using the ground station receiver and the low-orbit satellite onboard receiver to obtain the corrected ground-to-ground observation data;

[0047] Based on the corrected ground-based observation data, the navigation satellite orbit, ground station coordinates and low-orbit satellite orbit are fixed, and the navigation satellite clock error is estimated in real time.

[0048] Preferably, the obtaining of the position coordinates and static precise point positioning pseudorange residuals of each ground station receiver is specifically as follows:

[0049] Construct dual-frequency ionospheric-free combined observations of navigation satellites by ground station receivers;

[0050] Correction of orbit error, clock error, tropospheric delay, solid tide, Windup effect, Sagnac effect, satellite hardware delay bias, satellite antenna phase center bias, and gravitational delay effect in dual-frequency ionosphere-free combined observations;

[0051] Through the static precise point positioning method, based on the corrected dual-frequency ionospheric-free combined observations, the position coordinates of each ground station receiver are solved, and the pseudorange residual sequence is stored to obtain the static precise point positioning pseudorange residual.

[0052] Preferably, the obtaining of the low-orbit satellite orbital position coordinates and the low-orbit satellite dynamics precise orbit determination pseudorange residuals is specifically as follows:

[0053] Construct dual-frequency ionospheric-free combined observations of navigation satellites by low-orbit satellite-borne receivers;

[0054] Based on the dual-frequency ionospheric-free combined observations, the navigation satellite orbit and clock error are fixed, and a dynamic model is used to perform precise orbit determination of the low-orbit satellite to obtain orbit determination parameters;

[0055] Based on the orbit determination parameters, the orbit coordinates of the low-orbit satellite are predicted, and the pseudo-range residual sequence is stored to obtain the pseudo-range residuals of the low-orbit satellite dynamic precise orbit determination.

[0056] Preferably, the calculation of the pseudorange deviation value of the ground station receiver and the low-orbit satellite-borne receiver to each navigation satellite is specifically as follows:

[0057] According to the receiver model, ground station receivers and low-orbit satellite onboard receivers are divided into several subsets;

[0058] For each subset, the mean of the multi-epoch pseudorange residuals of the receiver to each navigation satellite is calculated as the pseudorange bias of a single receiver;

[0059] The pseudorange deviations of all receivers in the same subset are averaged to obtain the pseudorange deviation value of this model of receiver for each navigation satellite.

[0060] Preferably, the pseudorange deviation correction is specifically:

[0061] The dual-frequency ionospheric-free pseudorange observation values of the ground station receiver and the low-orbit satellite onboard receiver are respectively subtracted from the pseudorange bias values of the corresponding receiver models to the navigation satellite to obtain the corrected ground-to-ground observation data.

[0062] Preferably, the method of fixing the navigation satellite orbit, ground station coordinates and low-orbit satellite orbit based on the corrected ground-based observation data and estimating the navigation satellite clock error in real time is specifically as follows:

[0063] Based on the corrected ground-based observation data, combined with the navigation satellite orbit coordinates, ground station coordinates and low-orbit satellite orbit coordinates, Kalman filtering is used to estimate the navigation satellite clock error.

[0064] The present invention discloses a navigation satellite real-time clock difference estimation system, comprising:

[0065] The ground data acquisition and positioning module obtains pseudorange and carrier phase observation data of the F1 and F2 frequency points from m ground station receivers, combines the navigation satellite orbit and clock products released by the IGS, calculates the coordinates of the ground station receiver through static precise single point positioning, and outputs the pseudorange residual sequence;

[0066] The space-based data acquisition and orbit determination module obtains pseudorange and carrier phase observation data at the F1 and F2 frequency points from the onboard receivers of n low-orbit satellites. Combined with the navigation satellite orbit and clock error products released by the IGS, it generates the low-orbit satellite orbit position coordinates through dynamic precise orbit determination and prediction, and outputs a pseudorange residual sequence;

[0067] a pseudorange deviation calibration module that classifies ground station receivers and low-orbit satellite-borne receivers according to receiver models; calculates the pseudorange deviation value of the ground station receiver for each navigation satellite based on the pseudorange residuals output by the ground-based data acquisition and positioning module; and calculates the pseudorange deviation value of the low-orbit satellite-borne receiver for each navigation satellite based on the pseudorange residuals output by the space-based data acquisition and orbit determination module;

[0068] An observation value correction module corrects the dual-frequency ionospheric-free pseudorange observation values of the ground station receiver and the low-orbit satellite onboard receiver using the deviation values calculated by the pseudorange deviation calibration module;

[0069] The clock error calculation module fixes the navigation satellite orbit, ground station coordinates and low-orbit satellite orbit position; based on the corrected ground-based observation data, it uses Kalman filtering to calculate the navigation satellite precise clock error, receiver clock error, tropospheric delay and ambiguity parameters in real time.

[0070] The present invention discloses a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, a navigation satellite real-time clock difference estimation method taking into account the pseudo-range deviation correction of ground-based multi-source observation data is implemented.

[0071] Example

[0072] like Figure 1 As shown, the present invention provides a navigation satellite real-time clock error estimation method that takes into account the pseudo-range bias correction of ground-based multi-source observation data, including the following steps:

[0073] 1) Using m ground station receivers to form a regional monitoring station network, the precise position coordinates of each ground station receiver are calculated using the pseudorange observation values and carrier phase observation values of the two frequency points F1 and F2 of each ground station receiver, and the precise orbit and clock products of the navigation satellite provided by the IGS Analysis Center.

[0074] 2) Using n low-orbit satellites equipped with onboard receivers to form a space-based monitoring network, the pseudo-range observations and carrier phase observations of the two frequency points F1 and F2 of each onboard receiver are used, and the precise orbit and clock products of navigation satellites released by the IGS Analysis Center are selected. The orbital position coordinates of the low-orbit satellites in a specific arc segment are obtained through dynamic precise orbit determination and prediction;

[0075] 3) Based on the PPP pseudorange residual, calculate the pseudorange deviation value of the regional ground station receiver to each navigation satellite;

[0076] 4) Based on the pseudo-range residuals of the LEO satellite dynamics precise orbit determination, calculate the pseudo-range deviation value of the LEO satellite-borne receiver to each navigation satellite;

[0077] 5) Construct dual-frequency ionospheric-free combined observations of navigation satellites by regional ground station receivers and low-orbit satellite-borne receivers, and perform pseudorange bias correction on the observations;

[0078] 6) Combined use of dual-frequency ionospheric-free combined observations after pseudo-range bias correction by regional ground station receivers and low-orbit satellite onboard receivers to fix the navigation satellite orbits, the position coordinates of each ground station receiver, and the position coordinates of each low-orbit satellite onboard receiver, and estimate the precise clock error of the navigation satellite in real time;

[0079] The step 1) obtains the precise position coordinates of each ground station receiver through precise point positioning. Taking ground station receiver i and Beidou navigation satellite as an example, the specific steps are:

[0080] 11) Use the ground station receiver i to construct the dual-frequency ionospheric-free combined observations of the pseudorange observations and carrier phase observations of each BeiDou navigation satellite at the two frequency points F1 and F2, as follows:

[0081]

[0082] P IF and L IF are the pseudorange and carrier phase observation values after dual-frequency ionosphere-free combination, f1 and f2 are the frequencies of F1 and F2 respectively, P1 and P2 are the pseudorange observation values of F1 and F2 respectively, and L1 and L2 are the carrier phase observation values of F1 and F2 respectively;

[0083] 12) Use the precise orbit and clock products of navigation satellites released by the IGS Analysis Center to calculate the orbit and clock errors of Beidou navigation satellites;

[0084] 13) Using the Saastamoinen model, the tropospheric delay error of the dual-frequency ionosphere-free combined observations is corrected, and the estimated parameters are added to absorb the residual error of the model;

[0085] 14) Perform various error corrections on the dual-frequency ionosphere-free combined observations, mainly including solid tide, Windup effect, Sagnac effect, satellite hardware delay bias, satellite antenna phase center bias, gravity delay effect, etc.

[0086] 15) Use the error-corrected dual-frequency ionosphere-free pseudorange and carrier observations to perform precise point positioning to obtain the precise position coordinates of the ground station receiver, and store the pseudorange residual sequence generated by the precise point positioning solution for subsequent use;

[0087] The step 2) obtains the low-orbit satellite orbital position coordinates of a specific arc segment by dynamic precise orbit determination and prediction, taking the low-orbit satellite onboard receiver j and Beidou navigation satellite as an example, specifically:

[0088] 21) Obtain pseudorange observation values and carrier phase observation values of the Beidou navigation satellite at the two frequency points F1 and F2 of the low-orbit satellite onboard receiver j within a certain arc segment, and construct dual-frequency ionospheric-free combined observation values of pseudorange and carrier phase respectively, as in step 11);

[0089] 22) Download the BeiDou navigation satellite precise orbit and clock products for the same time period as the onboard observation data in step 21) from the IGS analysis center, and interpolate the BeiDou navigation satellite position and clock error at the corresponding time;

[0090] 23) Using the dual-frequency ionospheric-free combined observations of pseudorange and carrier phase obtained in step 21) as orbit determination observation input, and fixing the BeiDou navigation satellite position and clock error calculated in step 22), dynamic precise orbit determination and prediction are performed. The observation equation is as follows:

[0091] L=Gx0+ε

[0092] Where L is the observation value of the BeiDou navigation satellite by the LEO satellite onboard receiver j, G is the observation coefficient matrix of the LEO satellite onboard receiver, x0 is the parameters to be estimated for precise orbit determination, including the LEO satellite initial orbit parameters, onboard receiver clock error parameters, ambiguity parameters and dynamic model parameters, and ε is the observation error.

[0093] At the same time, the pseudorange residual sequence generated by dynamic precise orbit determination is stored for subsequent use;

[0094] 24) Using the initial orbit parameters and dynamic model parameters of the low-orbit satellite obtained in step 23), the low-orbit satellite orbit can be integrally predicted to obtain the orbital position coordinates of the low-orbit satellite in the predicted arc;

[0095] The step 3) calculates the pseudorange deviation value of the regional ground station receiver to each navigation satellite based on the PPP pseudorange residual, specifically:

[0096] 31) Divide the regional ground station receivers into several subsets according to the receiver model, and the receiver models in the same subset are the same;

[0097] 32) For each receiver in the subset, from the pseudorange residual sequence obtained in step 15) from the ground station receiver PPP solution, calculate the average value of the multi-epoch pseudorange residual of each navigation satellite as the pseudorange bias of the receiver to the navigation satellite, and traverse the calculation for all receivers in the subset in turn;

[0098] 33) Calculating an average of the pseudorange deviations of all receivers in the subset obtained in step 32) for each navigation satellite, and using the average as the pseudorange deviation value of the receiver model for each navigation satellite;

[0099] 34) Traversing all subsets according to steps 31) to 33) to obtain pseudorange deviation values of ground station receivers of different models in different regions for each navigation satellite;

[0100] The step 4) calculates the pseudorange deviation value of the low-orbit satellite-borne receiver to each navigation satellite based on the pseudorange residual of the low-orbit satellite dynamics precise orbit determination, specifically:

[0101] 41) Divide the low-orbit satellite onboard receivers into several subsets according to the receiver model, and the receiver models in the same subset are the same;

[0102] 42) For each receiver in the subset, from the pseudorange residual sequence of the dynamic precise orbit determination of the low-orbit satellite-borne receiver obtained in step 23), calculate the average of the multi-epoch pseudorange residuals of each navigation satellite as the pseudorange bias of the receiver to the navigation satellite, and traverse the calculation for all receivers in the subset in turn;

[0103] 43) Calculating an average of the pseudorange deviations of all receivers in the subset obtained in step 42) for each navigation satellite, and using the average as the pseudorange deviation value of the receiver model for each navigation satellite;

[0104] 44) Traversing all subsets according to steps 41) to 43) to obtain pseudorange deviation values of different types of low-orbit satellite onboard receivers for each navigation satellite;

[0105] Said step 5) constructs a regional ground station receiver and a low-orbit satellite onboard receiver to respectively measure the navigation satellite pseudorange and carrier phase dual-frequency ionospheric-free combined observations, and performs pseudorange bias correction on the pseudorange observations, specifically:

[0106] 51) Take the regional ground station receiver i for BeiDou navigation satellite k as an example, the details are as follows:

[0107]

[0108] in: is the dual-frequency ionospheric-free pseudorange observation value of the regional ground station receiver i to the BeiDou navigation satellite k, The pseudorange deviation value of the ground station receiver of this model area to the Beidou navigation satellite k obtained in step 34) is is the observed value after pseudorange bias correction;

[0109] 52) Take the low-orbit satellite onboard receiver j for BeiDou navigation satellite k as an example, the details are as follows:

[0110]

[0111] in: is the dual-frequency ionospheric-free pseudorange observation value of BeiDou navigation satellite k by low-orbit satellite onboard receiver j, The pseudorange deviation value of the low-orbit satellite onboard receiver of this model to the Beidou navigation satellite k obtained in step 44) is: is the observed value after pseudorange bias correction;

[0112] The step 6) estimates the precise clock error of the navigation satellite in real time, specifically:

[0113] 61) Using the dual-frequency ionospheric-free combined pseudorange and carrier phase observations of the regional ground station receiver and the low-orbit satellite onboard receiver as observations for real-time estimation of the navigation satellite precise clock error, wherein the dual-frequency ionospheric-free combined pseudorange observations of the regional ground station receiver are the observations corrected for the pseudorange bias obtained in step 51), and the dual-frequency ionospheric-free combined pseudorange observations of the low-orbit satellite onboard receiver are the observations corrected for the pseudorange bias obtained in step 52);

[0114] 62) During the data processing of the real-time precise clock error estimation of the navigation satellite, the precise orbit products of the navigation satellites released by the IGS Analysis Center are used to calculate the orbital position coordinates of the navigation satellites. The coordinates of the ground station receivers in each region are fixed to the precise position coordinates of the ground station receivers obtained in step 15), and the coordinates of the onboard receivers of each low-orbit satellite are fixed to the orbital position coordinates of the low-orbit satellites in the predicted arc segment obtained in step 24);

[0115] 63) The Kalman filter method is used to estimate the receiver clock errors of ground stations in each region, the receiver clock errors of low-orbit satellites, the tropospheric delay in the zenith direction of ground station receivers in each region, the carrier phase ambiguity parameters and the precise clock errors of navigation satellites in real time and epoch by epoch, so as to achieve rapid convergence of the precise clock error estimation results of navigation satellites.

[0116] Although the present invention has been described in detail through the above preferred embodiments, it should be understood that the above description is not intended to limit the present invention. After reading the above description, various modifications and substitutions of the present invention will become apparent to those skilled in the art. Therefore, the scope of protection of the present invention should be defined by the appended claims.

[0117] The contents not described in detail in the specification of the present invention belong to the common knowledge of professionals in this field.

Claims

1. A method for estimating real-time clock errors of navigation satellites taking into account pseudorange bias correction of multi-source observation data from ground-based observations, characterized in that: include: Using ground station receivers, dual-frequency pseudorange observations and carrier phase observations are obtained. Combined with the precise orbit and clock products of navigation satellites, static precise point positioning is used to obtain the position coordinates of each ground station receiver and the static precise point positioning pseudorange residuals. Using the onboard receiver of the low-orbit satellite, dual-frequency pseudorange observations and carrier phase observations are obtained; combined with the precise orbit and clock products of the navigation satellite, the orbital position coordinates of the low-orbit satellite and the pseudorange residuals of the low-orbit satellite dynamic precise orbit determination are obtained through dynamic precise orbit determination and prediction; Based on the static precise point positioning pseudorange residuals and the low-orbit satellite dynamic precise orbit determination pseudorange residuals, the pseudorange deviations of the ground station receiver and the low-orbit satellite-borne receiver for each navigation satellite are calculated respectively; The dual-frequency ionospheric-free pseudorange observation values of the ground station receiver and the low-orbit satellite onboard receiver are respectively used to correct the pseudorange bias values of each navigation satellite using the ground station receiver and the low-orbit satellite onboard receiver to obtain the corrected ground-to-ground observation data; Based on the corrected ground-based observation data, the navigation satellite orbit, ground station coordinates and low-orbit satellite orbit are fixed, and the navigation satellite clock error is estimated in real time.

2. The method according to claim 1, characterized in that The position coordinates and static precise point positioning pseudorange residuals of each ground station receiver are obtained as follows: Construct dual-frequency ionospheric-free combined observations of navigation satellites by ground station receivers; Correction of orbit error, clock error, tropospheric delay, solid tide, Windup effect, Sagnac effect, satellite hardware delay bias, satellite antenna phase center bias, and gravitational delay effect in dual-frequency ionosphere-free combined observations; Through the static precise point positioning method, based on the corrected dual-frequency ionospheric-free combined observations, the position coordinates of each ground station receiver are solved, and the pseudorange residual sequence is stored to obtain the static precise point positioning pseudorange residual.

3. The method according to claim 1, characterized in that The obtaining of the low-orbit satellite orbital position coordinates and the low-orbit satellite dynamics precise orbit determination pseudorange residuals is specifically as follows: Construct dual-frequency ionospheric-free combined observations of navigation satellites by low-orbit satellite-borne receivers; Based on the dual-frequency ionospheric-free combined observations, the navigation satellite orbit and clock error are fixed, and a dynamic model is used to perform precise orbit determination of the low-orbit satellite to obtain orbit determination parameters; Based on the orbit determination parameters, the orbit coordinates of the low-orbit satellite are predicted, and the pseudo-range residual sequence is stored to obtain the pseudo-range residuals of the low-orbit satellite dynamic precise orbit determination.

4. The method according to claim 1, wherein The calculation of the pseudorange deviation values of the ground station receiver and the low-orbit satellite-borne receiver for each navigation satellite is specifically as follows: According to the receiver model, ground station receivers and low-orbit satellite onboard receivers are divided into several subsets; For each subset, the mean of the multi-epoch pseudorange residuals of the receiver to each navigation satellite is calculated as the pseudorange bias of a single receiver; The pseudorange deviations of all receivers in the same subset are averaged to obtain the pseudorange deviation value of this model of receiver for each navigation satellite.

5. The method according to claim 1, characterized in that The pseudorange deviation correction is specifically as follows: The dual-frequency ionospheric-free pseudorange observation values of the ground station receiver and the low-orbit satellite onboard receiver are respectively subtracted from the pseudorange bias values of the corresponding receiver models to the navigation satellite to obtain the corrected ground-to-ground observation data.

6. The method according to claim 1, characterized in that The method of estimating the navigation satellite clock error in real time based on the corrected ground-based observation data, fixing the navigation satellite orbit, ground station coordinates and low-orbit satellite orbit is specifically as follows: Based on the corrected ground-based observation data, combined with the navigation satellite orbit coordinates, ground station coordinates and low-orbit satellite orbit coordinates, Kalman filtering is used to estimate the navigation satellite clock error.

7. A navigation satellite real-time clock difference estimation system, characterized in that: include: The ground data acquisition and positioning module obtains pseudorange and carrier phase observation data of the F1 and F2 frequency points from m ground station receivers, combines the navigation satellite orbit and clock products released by the IGS, calculates the coordinates of the ground station receiver through static precise single point positioning, and outputs the pseudorange residual sequence; The space-based data acquisition and orbit determination module obtains pseudorange and carrier phase observation data at the F1 and F2 frequency points from the onboard receivers of n low-orbit satellites. Combined with the navigation satellite orbit and clock error products released by the IGS, it generates the low-orbit satellite orbit position coordinates through dynamic precise orbit determination and prediction, and outputs a pseudorange residual sequence; The pseudorange deviation calibration module classifies ground station receivers and low-orbit satellite-borne receivers according to receiver models; calculates the pseudorange deviation value of the ground station receiver for each navigation satellite based on the pseudorange residual output by the ground data acquisition and positioning module; Calculating the pseudorange deviation value of each navigation satellite from the low-orbit satellite-borne receiver based on the pseudorange residual output by the space-based data acquisition and orbit determination module; An observation value correction module corrects the dual-frequency ionospheric-free pseudorange observation values of the ground station receiver and the low-orbit satellite onboard receiver using the deviation values calculated by the pseudorange deviation calibration module; The clock error calculation module fixes the navigation satellite orbit, ground station coordinates and low-orbit satellite orbit position; based on the corrected ground-based observation data, it uses Kalman filtering to calculate the navigation satellite precise clock error, receiver clock error, tropospheric delay and ambiguity parameters in real time.

8. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, a navigation satellite real-time clock difference estimation method taking into account pseudo-range bias correction of ground-based multi-source observation data according to any one of claims 1 to 6 is implemented.

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