Observation value weighting method for navigation satellite precision data processing

Abstract

The invention relates to the technical field of high-precision positioning and orbit determination of a global navigation satellite system (GNSS), in particular to an observation value weighting method for navigation satellite precision data processing, which comprises the following steps of: 1, constructing a GNSS precision data processing observation model; 2, determining the weight of the pseudo-range observed quantity; step 3, phase observed quantity weighting; and 4, based on the epoch weights of the satellites determined in the step 3, repeating the steps 1-3, and calculating a final precision positioning orbit determination result through iterative calculation. According to the method, satellite observation information can be fully utilized through satellite-by-satellite epoch-by-epoch observation quantity weighting, the situation that the satellite observation quantity of the whole arc section is deleted due to the fact that the observation quality of a satellite in part of time periods is poor is avoided, satellite-by-satellite epoch-by-epoch observation quantity fine weighting is creatively achieved on the basis of observation value post-test residual errors, and GNSS precise positioning and orbit determination performance is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of high-precision positioning and orbit determination of the Global Navigation Satellite System (GNSS), and specifically to an observation value weighting method for precise data processing of navigation satellites. Background Art

[0002] Global Navigation Satellite Systems represented by GPS of the United States, BDS (Beidou) of China, GLONASS of Russia, and Galileo of Europe can provide centimeter-level or higher positioning accuracy in the fields of earth science, surveying and mapping, agriculture, unmanned driving, aerospace, logistics, and disaster monitoring, significantly facilitating the life of human society. To achieve high-precision applications of GNSS, it is necessary to use global or regional tracking station equipment to receive navigation satellite signals from tens of thousands of kilometers above the ground, obtain pseudo-range and phase observation information between the satellite and the ground, and obtain high-precision satellite orbits or tracking station coordinates through precise processing of pseudo-range and phase data.

[0003] However, the downlink signals of navigation satellites are emitted from satellite antennas and need to propagate through the atmosphere to the tracking station receiving equipment. Affected by atmospheric delay, observation environment errors, observation noise, etc., and there are differences in the propagation paths of downlink signals of different satellites. Therefore, there are spatio-temporal differences in the quality of pseudo-range and phase observation values of different satellites in different systems. In GNSS precise data processing, it is necessary to give appropriate weights to pseudo-range and phase observation values to obtain high-precision positioning and orbit determination processing results. Traditional observation value weighting methods generally use empirical methods such as elevation angle and signal-to-noise ratio to achieve the weight configuration of observations, and there are mainly the following problems: The applicability of empirical observation value weighting methods is poor, especially in tracking stations with complex observation environments. The observations are greatly affected by multipath. Only using the elevation angle for weighting cannot obtain appropriate weights. At the same time, not all the observation data files of the International GNSS Service (IGS) global tracking stations provide signal-to-noise ratio information. Therefore, these stations cannot use the signal-to-noise ratio empirical weighting method to set the weights of observations. In addition, for the precise data processing of long arc segments after the event, abnormal satellites are often removed through satellite observation residuals, which easily results in low utilization rate of observation data. Finally, for multi-system precise data processing, the weighting method based on elevation angle has not considered the differences in receiver observation noise caused by the signal quality between different systems.

[0004] In view of the above problems, the present invention starts from the a posteriori residuals of observations and establishes an observation value weighting method and system for GNSS precise data processing. Summary of the Invention

[0005] The purpose of the present invention is to provide an observation value weighting method for precise data processing of navigation satellites to solve the problems raised in the above background art.

[0006] To achieve the above object, the present invention provides the following technical solutions: An observation value weighting method for precise data processing of navigation satellites, comprising the following steps: Step 1, construct a GNSS precise data processing observation model: use the GNSS signal tracking equipment of global tracking stations to collect GNSS observation data, eliminate gross error data, mark phase cycle slips, establish a pseudorange observation equation and a phase observation equation, and use the least squares principle to solve for the estimated values of the parameters to be estimated; Step 2, weight the pseudorange observation: substitute the estimated values of the parameters to be estimated back into the pseudorange observation equation to calculate the pseudorange residuals, and calculate the weights of the pseudorange observations level by level, epoch by epoch, and satellite by satellite; Step 3, weight the phase observation: substitute the estimated values of the parameters to be estimated back into the phase observation equation to calculate the phase residuals, perform phase small cycle slip detection based on the phase residual sequence, calculate the mean value of the residuals by segmenting the phase residuals according to the cycle slips and subtract it from the phase residuals to obtain the updated phase residuals, and calculate the weights of the phase observations level by level, epoch by epoch, and satellite by satellite; Step 4, based on the weights of each satellite and each epoch determined in Step 3, repeat Steps 1-3, and calculate the final precise positioning and orbit determination results through iterative calculation.

[0007] Preferably, the pseudorange observation equation and the phase observation equation in Step 1 are as follows: (1); In Equation (1): and : respectively represent the pseudorange and phase measurement values; : the geometric distance between the station and the satellite; s : satellite number; r : receiver number; i : frequency point number; c : the speed of light in vacuum; : receiver clock error; : satellite clock error; : ionospheric delay projection function; : zenith ionospheric delay at the station; : tropospheric mapping function; : zenith tropospheric delay; : carrier phase integer ambiguity parameter; : the i wavelength of the th , : The pseudorange observation value receiver and phase - end hardware delay of the i th frequency point; , : The phase observation value receiver and satellite - end hardware delay of the i th frequency point; , : Respectively the pseudorange and phase multipath effects and noise of the i th frequency point.

[0008] Preferably, the calculation method of the pseudorange residual in step 2 is: (2); In formula (2): : Pseudorange residual.

[0009] Preferably, the specific process of calculating the pseudorange observation value weight level - by - level, epoch - by - epoch, and satellite - by - satellite in step 2 includes: The calculation method of the pseudorange observation value weight is: (3); In formula (3): j: Iteration number; : The pseudorange observation value weight of satellite s at frequency point i determined by the j - th iteration calculation, with the initial weight being 1; , : Empirical coefficient, set according to the iteration number; : Standard deviation calculated based on the residuals of all satellite pseudorange observation values.

[0010] Preferably, the standard deviation calculated based on the residuals of all satellite pseudorange observation values (4); In formula (4): : Weighted mean of the pseudorange observation value residuals of satellite s at frequency point i; : The pseudorange observation value weight of satellite s at frequency point i determined by the (j - 1) - th iteration calculation.

[0011] Preferably, the calculation method of the weighted mean of the pseudorange observation value residuals of satellite s at frequency point i (5).

[0012] Preferably, the calculation method of the phase residual in step 3 is as follows: (6); In formula (6): : Phase residual.

[0013] Preferably, the method of detecting small cycle slips of the phase based on the phase residual sequence in step 3, calculating the mean value of the residuals by segmenting the phase residuals according to the cycle slips, and subtracting it from the phase residuals to obtain the updated phase residuals specifically includes: (7); In formula (7): and respectively represent the updated phase residual and the mean value of the residual segments.

[0014] Preferably, the specific method of calculating the weights of the phase observations by hierarchical epoch-by-epoch and satellite-by-satellite in step 2 includes: The calculation method of the weights of the phase observations is (8); In formula (8): : The weight of the phase observation of satellite s at frequency point i determined by the j-th iterative calculation, and the initial weight is 1; : The standard deviation calculated based on the phase observation residuals of all satellites.

[0015] Preferably, the standard deviation calculated based on the phase observation residuals of all satellites (9); In formula (9): : The weighted mean value of the phase observation residuals of satellite s at frequency point i; : The weight of the phase observation of satellite s at frequency point i determined by the (j - 1)-th iterative calculation; Preferably, the weighted mean value of the phase observation residuals of satellite s at frequency point i (10).

[0016] Compared with the prior art, the beneficial effects of the present invention are: The method for determining weights of observations in precise data processing of navigation satellites provided by the present invention can determine the weights of observations through the a posteriori residuals of GNSS observations without the need for additional signal-to-noise ratio auxiliary information. By determining the weights of observations epoch by epoch for each satellite, the satellite observation information can be fully utilized, and the satellite observations of an entire arc segment can be avoided from being deleted due to poor observation quality of the satellite in some time periods. By determining weights through the a posteriori residuals of observations, the signal differences of different satellite systems can be fully considered, and the weight distribution of satellite observations of different systems can be reasonably determined. The present invention creatively realizes the fine determination of weights of observations epoch by epoch for each satellite based on the a posteriori residuals of observations, improving the performance of GNSS precise positioning and orbit determination. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a flowchart of a method for determining weights of observations in precise data processing of navigation satellites provided by the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0019] Figure 1 It is a flowchart of a method for determining weights of observations in precise data processing of navigation satellites provided by the present invention. As Figure 1 shown, the embodiments of the present invention provide a method for determining weights of observations in precise data processing of navigation satellites, including the following steps: Step 1: Construct a GNSS precise data processing observation model: Use the GNSS signal tracking equipment of global tracking stations to collect GNSS observation data, eliminate gross error data, mark phase cycle slips, establish pseudorange observation equations and phase observation equations, and solve for the estimated values of the parameters to be estimated using the least squares principle; Step 2: Determine the weights of pseudorange observations: Substitute the estimated values of the parameters to be estimated back into the pseudorange observation equation to calculate the pseudorange residuals, and calculate the weights of pseudorange observations for each satellite epoch by epoch at different levels; Step 3: Determine the weights of phase observations: Substitute the estimated values of the parameters to be estimated back into the phase observation equation to calculate the phase residuals, detect small phase cycle slips based on the phase residual sequence, calculate the mean value of the residuals for each segment of the phase residuals segmented by cycle slips and subtract it from the phase residuals to obtain the updated phase residuals, and calculate the weights of phase observations for each satellite epoch by epoch at different levels; Step 4: Based on the weights of each satellite and each epoch determined in Step 3, repeat Steps 1-3 to calculate the final precise positioning and orbit determination results through iterative calculation.

[0020] It should be noted that in the method for determining weights of observation values in precise data processing of navigation satellites provided by the present invention, it is assumed that the receiving device at the tracking station can track GNSS satellite signals, and the observables at least include pseudorange and phase. Only in this way can the observation equations for positioning and orbit determination be effectively established and the observation value residuals be calculated. In practice, this condition is very easy to meet because, from the perspective of the receiving devices at IGS global tracking stations, they are all measurement-type receivers, at least supporting signal tracking of a single satellite system, and the observation files include pseudorange and phase observables.

[0021] In an embodiment of the present invention, the pseudorange observation equation and the phase observation equation in step 1 are as follows: (1); In formula (1): and : respectively represent the pseudorange and phase measurement values; : the geometric distance between the station and the satellite; s : the satellite number; r : the receiver number; i : the frequency point number; c : the speed of light in vacuum; : the receiver clock error; : the satellite clock error; : the ionospheric delay projection function; : the zenith ionospheric delay at the station; : the tropospheric mapping function; : the zenith tropospheric delay; : the carrier phase integer ambiguity parameter; : the i th wavelength of the , : the i th pseudorange observation value receiver and phase-end hardware delay of the , : the i th phase observation value receiver and satellite-end hardware delay of the , : respectively the pseudorange and phase multipath effects and noise of the i th frequency point.

[0022] In specific precise data processing, corresponding parameters to be estimated are set according to the requirements of precise orbit determination or positioning. At the same time, according to user preferences, a dual-frequency ionosphere-free combination or a non-differenced non-combination mode can also be selected.

[0023] Further, in an embodiment of the present invention, the estimated value of the parameter to be estimated is substituted back into the pseudo-range observation equation to calculate the pseudo-range residual. The calculation method of the pseudo-range residual in step 2 is as follows: (2); In formula (2): : Pseudo-range residual.

[0024] Even further, in an embodiment of the present invention, the hierarchical calculation of the pseudo-range observation value weight for each epoch and each satellite in step 2 specifically includes: The calculation method of the pseudo-range observation value weight is: (3); In formula (3): j: Number of iterations; : The weight of the pseudo-range observation value of satellite s at frequency point i determined by the j-th iteration calculation, with the initial weight being 1; , : Empirical coefficients, set according to the number of iterations; generally, m takes the value of 10 and n takes the value of 5 in the first calculation, and 5 and 3 respectively in subsequent iteration calculations; k is the coefficient value, generally taking the value of 2 in the first calculation and 1 in subsequent iteration calculations; : Standard deviation calculated based on the residuals of all satellite pseudo-range observations.

[0025] Specifically, in an embodiment of the present invention, the standard deviation calculated based on the residuals of all satellite pseudo-range observations (4); In formula (4): : Weighted mean of the pseudo-range observation value residuals of satellite s at frequency point i; : The weight of the pseudo-range observation value of satellite s at frequency point i determined by the (j - 1)-th iteration calculation.

[0026] Specifically, in an embodiment of the present invention, the weighted mean of the pseudo-range observation value residuals of satellite s at frequency point i (5).

[0027] In an embodiment of the present invention, the calculation method of the phase residual in step 3 is as follows: (6); In formula (6): : Phase residual.

[0028] In an embodiment of the present invention, the phase small cycle slip detection based on the phase residual sequence in step 3, and calculating the residual mean value by segmenting the phase residual according to the cycle slip and subtracting it from the phase residual to obtain the updated phase residual specifically includes: (7); In formula (7): and respectively represent the updated phase residual and the residual segment mean value.

[0029] In an embodiment of the present invention, the hierarchical calculation of the phase observation value weight for each epoch and each satellite in step 2 specifically includes: The calculation method of the phase observation value weight is (8); In formula (8): : The weight of the phase observation value of satellite s at frequency point i determined by the j-th iterative calculation, and the initial weight is 1; : The standard deviation calculated based on the phase observation value residuals of all satellites.

[0030] Specifically, the standard deviation calculated based on the phase observation value residuals of all satellites (9); In formula (9): : The weighted mean value of the phase observation value residuals of satellite s at frequency point i; : The weight of the phase observation value of satellite s at frequency point i determined by the (j - 1)-th iterative calculation.

[0031] Specifically, the weighted mean value of the phase observation value residuals of satellite s at frequency point i (10).

[0032] The method for determining weights of observations in the precise data processing of navigation satellites provided by the present invention can determine the weights of observations through the a posteriori residuals of GNSS observations without additional signal-to-noise ratio auxiliary information; by determining the weights of observations for each satellite and each epoch, the satellite observation information can be fully utilized, and the satellite observations of the entire arc segment can be avoided from being deleted due to poor observation quality in some time periods of the satellite; by determining weights through the a posteriori residuals of observations, the signal differences of different satellite systems can be fully considered, and the weight distribution of satellite observations of different systems can be reasonably determined. The present invention creatively realizes the fine determination of weights of observations for each satellite and each epoch based on the a posteriori residuals of observations, improving the performance of GNSS precise positioning and orbit determination.

[0033] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An observation weight determination method for precise data processing of navigation satellites, characterized in that It includes the following steps: Step 1: Construct a GNSS precise data processing observation model: Use the GNSS signal tracking equipment of global tracking stations to collect GNSS observation data, eliminate gross error data, mark phase cycle slips, establish pseudorange observation equations and phase observation equations, and solve using the least squares principle to obtain the estimated values of the parameters to be estimated; Step 2: Determine the weight of the pseudorange observation: Substitute the estimated values of the parameters to be estimated back into the pseudorange observation equation to calculate the pseudorange residuals, and calculate the weights of the pseudorange observations level by level, epoch by epoch, and satellite by satellite; Step 3: Determine the weight of the phase observation: Substitute the estimated values of the parameters to be estimated back into the phase observation equation to calculate the phase residuals, detect small phase cycle slips based on the phase residual sequence, calculate the mean value of the residuals by segmenting the phase residuals according to cycle slips and subtract it from the phase residuals to obtain the updated phase residuals, and calculate the weights of the phase observations level by level, epoch by epoch, and satellite by satellite; Step 4: Based on the weights of each satellite and each epoch determined in Step 3, repeat Steps 1 - 3, and calculate the final precise positioning and orbit determination results through iterative calculation.

2. The weight determination method for observation values in the precise data processing of navigation satellites according to claim 1, characterized in that The pseudorange observation equation and phase observation equation described in Step 1 are as follows: (1)； In Equation (1): and : represent the pseudorange and phase measurement values, respectively; : Geometric distance between the measuring station and the satellite; s : Satellite number; r : Receiver number; i : Frequency point number; c : speed of light in vacuum; : Receiver clock error; : Satellite clock error; : Ionospheric delay projection function; : Zenith ionospheric delay at the station; : Tropospheric mapping function; : Zenith tropospheric delay; : Carrier phase integer ambiguity parameter; : The i Wavelength of the frequency point; , : The pseudorange observation value receiver and the hardware delay at the phase end of the i th frequency point; , : Phase observation value receiver and satellite-side hardware delay of the i th frequency point; , : The pseudorange and phase multipath effects and noise at the i th frequency point respectively.

3. The method for determining weights of observation values in precise data processing of navigation satellites according to claim 2, wherein, The calculation method of the pseudorange residuals described in Step 2 is: (2)； In Equation (2): : Pseudorange residual.

4. The method for determining weights of observed values in precise data processing of navigation satellites according to claim 3, characterized in that, The specific process of calculating the weights of the pseudorange observations level by level, epoch by epoch, and satellite by satellite described in Step 2 includes: The calculation method of the weights of the pseudorange observations is: (3)； In Equation (3): j: The number of iterations; : The weight of the pseudorange observation value of satellite s at frequency point i determined by the j-th iteration calculation, and the initial weight is 1; , : Empirical coefficient, which is set according to the number of iterations; : The standard deviation calculated based on the residuals of all satellite pseudorange observations.

5. The method for determining weights of observation values in precise data processing of navigation satellites according to claim 4, characterized in that The standard deviation calculated based on the residuals of all satellite pseudorange observations is calculated as follows: (4)； In Equation (4): : The weighted mean of the residual of the pseudorange observation value of satellite s frequency point i; : The weight of the pseudo-range observation value of satellite s at frequency point i determined for the (j - 1)-th iteration calculation; The weighted mean of the residual of the pseudo-range observation value of satellite s at frequency point i is calculated as follows: (5)。 6. The method for determining weights of observed values in precise data processing of navigation satellites according to claim 5, characterized in that The calculation method of the phase residuals described in Step 3 is: （6）； In Equation (6): : Phase residual.

7. An observation weight determination method for precise data processing of navigation satellites according to claim 6, characterized in that The specific process of detecting small phase cycle slips based on the phase residual sequence, calculating the mean value of the residuals by segmenting the phase residuals according to cycle slips and subtracting it from the phase residuals to obtain the updated phase residuals described in Step 3 includes: （7）； In Equation (7): and respectively represent the updated phase residual and the segmented mean of the residual.

8. The method for determining weights of observed values in precise data processing of navigation satellites according to claim 7, wherein The specific process of calculating the weights of the phase observations level by level, epoch by epoch, and satellite by satellite described in Step 2 includes: The calculation method of the weights of the phase observations is: （8）； In Equation (8): : The weight of the phase observation value of satellite s at frequency point i determined by the j-th iteration calculation, and the initial weight is 1; : Standard deviation calculated based on the residuals of all satellite phase observations.

9. The observation weight determination method for precise data processing of navigation satellites according to claim 8, wherein, The standard deviation calculated based on the residuals of all satellite phase observations is calculated as follows: （9）； In Equation (9): : The weighted mean of the residual of the satellite s frequency point i phase observation value; : The weight of the satellite s frequency point i phase observation value determined for the (j - 1)-th iteration calculation; The weighted mean of the residual of the satellite s frequency point i phase observation value The calculation method is as follows: （10）。

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