Network real-time differential positioning method and computer device

Abstract

The application provides a network real-time differential positioning method and a computer device, the method comprising: acquiring global navigation satellite system observation values of each satellite at each frequency point, the global navigation satellite system observation values comprising pseudo-range observation values and carrier phase observation values; constructing an initial observation equation according to the global navigation satellite system observation values, the initial observation equation comprising a double-difference non-combined observation equation with a first weight and a double-difference ionosphere-free combined observation equation with a second weight, wherein the first weight is greater than the second weight; performing baseline solution according to the initial observation equation to determine double-difference tropospheric delay, double-difference integer ambiguity corresponding to each frequency point of each satellite, and double-difference ionospheric delay of each satellite at the first frequency point, and updating the second weight according to the double-difference ionospheric delay of each satellite at the first frequency point to obtain a target observation equation; and performing network real-time differential positioning based on the target observation equation to improve the accuracy of the baseline solution and the positioning precision.

Description

TECHNICAL FIELD

[0001] The present application relates to the positioning technical field, in particular, relates to a network real-time differential positioning method and a computer device. BACKGROUND

[0002] The network real-time differential positioning (Network Real-time Kinematic, NRTK for short) technology obtains a baseline list based on the observation data of a reference station in real time, fixes the integer ambiguity through baseline solution, extracts the atmospheric delay including ionospheric delay and tropospheric delay, performs atmospheric modeling according to the atmospheric delay and generates Virtual Reference Station (VRS for short) data, and realizes high-precision positioning based on the VRS data. The positioning accuracy of the network RTK depends on the accuracy of the VRS data, and the accuracy of the VRS data is related to the atmospheric delay. The key to extracting the atmospheric delay is to fix the integer ambiguity.

[0003] At present, the baseline solution is usually performed by using double-difference non-combined observation equations. In general scenarios, the baseline solution scheme can obtain accurate integer ambiguity, so as to obtain accurate atmospheric delay. However, the baseline solution scheme cannot be applied to all regions. For example, the solar radiation intensity is higher in low-latitude regions close to the equator, and the electron density of the ionosphere changes more greatly than in other regions, thereby greatly affecting the propagation of Global Navigation Satellite System (GNSS for short) signals. In addition, the vertical structure of the ionosphere in low-latitude regions is different from that in middle and high-latitude regions, which reduces the applicability of the ionosphere model, and further affects the positioning accuracy. In addition, the climate in variable climate regions is easily affected by climate such as monsoon or tropical storm, so that the stability of the ionosphere is poor. When the baseline solution is performed in the above regions, the ionosphere is easily affected by the active ionosphere, which leads to incorrect ambiguity fixing, and further leads to a large error in the extraction of the atmospheric delay, reduces the accuracy of the VRS data, and affects the positioning accuracy of the network RTK in some regions.

[0004] Therefore, the baseline solution by using the double-difference non-combined observation equation in the prior art has certain limitations. SUMMARY

[0005] The present application aims at the deficiencies in the prior art, and provides a network real-time differential positioning method and a computer device, so as to solve the problem that the positioning accuracy of the network RTK in some regions is low in the prior art.

[0006] To achieve the above object, the technical scheme adopted by the embodiments of the present application is as follows:

[0007] In a first aspect, the embodiments of the present application provide a network real-time differential positioning method, the method comprising:

[0008] obtaining global navigation satellite system observation values of each satellite at each frequency point, the global navigation satellite system observation values comprising pseudo-range observation values and carrier phase observation values;

[0009] constructing an initial observation equation according to the global navigation satellite system observation values, the initial observation equation comprising a double-difference non-combination observation equation with a first weight and a double-difference ionosphere-free combination observation equation with a second weight, wherein the first weight is greater than the second weight;

[0010] performing baseline solution according to the initial observation equation to determine double-difference tropospheric delay, double-difference integer ambiguity corresponding to each frequency point of each satellite, and double-difference ionospheric delay of each satellite at the first frequency point, and updating the second weight according to the double-difference ionospheric delay of each satellite at the first frequency point to obtain a target observation equation;

[0011] performing network real-time differential positioning based on the target observation equation.

[0012] As an optional implementation manner, the constructing an initial observation equation according to the global navigation satellite system observation values comprises:

[0013] performing double-difference operation according to the global navigation satellite system observation values to obtain a double-difference non-combination observation model, constructing the double-difference non-combination observation equation and a first observation noise variance of the double-difference non-combination observation equation according to the double-difference non-combination observation model, the first observation noise variance being used to represent the first weight; the double-difference non-combination observation model comprising an expression of double-difference pseudo-range observation values and an expression of double-difference carrier phase observation values;

[0014] constructing a double-difference ionosphere-free combination observation model according to the double-difference non-combination observation model, constructing the double-difference ionosphere-free combination observation equation and a second observation noise variance of the double-difference ionosphere-free combination observation equation according to the double-difference ionosphere-free combination observation model, the second observation noise variance being used to represent the second weight; the double-difference ionosphere-free combination observation model comprising an expression of double-difference ionosphere-free combination pseudo-range observation values and an expression of double-difference ionosphere-free combination carrier phase observation values;

[0015] constructing the initial observation equation according to the double-difference non-combination observation equation, the first observation noise variance, the double-difference ionosphere-free combination observation equation, and the second observation noise variance.

[0016] As an optional implementation manner, the double-difference non-combination observation model is obtained according to the global navigation satellite system observation values, and the obtaining comprises:

[0017] The first double-difference operation is performed on each pseudo-range observation value in the global navigation satellite system observation values, and an expression of the double-difference pseudo-range observation value is obtained, wherein the expression of the double-difference pseudo-range observation value at least comprises a double-difference geometric distance, a double-difference ionospheric delay and a double-difference zenith tropospheric wet delay;

[0018] The second double-difference operation is performed on each carrier phase observation value in the global navigation satellite system observation values, and an expression of the double-difference carrier phase observation value is obtained, wherein the expression of the double-difference carrier phase observation value at least comprises the double-difference geometric distance, the double-difference ionospheric delay, the double-difference integer ambiguity and the double-difference zenith tropospheric wet delay;

[0019] The double-difference non-combination observation model is obtained according to the expression of the double-difference pseudo-range observation value and the expression of the double-difference carrier phase observation value.

[0020] As an optional implementation manner, the double-difference ionosphere-free combination observation model is constructed according to the double-difference non-combination observation model, and the constructing comprises:

[0021] The double-difference pseudo-range observation value of a first frequency point and the double-difference pseudo-range observation value of a second frequency point are determined according to the expression of the double-difference pseudo-range observation value;

[0022] The expression of a double-difference ionosphere-free combination pseudo-range observation value is determined according to the double-difference pseudo-range observation value of the first frequency point, the double-difference pseudo-range observation value of the second frequency point and a preset combination coefficient;

[0023] The double-difference carrier phase observation value of the first frequency point and the double-difference carrier phase observation value of the second frequency point are determined according to the expression of the double-difference carrier phase observation value;

[0024] The expression of a double-difference ionosphere-free combination carrier phase observation value is determined according to the double-difference carrier phase observation value of the first frequency point, the double-difference carrier phase observation value of the second frequency point and the preset combination coefficient;

[0025] The double-difference ionosphere-free combination observation model is obtained according to the expression of the double-difference ionosphere-free combination pseudo-range observation value and the expression of the double-difference ionosphere-free combination carrier phase observation value.

[0026] As an optional implementation manner, the double-difference tropospheric delay, the double-difference integer ambiguity corresponding to each frequency point of each satellite and the double-difference ionospheric delay of each satellite at the first frequency point are determined, and the determining comprises:

[0027] determining the double-difference zenith tropospheric wet delay according to the initial observation equation, and determining the double-difference tropospheric delay according to the double-difference zenith tropospheric wet delay;

[0028] performing Kalman filtering according to the initial observation equation, and determining the double-difference integer ambiguity corresponding to each frequency of each satellite by using a least square ambiguity decorrelation adjustment method;

[0029] determining the double-difference integer ambiguity and the carrier phase observation value corresponding to the first frequency of each satellite, and the double-difference integer ambiguity and the carrier phase observation value corresponding to the second frequency of each satellite;

[0030] determining the double-difference ionospheric delay of each satellite at the first frequency according to the double-difference integer ambiguity and the carrier phase observation value corresponding to the first frequency of each satellite, and the double-difference integer ambiguity and the carrier phase observation value corresponding to the second frequency of each satellite.

[0031] As an optional implementation manner, the determining the double-difference tropospheric delay according to the double-difference zenith tropospheric wet delay comprises:

[0032] determining a double-difference tropospheric projection function according to a preset tropospheric delay mapping model, and determining the double-difference tropospheric wet delay according to the double-difference tropospheric projection function and the double-difference zenith tropospheric wet delay;

[0033] determining a double-difference tropospheric dry delay according to the tropospheric delay mapping model, and taking the sum of the double-difference tropospheric dry delay and the double-difference tropospheric wet delay as the double-difference tropospheric delay.

[0034] As an optional implementation manner, the updating the second weight according to the double-difference ionospheric delay of each satellite at the first frequency comprises:

[0035] determining an ionospheric activity index of a current epoch according to the double-difference ionospheric delay of each satellite at the first frequency; the ionospheric activity index comprises an ionospheric active satellite proportion, an ionospheric delay change rate, and an ionospheric delay mean error;

[0036] determining and updating the second weight of a next epoch of the current epoch according to the ionospheric activity index.

[0037] As an optional implementation manner, the determining and updating the second weight of a next epoch of the current epoch according to the ionospheric activity index comprises:

[0038] determining a first quotient of the ionospheric active satellite proportion and a preset ionospheric active satellite proportion threshold, a second quotient of the ionospheric delay change rate and a preset ionospheric delay change rate threshold, and a third quotient of the ionospheric delay mean error and a preset ionospheric delay mean error threshold.

[0039] multiplying the first quotient, the second quotient and the third quotient to obtain a second weight of a next epoch of the current epoch, and updating the second weight of the current epoch as the second weight of the next epoch of the current epoch.

[0040] As an optional implementation, the determining and updating the second weight of the next epoch of the current epoch according to the ionospheric activity index comprises:

[0041] If the ionospheric active satellite proportion is greater than a preset ionospheric active satellite proportion threshold, the ionospheric delay change rate is greater than a preset ionospheric delay change rate threshold, and the ionospheric delay mean error is greater than a preset ionospheric delay mean error threshold, it is determined that the ionosphere is in an active period, and a first difference between the ionospheric active satellite proportion and the preset ionospheric active satellite proportion threshold, a second difference between the ionospheric delay change rate and the preset ionospheric delay change rate threshold, and a third difference between the ionospheric delay mean error and the preset ionospheric delay mean error threshold are determined, and the second weight of the next epoch of the current epoch is determined and updated according to the first difference, the second difference and the third difference;

[0042] Otherwise, it is determined that the ionosphere is in a calm period, and the second weight of the current epoch is updated as the second weight of the next epoch of the current epoch.

[0043] In a second aspect, an embodiment of the present application provides a network real-time difference positioning device, and the device comprises:

[0044] The acquisition module is configured to acquire global navigation satellite system observation values of each satellite at each frequency point, wherein the global navigation satellite system observation values comprise pseudo-range observation values and carrier phase observation values.

[0045] The construction module is configured to construct an initial observation equation according to the global navigation satellite system observation values, wherein the initial observation equation comprises a double-difference non-combined observation equation with a first weight and a double-difference ionosphere-free combined observation equation with a second weight, and the first weight is greater than the second weight.

[0046] The determination module is configured to perform baseline solution according to the initial observation equation, to determine a double-difference tropospheric delay, a double-difference integer ambiguity corresponding to each frequency point of each satellite, and a double-difference ionospheric delay of each satellite at a first frequency point, and to update the second weight according to the double-difference ionospheric delay of each satellite at the first frequency point to obtain a target observation equation.

[0047] The positioning module is configured to perform network real-time difference positioning based on the target observation equation.

[0048] As an optional implementation, the construction module is specifically configured to:

[0049] According to the global navigation satellite system observation value, a double difference operation is performed to obtain a double difference non-combination observation model, and according to the double difference non-combination observation model, the double difference non-combination observation equation and a first observation noise variance of the double difference non-combination observation equation are constructed, and the first observation noise variance is used to represent the first weight; the double difference non-combination observation model includes an expression of double difference pseudo-range observation value and an expression of double difference carrier phase observation value;

[0050] According to the double difference non-combination observation model, the double difference ionosphere-free combination observation model is constructed, and according to the double difference ionosphere-free combination observation model, the double difference ionosphere-free combination observation equation and a second observation noise variance of the double difference ionosphere-free combination observation equation are constructed, and the second observation noise variance is used to represent the second weight; the double difference ionosphere-free combination observation model includes an expression of double difference ionosphere-free combination pseudo-range observation value and an expression of double difference ionosphere-free combination carrier phase observation value;

[0051] According to the double difference non-combination observation equation, the first observation noise variance, the double difference ionosphere-free combination observation equation and the second observation noise variance, the initial observation equation is constructed.

[0052] As an optional implementation manner, the construction module is specifically configured to:

[0053] A first double difference operation is performed on each pseudo-range observation value in the global navigation satellite system observation value to obtain the expression of the double difference pseudo-range observation value, and the expression of the double difference pseudo-range observation value at least includes double difference geometric distance, double difference ionosphere delay and double difference zenith troposphere wet delay;

[0054] A second double difference operation is performed on each carrier phase observation value in the global navigation satellite system observation value to obtain the expression of the double difference carrier phase observation value, and the expression of the double difference carrier phase observation value at least includes the double difference geometric distance, the double difference ionosphere delay, the double difference integer ambiguity and the double difference zenith troposphere wet delay;

[0055] According to the expression of the double difference pseudo-range observation value and the expression of the double difference carrier phase observation value, the double difference non-combination observation model is obtained.

[0056] As an optional implementation manner, the construction module is specifically configured to:

[0057] According to the expression of the double difference pseudo-range observation value, the double difference pseudo-range observation value of the first frequency point and the double difference pseudo-range observation value of the second frequency point are determined;

[0058] determine an expression of a double-difference ionosphere-free combined pseudo-range observation value according to the double-difference pseudo-range observation value of the first frequency point, the double-difference pseudo-range observation value of the second frequency point, and a preset combination coefficient;

[0059] determine a double-difference carrier phase observation value of the first frequency point and a double-difference carrier phase observation value of the second frequency point according to the expression of the double-difference carrier phase observation value;

[0060] determine an expression of a double-difference ionosphere-free combined carrier phase observation value according to the double-difference carrier phase observation value of the first frequency point, the double-difference carrier phase observation value of the second frequency point, and the preset combination coefficient;

[0061] obtain the double-difference ionosphere-free combined observation model according to the expression of the double-difference ionosphere-free combined pseudo-range observation value and the expression of the double-difference ionosphere-free combined carrier phase observation value.

[0062] As an optional implementation manner, the determining module is specifically configured to:

[0063] determine the double-difference zenith tropospheric wet delay according to the initial observation equation, and determine the double-difference tropospheric delay according to the double-difference zenith tropospheric wet delay;

[0064] perform Kalman filtering according to the initial observation equation, and determine the double-difference integer ambiguity and the carrier phase observation value corresponding to each frequency point of each satellite by using a least square ambiguity resolution adjustment method;

[0065] determine the double-difference integer ambiguity and the carrier phase observation value corresponding to the first frequency point of each satellite, and the double-difference integer ambiguity and the carrier phase observation value corresponding to the second frequency point of each satellite;

[0066] determine the double-difference ionospheric delay of each satellite at the first frequency point according to the double-difference integer ambiguity and the carrier phase observation value corresponding to the first frequency point of each satellite, and the double-difference integer ambiguity and the carrier phase observation value corresponding to the second frequency point of each satellite.

[0067] As an optional implementation manner, the determining module is specifically configured to:

[0068] determine a double-difference tropospheric projection function according to a preset tropospheric delay mapping model, and determine a double-difference tropospheric wet delay according to the double-difference tropospheric projection function and the double-difference zenith tropospheric wet delay;

[0069] determine a double-difference tropospheric dry delay according to the tropospheric delay mapping model, and take a sum of the double-difference tropospheric dry delay and the double-difference tropospheric wet delay as the double-difference tropospheric delay.

[0070] As an optional implementation manner, the determining module is specifically configured to:

[0071] Based on the double-difference ionospheric delay of each satellite at the first frequency point, the ionospheric activity index of the current epoch is determined; the ionospheric activity index includes the proportion of ionospherically active satellites, the rate of change of ionospheric delay, and the mean square error of ionospheric delay;

[0072] Based on the ionospheric activity index, determine and update the second weight of the next epoch of the current epoch.

[0073] As an optional implementation, the determining module is specifically used for:

[0074] The first quotient of the proportion of active ionospheric satellites to a preset threshold for the proportion of active ionospheric satellites, the second quotient of the rate of change of ionospheric delay to a preset threshold for the rate of change of ionospheric delay, and the third quotient of the mean square error of ionospheric delay to a preset threshold for the mean square error of ionospheric delay are determined.

[0075] The product of the first quotient, the second quotient, and the third quotient is used as the second weight of the next epoch of the current epoch, and the second weight of the current epoch is updated in the next epoch of the current epoch.

[0076] As an optional implementation, the determining module is specifically used for:

[0077] If the proportion of active ionospheric satellites is greater than a preset threshold for the proportion of active ionospheric satellites, the rate of change of ionospheric delay is greater than a preset threshold for the rate of change of ionospheric delay, and the mean square error of ionospheric delay is greater than a preset threshold for the mean square error of ionospheric delay, then the ionosphere is determined to be in an active period. A first difference between the proportion of active ionospheric satellites and the preset threshold for the proportion of active ionospheric satellites, a second difference between the rate of change of ionospheric delay and the preset threshold for the rate of change of ionospheric delay, and a third difference between the mean square error of ionospheric delay and the preset threshold for the mean square error of ionospheric delay are determined. Based on the first difference, the second difference, and the third difference, the second weight of the next epoch of the current epoch is determined and updated.

[0078] Otherwise, determine that the ionosphere is in a quiescent period, and use the second weight of the current epoch as the second weight of the next epoch.

[0079] Thirdly, embodiments of this application provide a computer device, including: a processor, a memory, and a bus. The memory stores machine-readable instructions executable by the processor. When the computer device is running, the processor communicates with the memory via the bus, and the processor executes the machine-readable instructions to perform the steps of the network real-time differential positioning method as described in the first aspect above.

[0080] In a fourth aspect, the embodiments of the present application provide a computer readable storage medium, which stores a computer program. When the computer program is run by a processor, the steps of the network real-time differential positioning method according to the first aspect are executed.

[0081] The present application has the following beneficial effects:

[0082] The present application provides a network real-time differential positioning method and a computer device. Global navigation satellite system observation values of each satellite at each frequency point are received, including pseudo-range observation values and carrier phase observation values. According to the global navigation satellite system observation values of each satellite at each frequency point, an initial observation equation is constructed based on a double-difference non-combined observation model and a double-difference ionosphere-free combined observation model, including a double-difference non-combined observation equation with a larger first weight and a double-difference ionosphere-free combined observation equation with a smaller second weight. According to the double-difference non-combined observation equation with the larger first weight and the double-difference ionosphere-free combined observation equation with the smaller second weight in the initial observation equation, baseline calculation of an initial epoch is mainly dependent on the double-difference non-combined observation equation in the initial observation equation, so as to determine double-difference tropospheric delay, double-difference integer ambiguity corresponding to each frequency point of each satellite, and double-difference ionospheric delay of each satellite at a first frequency point. The second weight of the double-difference ionosphere-free combined observation equation is updated based on the ionospheric activity of the region to be positioned under the current climate condition represented by the double-difference ionospheric delay of each satellite at the first frequency point, so as to obtain a target observation equation. Baseline calculation is performed again based on the target observation equation, so as to determine atmospheric delay and perform atmospheric modeling on baseline atmospheric delay around the approximate coordinates, so as to generate virtual rover data and send the virtual rover data to a user terminal, thereby realizing high-precision network real-time differential positioning. By adding the double-difference ionosphere-free combined observation model to the double-difference non-combined observation model, the double-difference non-combined observation equation with the first weight and the double-difference ionosphere-free combined observation equation with the second weight are combined to form an observation equation and participate in baseline calculation. The weight of the double-difference ionosphere-free combined observation equation in the observation equation is adjusted in real time and adaptively according to the ionospheric activity, so that the baseline calculation is more dependent on the double-difference non-combined observation equation in the ionosphere quiet period with low ionospheric activity, thereby avoiding amplification of observation value noise and multipath error. In the ionosphere active period with high ionospheric activity, the baseline calculation is more dependent on the double-difference ionosphere-free combined observation equation, so as to eliminate ionospheric error. The ionosphere can be constrained to obtain correct integer ambiguity, improve the accuracy of extracting atmospheric delay, and further improve the positioning accuracy of the network real-time differential positioning in low-latitude regions or regions with variable climate. BRIEF DESCRIPTION OF DRAWINGS

[0083] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some of the embodiments of the present application, and therefore should not be regarded as a limitation on the scope, and for those of ordinary skill in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0084] Figure 1 The flowchart of the network real-time differential positioning method provided by the embodiments of the present application is shown in the figure.

[0085] Figure 2 The flowchart of the network real-time differential positioning method provided by the embodiments of the present application is shown in the figure.

[0086] Figure 3 The flowchart of the network real-time differential positioning method provided by the embodiments of the present application is shown in the figure.

[0087] Figure 4 The flowchart of the network real-time differential positioning method provided by the embodiments of the present application is shown in the figure.

[0088] Figure 5 The flowchart of the network real-time differential positioning method provided by the embodiments of the present application is shown in the figure.

[0089] Figure 6 The flowchart of the network real-time differential positioning method provided by the embodiments of the present application is shown in the figure.

[0090] Figure 7 The flowchart of the network real-time differential positioning method provided by the embodiments of the present application is shown in the figure.

[0091] Figure 8 The flowchart of the network real-time differential positioning method provided by the embodiments of the present application is shown in the figure.

[0092] Figure 9 The flowchart of the network real-time differential positioning method provided by the embodiments of the present application is shown in the figure.

[0093] Figure 10 The module structure diagram of the network real-time differential positioning device provided by the embodiments of the present application is shown in the figure.

[0094] Figure 11 The structure diagram of the computer device provided by the embodiments of the present application is shown in the figure. DETAILED DESCRIPTION

[0095] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the following will be combined with the accompanying drawings for the embodiments of the present application to make a clear and complete description of the technical solutions in the embodiments of the present application. It should be understood that the accompanying drawings in the present application are only for the purpose of illustration and description, and are not used to limit the scope of the present application. In addition, it should be understood that the schematic drawings are not drawn according to the actual proportions. The flowcharts used in the present application show the operations implemented according to some embodiments of the present application. It should be understood that the operations of the flowcharts can not be implemented in sequence, and the steps without logical context relationship can be reversed in sequence or implemented simultaneously. In addition, one or more other operations can be added to the flowcharts or one or more operations can be removed from the flowcharts under the guidance of the content of the present application.

[0096] In addition, the described embodiments are only some of the embodiments of the present application, not all the embodiments. The components of the embodiments of the present application described and shown in the accompanying drawings can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0097] It should be noted that the term "comprising" will be used in the embodiments of the present application to indicate the presence of the features declared thereafter, but does not exclude the addition of other features.

[0098] Currently, network RTK usually adopts double-difference non-combined observation equation for baseline solution. For low-latitude areas close to the equator, the intensity of solar radiation is higher than that in middle and high latitude areas, and the electron density of ionosphere changes more greatly, thereby having greater influence on the propagation of GNSS signals. In addition, the vertical structure of ionosphere in low-latitude areas is different from that in middle and high latitude areas, which reduces the applicability of the ionosphere model, and further affects the positioning accuracy. In addition, the stability of ionosphere in areas with variable climate is poor. When performing baseline solution in low-latitude areas or areas with variable climate, the ambiguity is easily affected by the active ionosphere, resulting in fixing error, which affects the positioning accuracy of network RTK in low-latitude areas or areas with variable climate.

[0099] The embodiment of the application proposes a network real-time differential positioning method based on the above problems. The double-difference non-combined observation model is added with a double-difference ionosphere-free combined observation model. The double-difference non-combined observation equation with a first weight and the double-difference ionosphere-free combined observation equation with a second weight are used to form an observation equation and participate in baseline solution to obtain tropospheric delay, integer ambiguity and ionospheric delay. The weight of the double-difference ionosphere-free combined observation equation in the observation equation is adjusted in real time according to the activity of the ionosphere to constrain the ionosphere to obtain correct integer ambiguity and then obtain correct atmospheric delay, thereby improving the positioning accuracy of the network real-time differential positioning in low-latitude areas or areas with variable climate.

[0100] Figure 1 A flowchart of the network real-time differential positioning method provided by the embodiment of the application is shown in the figure. The execution subject of the method can be any computer device with computing processing capability. As shown in the figure, the method comprises the following steps. Figure 1

[0101] S101, global navigation satellite system observation values of each satellite at each frequency point are obtained. The global navigation satellite system observation values comprise pseudo-range observation values and carrier phase observation values.

[0102] Optionally, a plurality of reference stations are established to form a reference station network. Each of the plurality of reference stations serves as a receiver to receive global navigation satellite system signals of each satellite at each frequency point in real time to obtain GNSS observation values of each satellite at each frequency point. Each reference station transmits the GNSS observation values of each satellite at each frequency point to a computer device of a data processing center in real time. The GNSS observation values comprise pseudo-range observation values P i and carrier phase observation values φ i .

[0103] The GNSS signals from the satellite end to the receiver end are disturbed by satellite end errors, propagation path errors and receiver end errors. The satellite end errors comprise satellite clock errors, satellite end hardware delays and orbit delays. The propagation path errors comprise ionospheric delays, tropospheric delays and multipath errors. The receiver end errors comprise receiver clock errors, receiver end hardware delays and relativistic effects.

[0104] The pseudo-range observation value P i is a measured distance obtained by multiplying the propagation time of the GNSS signals transmitted by the satellite and reaching the receiver antenna by the speed of light. Due to the clock errors and atmospheric refraction delays, the distance is not the true distance. The carrier phase observation value φ i ​The phase difference between the satellite carrier signal received by the receiver and the reference carrier signal generated by the receiver oscillator, i is an arbitrary frequency point.

[0105] S102, according to the global navigation satellite system observation value, the initial observation equation is constructed, the initial observation equation includes the double difference non-combination observation equation with the first weight and the double difference ionosphere-free combination observation equation with the second weight, wherein the first weight is greater than the second weight.

[0106] Optionally, the computer equipment of the data processing center obtains the baseline list according to the coordinates of each reference station in the Delaunay triangulation, and constructs the initial observation equation based on the double difference non-combination observation model and the double difference ionosphere-free combination observation model according to the GNSS observation values of each satellite at each frequency point. Wherein, the initial observation equation includes the double difference non-combination observation equation with the first weight and the double difference ionosphere-free combination observation equation with the second weight, and the first weight is greater than the second weight.

[0107] That is, before the baseline solution at the starting epoch, the weight of the double difference non-combination observation equation in the constructed initial observation equation is greater than the weight of the double difference ionosphere-free combination observation equation, so that the baseline solution at the starting epoch is mainly dependent on the double difference non-combination observation equation in the initial observation equation. Wherein, the starting epoch is a specific time in GNSS, as a reference point for time measurement and time epoch information.

[0108] S103, according to the initial observation equation, the baseline solution is carried out, the double difference tropospheric delay, the double difference integer ambiguity corresponding to each frequency point of each satellite and the double difference ionospheric delay of each satellite at the first frequency point are determined, and the second weight is updated according to the double difference ionospheric delay of each satellite at the first frequency point, to obtain the target observation equation.

[0109] Optionally, the double difference non-combination observation equation with the larger first weight and the double difference ionosphere-free combination observation equation with the smaller second weight in the initial observation equation are solved simultaneously, and the baseline solution at the starting epoch is mainly dependent on the double difference non-combination observation equation in the initial observation equation, to determine the double difference tropospheric delay and the double difference integer ambiguity corresponding to each frequency point of each satellite and according to the double difference integer ambiguity corresponding to each frequency point of each satellite extract the double difference ionospheric delay of each satellite at the first frequency point Wherein, i is an arbitrary frequency point, and n is an arbitrary satellite.

[0110] The double difference ionospheric delay of each satellite at the first frequency point characterizing the ionospheric activity level of the region to be positioned under current climatic conditions, updating the second weight of the double-difference ionosphere-free combined observation equation at the next epoch of the starting epoch, obtaining a target observation equation, and performing baseline solution based on the target observation equation at the next epoch of the starting epoch, and updating the second weight of the double-difference ionosphere-free combined observation equation at each subsequent epoch according to the double-difference ionospheric delay of each satellite at the first frequency point solved at the previous epoch characterizing the ionospheric activity level of the region to be positioned under current climatic conditions, updating the second weight of the double-difference ionosphere-free combined observation equation at the next epoch of the starting epoch, obtaining a target observation equation, and performing baseline solution based on the target observation equation at the next epoch of the starting epoch, and updating the second weight of the double-difference ionosphere-free combined observation equation at each subsequent epoch according to the double-difference ionospheric delay of each satellite at the first frequency point solved at the previous epoch real-time iterative updating of the second weight of the double-difference ionosphere-free combined observation equation, thereby obtaining a new target observation equation. Wherein, the ionospheric activity level is positively correlated with the second weight of the double-difference ionosphere-free combined observation equation, that is, the higher the ionospheric activity level, the greater the second weight of the double-difference ionosphere-free combined observation equation, so that in the baseline solution process at the next epoch of the current epoch, the double-difference ionosphere-free combined observation equation in the target observation equation is more relied on. The lower the ionospheric activity level, the smaller the second weight of the double-difference ionosphere-free combined observation equation, so that in the baseline solution process at the next epoch of the current epoch, the double-difference non-combined observation equation in the target observation equation is more relied on.

[0111] It is worth noting that the double-difference ionosphere-free combined observation equation can eliminate the influence of ionospheric activity, but at the same time it will amplify the noise and multipath error of the observation value. In the ionosphere quiet period with low ionospheric activity level, the amplification of the noise and multipath error of the observation value will bring major negative effects to the baseline solution. While in the ionosphere active period with high ionospheric activity level, compared with the noise and multipath error of the observation value, the ionospheric delay error will bring major negative effects to the baseline solution, at this time the amplification of the noise and multipath error of the observation value is acceptable.

[0112] By setting the ionospheric activity level to be positively correlated with the second weight of the double-difference ionosphere-free combined observation equation, it is achieved that in the ionosphere quiet period with low ionospheric activity level, the baseline solution relies more on the double-difference non-combined observation equation in the target observation equation, avoiding the amplification of the noise and multipath error of the observation value. In the ionosphere active period with high ionospheric activity level, the baseline solution relies more on the double-difference ionosphere-free combined observation equation in the target observation equation, so as to eliminate the ionospheric error.

[0113] S104, performing network real-time differential positioning based on the target observation equation.

[0114] Optionally, performing baseline solution based on the target observation equation updated iteratively at each epoch, extracting the double-difference tropospheric delay and the double-difference ionospheric delay of each satellite at the first frequency point according to the double-difference tropospheric delay and double-difference ionospheric delay of each satellite at the first frequency The atmospheric delay is determined. The computer device of the data processing center performs atmospheric modeling on the baseline atmospheric delay around the rough coordinates uploaded by the user through the terminal, generates VRS data at the location of the user, and issues the VRS data to the user terminal, thereby realizing high-precision positioning of the network RTK.

[0115] In this embodiment, global navigation satellite system observations of each satellite at each frequency point sent by each reference station are received, including pseudo-range observations and carrier phase observations. Based on the global navigation satellite system observations of each satellite at each frequency point, an initial observation equation including a double-difference non-combination observation equation with a larger first weight and a double-difference ionosphere-free combination observation equation with a smaller second weight is constructed based on a double-difference non-combination observation model and a double-difference ionosphere-free combination observation model. The baseline solution at the initial epoch is mainly dependent on the double-difference non-combination observation equation in the initial observation equation according to the double-difference non-combination observation equation with a larger first weight and the double-difference ionosphere-free combination observation equation with a smaller second weight in the initial observation equation, and the double-difference tropospheric delay, the double-difference integer ambiguity corresponding to each frequency point of each satellite, and the double-difference ionospheric delay of each satellite at the first frequency point are determined. Based on the ionospheric activity of the region to be positioned under the current climate condition represented by the double-difference ionospheric delay of each satellite at the first frequency point, the second weight of the double-difference ionosphere-free combination observation equation is updated to obtain a target observation equation. The baseline solution is performed again based on the target observation equation to determine the atmospheric delay, and atmospheric modeling is performed on the baseline atmospheric delay around the rough coordinates to generate virtual reference station data and issue the virtual reference station data to the user terminal, thereby realizing high-precision network real-time differential positioning. By adding the double-difference ionosphere-free combination observation model to the double-difference non-combination observation model, the observation equation is composed of the double-difference non-combination observation equation with the first weight and the double-difference ionosphere-free combination observation equation with the second weight and participates in the baseline solution, and the weight of the double-difference ionosphere-free combination observation equation in the observation equation is adjusted in real time according to the ionospheric activity, so that the baseline solution relies more on the double-difference non-combination observation equation in the ionosphere quiet period with low ionospheric activity, thereby avoiding amplification of the noise and multipath error of the observation value. In the ionosphere active period with high ionospheric activity, the baseline solution relies more on the double-difference ionosphere-free combination observation equation to eliminate ionospheric errors. The ionosphere can be constrained to obtain correct integer ambiguity, improve the accuracy of extracting atmospheric delay, and further improve the positioning accuracy of network real-time differential positioning in low-latitude regions or regions with variable climate.

[0116] Hereinafter, the process of constructing the initial observation equation according to the global navigation satellite system observations will be described in detail.

[0117] Figure 2A flowchart of constructing an initial observation equation of a network real-time differential positioning method provided by an embodiment of the present application is shown in FIG. 1. Figure 2 The step of constructing an initial observation equation according to each global navigation satellite system observation value in step S102 includes:

[0118] S201, performing double-difference operation according to global navigation satellite system observation values to obtain a double-difference non-combined observation model, constructing a double-difference non-combined observation equation and a first observation noise variance of the double-difference non-combined observation equation according to the double-difference non-combined observation model, and the first observation noise variance being used to represent a first weight; the double-difference non-combined observation model includes an expression of double-difference pseudorange observation values and an expression of double-difference carrier phase observation values.

[0119] Optionally, since GNSS signals from a satellite end to a receiver end are interfered by satellite end errors, propagation path errors and receiver end errors, taking one satellite as an example, the pseudorange observation value P i and the carrier phase observation value φ i in each frequency point of GNSS observation values are expressed based on the following formulas (1) and (2):

[0120]

[0121] wherein P i is a pseudorange observation value of the i-th frequency point, φ i is a carrier phase observation value of the i-th frequency point, ρ is a geometric distance from the satellite to the receiver, c is the speed of light, dt s is a satellite clock error, dt r is a receiver clock error, T is a troposphere delay, I is an ionosphere delay of the first frequency point, μ i is a ratio coefficient of the ionosphere delay of the i-th frequency point and the ionosphere delay of the first frequency point, μ i I is an ionosphere delay of the i-th frequency point, λ i is a wavelength of the i-th frequency point of GNSS signals, N i is an integer ambiguity of the carrier phase observation value of the i-th frequency point, δP i,r is a hardware delay of the pseudorange observation value of the i-th frequency point at the receiver end, is a hardware delay of the pseudorange observation value of the i-th frequency point at the satellite end, ∈ pi is a pseudorange observation noise of the i-th frequency point, ∈ Li is a carrier phase observation noise of the i-th frequency point.

[0122] According to the pseudorange observation value P i and the carrier phase observation value φ i, the satellite clock error, the receiver clock error and the hardware delay are eliminated by double difference operation, a double difference non-combined observation model shown in the following formula (3) is constructed, including the expression of the double difference pseudo-range observation value above and the expression of the double difference carrier phase observation value below:

[0123]

[0124] wherein, is the double difference pseudo-range observation value of the i-th frequency point, is the double difference geometric distance from the satellite to the receiver, is the double difference ionospheric delay of the first frequency point, is the double difference ionospheric delay of the i-th frequency point, is the double difference tropospheric dry delay, is the double difference tropospheric projection function, is the double difference zenith tropospheric wet delay, is the double difference pseudo-range observation noise of the i-th frequency point, is the double difference carrier phase observation value of the i-th frequency point, λ i is the wavelength of the i-th frequency point of the GNSS signal, is the double difference integer ambiguity of the carrier phase observation value of the i-th frequency point, is the double difference carrier phase observation noise of the i-th frequency point.

[0125] Since the double difference geometric distance from the satellite to the receiver can be obtained by calculating the distance between the known reference station (receiver) coordinates and the satellite coordinates, the double difference tropospheric dry delay and the double difference tropospheric projection function can also be obtained by calculation, then the estimated parameters in the double difference non-combined observation model are the double difference integer ambiguity, the double difference ionospheric delay and the double difference zenith tropospheric wet delay. Based on the double difference non-combined observation model shown in the above formula (3), the following formula (4) is derived:

[0126]

[0127] wherein:

[0128]

[0129] wherein, S represents a satellite, n is the number of satellites, i and j represent different frequency points, and are the carrier phase observation value and the pseudo-range observation value of each satellite at the i-th frequency point and the j-th frequency point, is the double difference ionospheric delay of each satellite at the first frequency point, and is the double-difference integer ambiguity of carrier phase observation of each satellite at the i-th frequency and the j-th frequency, and λ i and λ j are the wavelength of GNSS signal at the i-th frequency and the j-th frequency, respectively, is the double-difference zenith tropospheric wet delay, is the double-difference tropospheric dry delay, and μ i and μ j are the ratio coefficients of ionospheric delay at the i-th frequency and the j-th frequency to the ionospheric delay at the first frequency, respectively, is the double-difference tropospheric projection function of each satellite.

[0130] Based on the double-difference non-combination observation model shown in the above formula (3) and the double-difference non-combination observation equation shown in the above formula (4), the first observation noise variance R k of the double-difference non-combination observation equation is derived as follows: k

[0131]

[0132] wherein R k is the first observation noise variance of the double-difference non-combination observation equation, which can represent the first weight of the double-difference non-combination observation equation when filtering in the initial observation equation, and are the variances of the pseudo-range observation noise of each satellite at the i-th frequency and the j-th frequency, respectively, and are the variances of the carrier phase observation noise of each satellite at the i-th frequency and the j-th frequency, respectively.

[0133] S202, according to the double-difference non-combination observation model, a double-difference ionosphere-free combination observation model is constructed, and a double-difference ionosphere-free combination observation equation and a second observation noise variance of the double-difference ionosphere-free combination observation equation are constructed according to the double-difference ionosphere-free combination observation model, the second observation noise variance is used to represent the second weight; the double-difference ionosphere-free combination observation model includes an expression of double-difference ionosphere-free combination pseudo-range observation value and an expression of double-difference ionosphere-free combination carrier phase observation value.

[0134] Optionally, according to the double-difference non-combination observation model shown in the above formula (3), by eliminating the influence of the first-order ionospheric delay error, a double-difference ionosphere-free combination observation model shown in the following formula (6) is constructed, including the above expression of double-difference ionosphere-free combination pseudo-range observation value and the following expression of double-difference ionosphere-free combination carrier phase observation value:

[0135]

[0136] wherein,​ is a double-difference ionosphere-free combined pseudorange observation, is a double-difference geometry range from satellite to receiver, is a double-difference troposphere dry delay, is a double-difference troposphere mapping function, is a double-difference zenith troposphere wet delay, is a double-difference ionosphere-free combined pseudorange observation noise, is a double-difference ionosphere-free combined carrier phase observation, λ1 and λ2 are the wavelengths of the first and second frequency points of GNSS signals respectively, is a first coefficient in the preset combination coefficient, is a second coefficient in the preset combination coefficient, is the square of the frequency corresponding to the first frequency point, is the square of the frequency corresponding to the second frequency point, and are double-difference integer ambiguities of the double-difference carrier phase observations of the first and second frequency points respectively, is a double-difference ionosphere-free combined carrier phase observation noise.

[0137] Based on the double-difference ionosphere-free combined observation model shown in the above formula (6), a double-difference ionosphere-free combined observation equation shown in the following formula (7) is derived:

[0138]

[0139] wherein n is the number of satellites, i and j represent different frequency points, and are double-difference integer ambiguities of the double-difference carrier phase observations of the first and second frequency points respectively, λ1 and λ2 are the wavelengths of the first and second frequency points of GNSS signals respectively, is a double-difference zenith troposphere wet delay, is a double-difference troposphere dry delay, is a double-difference troposphere mapping function of each satellite.

[0140] Based on the double-difference ionosphere-free combined observation model shown in the above formula (6) and the double-difference ionosphere-free combined observation equation shown in the above formula (7), a second observation noise variance R kIF of the double-difference ionosphere-free combined observation equation is derived as follows: kIF

[0141]

[0142] wherein R kIF ​The second observation noise variance of the double-difference ionosphere-free combined observation equation can represent the second weight of the double-difference ionosphere-free combined observation equation when filtering in the initial observation equation, The variance of the pseudorange observation noise of each satellite, The variance of the carrier phase observation noise of each satellite.

[0143] S203, constructing an initial observation equation according to the double-difference non-combined observation equation, the first observation noise variance of the double-difference non-combined observation equation, the double-difference ionosphere-free combined observation equation, and the second observation noise variance of the double-difference ionosphere-free combined observation equation.

[0144] Optionally, the initial observation equation is constructed according to the double-difference non-combined observation equation shown in the above formula (4), the first observation noise variance R k of the double-difference non-combined observation equation shown in the formula (5), the double-difference ionosphere-free combined observation equation shown in the formula (7), and the second observation noise variance R kIF of the double-difference ionosphere-free combined observation equation shown in the formula (8). Wherein, the first observation noise variance R k represented in the initial observation equation is much larger than the second observation noise variance R kIF represented, so that when filtering and solving the initial observation equation, the double-difference non-combined observation equation shown in the formula (4) is mainly relied on.

[0145] In the embodiment, the double-difference non-combined observation model including the expression of the double-difference pseudorange observation value and the expression of the double-difference carrier phase observation value is obtained by performing double-difference operation on the global navigation satellite system observation values, and the double-difference non-combined observation equation and the first observation noise variance of the double-difference non-combined observation equation are constructed according to the double-difference non-combined observation model. According to the double-difference non-combined observation model, the double-difference ionosphere-free combined observation model including the expression of the double-difference ionosphere-free combined pseudorange observation value and the expression of the double-difference ionosphere-free combined carrier phase observation value is constructed by eliminating the influence of the first-order ionospheric delay error, and the double-difference ionosphere-free combined observation equation and the second observation noise variance of the double-difference ionosphere-free combined observation equation are constructed according to the double-difference ionosphere-free combined observation model. The initial observation equation is constructed according to the double-difference non-combined observation equation, the first observation noise variance of the double-difference non-combined observation equation, the double-difference ionosphere-free combined observation equation, and the second observation noise variance of the double-difference ionosphere-free combined observation equation. The error influence of the ionospheric delay is suppressed so as to improve the accuracy of ambiguity fixing.

[0146] Hereinafter, the process of performing double-difference operation according to each global navigation satellite system observation value to obtain the double-difference non-combined observation model is described in detail.

[0147] Figure 3A flowchart of a process for obtaining a double-difference non-combined observation model of a network real-time differential positioning method provided by an embodiment of the present application is shown in FIG. 26. Figure 3 The step S201 of performing double-difference operation on global navigation satellite system observation values to obtain a double-difference non-combined observation model includes the following steps.

[0148] S301, performing first double-difference operation on each pseudorange observation value in the global navigation satellite system observation values to obtain an expression of double-difference pseudorange observation values, the expression of double-difference pseudorange observation values including at least double-difference geometric distance, double-difference ionospheric delay, and double-difference zenith tropospheric wet delay.

[0149] Optionally, performing first double-difference operation on each pseudorange observation value P i in the GNSS observation values of each satellite at each frequency point to obtain an initial expression of double-difference pseudorange observation values , which is represented by the following formula (9).

[0150]

[0151] wherein, P is the double-difference pseudorange observation value at the i-th frequency point, is the double-difference geometric distance from the satellite to the receiver, is the double-difference ionospheric delay at the first frequency point, is the double-difference ionospheric delay at the i-th frequency point, is the double-difference tropospheric delay, is the double-difference pseudorange observation noise at the i-th frequency point.

[0152] The double-difference tropospheric delay includes a double-difference tropospheric dry delay and a double-difference tropospheric wet delay The double-difference tropospheric wet delay is the product of a double-difference tropospheric mapping function and a double-difference zenith tropospheric wet delay The double-difference tropospheric delay and the double-difference tropospheric wet delay are represented by the following formula (10) and formula (11).

[0153]

[0154] wherein, is the double-difference tropospheric delay, is the double-difference tropospheric dry delay, is the double-difference tropospheric wet delay, is the double-difference tropospheric mapping function, is the double-difference zenith tropospheric wet delay.

[0155] Substitute the above formula (10) and formula (11) into the above formula (9), to obtain the expression of the double-difference pseudo-range observation value , so that the expression of the double-difference pseudo-range observation value at least includes the double-difference geometric distance from the satellite to the receiver , the double-difference ionospheric delay, and the double-difference zenith tropospheric wet delay The double-difference pseudo-range observation value is represented based on the following formula (12)

[0156]

[0157] wherein, is the double-difference pseudo-range observation value at the i-th frequency point, is the double-difference geometric distance from the satellite to the receiver, is the double-difference ionospheric delay at the first frequency point, is the double-difference ionospheric delay at the i-th frequency point, is the double-difference tropospheric dry delay, is the double-difference tropospheric projection function, is the double-difference zenith tropospheric wet delay, is the double-difference pseudo-range observation noise at the i-th frequency point.

[0158] S302, performing second double-difference operation on each carrier phase observation value in the global navigation satellite system observation value, to obtain the expression of the double-difference carrier phase observation value, and the expression of the double-difference carrier phase observation value at least includes the double-difference geometric distance, the double-difference ionospheric delay, the double-difference integer ambiguity, and the double-difference zenith tropospheric wet delay.

[0159] Optionally, performing second double-difference operation on each carrier phase observation value φ i in the GNSS observation value at each frequency point of each satellite, to obtain the initial expression of the double-difference carrier phase observation value , and the double-difference carrier phase observation value is represented based on the following formula (13)

[0160]

[0161] wherein, is the double-difference carrier phase observation value at the i-th frequency point, is the double-difference geometric distance from the satellite to the receiver, is the double-difference ionospheric delay at the first frequency point, is the double-difference ionospheric delay at the i-th frequency point, is the double-difference tropospheric delay, λ i is the wavelength of the i-th frequency point of the GNSS signal, a double-difference integer ambiguity of the carrier phase observation of the i-th frequency point, a double-difference carrier phase observation noise of the i-th frequency point.

[0162] Substituting the above formula (10) and formula (11) into the above formula (13), an expression of the double-difference carrier phase observation value is obtained, so that the expression of the double-difference carrier phase observation value includes at least a double-difference geometric distance from the satellite to the receiver a double-difference ionospheric delay, a double-difference integer ambiguity and a double-difference zenith tropospheric wet delay The double-difference carrier phase observation value

[0163]

[0164] wherein, is a double-difference carrier phase observation value of the i-th frequency point, is a double-difference geometric distance from the satellite to the receiver, is a double-difference ionospheric delay of the first frequency point, is a double-difference ionospheric delay of the i-th frequency point, is a double-difference tropospheric dry delay, is a double-difference tropospheric projection function, is a double-difference zenith tropospheric wet delay, λ i is a wavelength of the i-th frequency point of the GNSS signal, is a double-difference integer ambiguity of the carrier phase observation of the i-th frequency point, a double-difference carrier phase observation noise of the i-th frequency point.

[0165] S303, according to the expression of the double-difference pseudo-range observation value and the expression of the double-difference carrier phase observation value, a double-difference non-combined observation model is obtained.

[0166] Optionally, by performing a first double-difference operation on each pseudo-range observation value P i of each satellite in the GNSS observation value at each frequency point and performing a second double-difference operation on each carrier phase observation value φ i , the errors such as satellite clock error, receiver clock error and hardware delay are eliminated, and the error influence of ionospheric delay and tropospheric delay is weakened, according to the expression of the double-difference pseudo-range observation value indicated by the above formula (12) and the expression of the double-difference carrier phase observation value indicated by the above formula (14), a double-difference non-combined observation model indicated by the following formula (3) is constructed:

[0167]

[0168] wherein, is a double-difference pseudo-range observation value of the i-th frequency point, is a double-difference geometric distance from the satellite to the receiver, is a double-difference ionospheric delay of the first frequency point, is a double-difference ionospheric delay of the i-th frequency point, is a double-difference tropospheric dry delay, is a double-difference tropospheric projection function, is a double-difference zenith tropospheric wet delay, is a double-difference pseudo-range observation noise of the i-th frequency point, is a double-difference carrier phase observation value of the i-th frequency point, λ i is a wavelength of the i-th frequency point of the GNSS signal, is a double-difference integer ambiguity of the carrier phase observation value of the i-th frequency point, is a double-difference carrier phase observation noise of the i-th frequency point.

[0169] In the embodiment, by performing the first double-difference operation and the second double-difference operation on each pseudo-range observation value and each carrier phase observation value in the global navigation satellite system observation value, the expression of the double-difference pseudo-range observation value and the expression of the double-difference carrier phase observation value are obtained, and the expression of the double-difference pseudo-range observation value includes the double-difference ionospheric delay and the double-difference zenith tropospheric wet delay, and the expression of the double-difference carrier phase observation value includes the double-difference ionospheric delay, the double-difference integer ambiguity and the double-difference zenith tropospheric wet delay. The errors such as satellite clock error, receiver clock error and hardware delay are eliminated, and the error influence of the ionospheric delay and the tropospheric delay is weakened. Based on the expression of the double-difference pseudo-range observation value and the expression of the double-difference carrier phase observation value, the double-difference non-combination observation model is accurately constructed.

[0170] In the following, the process of constructing the double-difference ionosphere-free combination observation model according to the double-difference non-combination observation model is described in detail.

[0171] Figure 4 The flowchart of constructing the double-difference ionosphere-free combination observation model in the network real-time differential positioning method provided by the embodiment of the application is shown in FIG. 2. Figure 4 The step of constructing the double-difference ionosphere-free combination observation model according to the double-difference non-combination observation model in the step S202 includes the following steps.

[0172] S401, determining the double-difference pseudo-range observation value of the first frequency point and the double-difference pseudo-range observation value of the second frequency point according to the expression of the double-difference pseudo-range observation value.

[0173] Optionally, according to the expression of the double-difference pseudo-range observation value in the above formula (12), i is respectively assigned to 1 and 2 and substituted into the above formula (12) double-difference pseudo-range observation value . the double-difference pseudo-range observation value of the first frequency point and the double-difference pseudo-range observation value of the second frequency point

[0174] S402, determining an expression of the double-difference ionosphere-free combined pseudo-range observation value according to the double-difference pseudo-range observation value of the first frequency point, the double-difference pseudo-range observation value of the second frequency point, and a preset combination coefficient.

[0175] Optionally, the double-difference pseudo-range observation value of the first frequency point the double-difference pseudo-range observation value of the second frequency point and the first coefficient and the second coefficient in the preset combination coefficient are used to determine an initial expression of the double-difference ionosphere-free combined pseudo-range observation value based on the following formula (15):

[0176]

[0177] wherein, is the double-difference ionosphere-free combined pseudo-range observation value, is the first coefficient in the preset combination coefficient, is the second coefficient in the preset combination coefficient, is the square of the frequency corresponding to the first frequency point, is the square of the frequency corresponding to the second frequency point, is the double-difference pseudo-range observation value of the first frequency point, is the double-difference pseudo-range observation value of the second frequency point.

[0178] The above formula (12) is substituted into the above formula (15) to obtain an expression of the double-difference ionosphere-free combined pseudo-range observation value which eliminates the influence of the first-order ionospheric delay error, so that the expression of the double-difference ionosphere-free combined pseudo-range observation value at least includes the double-difference geometric distance from the satellite to the receiver and the double-difference zenith tropospheric wet delay The double-difference ionosphere-free combined pseudo-range observation value

[0179]

[0180] wherein, is the double-difference ionosphere-free combined pseudo-range observation value, is the double-difference geometric distance from the satellite to the receiver, is the double-difference tropospheric dry delay, is the double-difference tropospheric projection function, the double-difference zenith tropospheric wet delay, the double-difference ionosphere-free combined pseudorange observation noise.

[0181] S403, determining the double-difference carrier phase observation value of the first frequency and the double-difference carrier phase observation value of the second frequency according to the expression of the double-difference carrier phase observation value.

[0182] Optionally, according to the expression of the double-difference carrier phase observation value in the above formula (14), i is respectively assigned to 1 and 2 and substituted into the expression of the double-difference carrier phase observation value in the above formula (14), the double-difference carrier phase observation value of the first frequency and the double-difference carrier phase observation value of the second frequency are determined.

[0183] S404, determining the expression of the double-difference ionosphere-free combined carrier phase observation value according to the double-difference carrier phase observation value of the first frequency, the double-difference carrier phase observation value of the second frequency and the preset combination coefficient.

[0184] Optionally, according to the double-difference carrier phase observation value of the first frequency the double-difference carrier phase observation value of the second frequency and the first coefficient and the second coefficient of the preset combination coefficient, the initial expression of the double-difference ionosphere-free combined carrier phase observation value is determined based on the following formula (17):

[0185]

[0186] wherein, is the double-difference ionosphere-free combined carrier phase observation value, is the first coefficient of the preset combination coefficient, is the second coefficient of the preset combination coefficient, is the square of the frequency corresponding to the first frequency, is the square of the frequency corresponding to the second frequency, is the double-difference carrier phase observation value of the first frequency, is the double-difference carrier phase observation value of the second frequency.

[0187] Substituting the above formula (14) into the above formula (17), the expression of the double-difference ionosphere-free combined carrier phase observation value is obtained, which eliminates the influence of the first-order ionospheric delay error, so that the expression of the double-difference ionosphere-free combined carrier phase observation value at least includes the double-difference geometric distance from the satellite to the receiver ​​​double-difference integer ambiguity of the carrier phase observation of the first frequency point double-difference integer ambiguity of the carrier phase observation of the second frequency point and double-difference zenith tropospheric wet delay The double-difference ionosphere-free combined carrier phase observation is represented based on the following formula (18)

[0188]

[0189] wherein, is the double-difference ionosphere-free combined carrier phase observation, is the double-difference geometric distance from the satellite to the receiver, is the double-difference tropospheric dry delay, is the double-difference tropospheric mapping function, is the double-difference zenith tropospheric wet delay, and λ1 and λ2 are the wavelengths of the first frequency point and the second frequency point of the GNSS signal respectively, is the first coefficient in the preset combination coefficient, is the second coefficient in the preset combination coefficient, is the square of the frequency corresponding to the first frequency point, is the square of the frequency corresponding to the second frequency point, and are double-difference integer ambiguities of the carrier phase observation of the first frequency point and the second frequency point respectively, is the double-difference ionosphere-free combined carrier phase observation noise.

[0190] S405, according to the expression of the double-difference ionosphere-free combined pseudorange observation and the expression of the double-difference ionosphere-free combined carrier phase observation, a double-difference ionosphere-free combined observation model is obtained.

[0191] Optionally, according to the characteristic that the ionospheric delay is inversely proportional to the square of the frequency, the influence of the first-order ionospheric delay error is eliminated by linear combination of the preset combination coefficient, and the magnitude of the high-order ionospheric delay error is small, and the high-order ionospheric delay error has been eliminated in the previous double-difference operation process. According to the expression of the double-difference ionosphere-free combined pseudorange observation and the expression of the double-difference ionosphere-free combined carrier phase observation , the double-difference ionosphere-free combined observation model shown in the following formula (6) is constructed:

[0192]

[0193] wherein, is the double-difference ionosphere-free combined pseudorange observation, a double-difference geometric distance from a satellite to a receiver, a double-difference tropospheric dry delay, a double-difference tropospheric mapping function, a double-difference zenith tropospheric wet delay, a double-difference ionosphere-free combined pseudorange observation noise, a double-difference ionosphere-free combined carrier phase observation, λ1 and λ2 are respectively the wavelengths of GNSS signals of a first frequency and a second frequency, a first coefficient in preset combination coefficients, a second coefficient in preset combination coefficients, a square of a frequency corresponding to the first frequency, a square of a frequency corresponding to the second frequency, and a double-difference integer ambiguity of double-difference carrier phase observations of the first frequency and the second frequency, a double-difference ionosphere-free combined carrier phase observation noise.

[0194] In this embodiment, the double-difference pseudorange observations of the first frequency and the second frequency are determined according to the expression of the double-difference pseudorange observation, and the expression of the double-difference ionosphere-free combined pseudorange observation is determined according to the double-difference pseudorange observations of the first frequency and the second frequency, the preset combination coefficients and the expression of the double-difference pseudorange observation. The double-difference carrier phase observations of the first frequency and the second frequency are determined according to the expression of the double-difference carrier phase observation, and the expression of the double-difference ionosphere-free combined carrier phase observation is determined according to the double-difference carrier phase observations of the first frequency and the second frequency, the preset combination coefficients and the expression of the double-difference carrier phase observation. The double-difference ionosphere-free combined observation model is constructed according to the expression of the double-difference ionosphere-free combined pseudorange observation and the expression of the double-difference ionosphere-free combined carrier phase observation. The first-order ionospheric delay error is eliminated in the double-difference ionosphere-free combined observation model.

[0195] In the following, the process of determining the double-difference tropospheric delay, the double-difference integer ambiguity corresponding to each frequency of each satellite and the double-difference ionospheric delay of each satellite at the first frequency is described in detail.

[0196] Figure 5 The flowchart of determining the double-difference tropospheric delay, the double-difference integer ambiguity and the double-difference ionospheric delay in the network real-time differential positioning method provided by the embodiments of the present application is shown in FIG. 1. Figure 5 The steps of determining the double-difference tropospheric delay, the double-difference integer ambiguity corresponding to each frequency of each satellite and the double-difference ionospheric delay of each satellite at the first frequency in step S103 include:

[0197] S501, determining the double-difference zenith tropospheric wet delay according to the initial observation equation, and determining the double-difference tropospheric delay according to the double-difference zenith tropospheric wet delay.

[0198] Optionally, the initial observation equation is solved to obtain the double-difference zenith tropospheric wet delay according to the first weight and the second weight in the initial observation equation and the double-difference zenith tropospheric wet delay The double-difference tropospheric delay is calculated based on the above formula (10) and formula (11)

[0199] S502, Kalman filtering is performed according to the initial observation equation, and the double-difference integer ambiguity corresponding to each frequency of each satellite is determined by using the least-square ambiguity decorrelation adjustment method.

[0200] Optionally, the baseline solution of Kalman filtering is performed on the initial observation equation according to the first weight and the second weight in the initial observation equation, and the double-difference integer ambiguity of the carrier phase observation value corresponding to each frequency of each satellite is obtained by fixing the integer ambiguity through the least-square ambiguity decorrelation adjustment method (Lambda) and

[0201] S503, determining the double-difference integer ambiguity and the carrier phase observation value corresponding to the first frequency of each satellite, and the double-difference integer ambiguity and the carrier phase observation value corresponding to the second frequency of each satellite.

[0202] Optionally, i and j are respectively assigned as 1 and 2 to obtain the double-difference integer ambiguity corresponding to the first frequency of each satellite and the double-difference integer ambiguity corresponding to the second frequency of each satellite and the carrier phase observation value corresponding to the first frequency of each satellite is obtained by solving the initial observation equation and the carrier phase observation value corresponding to the second frequency of each satellite

[0203] S504, determining the double-difference ionospheric delay of each satellite at the first frequency according to the double-difference integer ambiguity and the carrier phase observation value corresponding to the first frequency of each satellite, and the double-difference integer ambiguity and the carrier phase observation value corresponding to the second frequency of each satellite.

[0204] Optionally, the double-difference ionospheric delay of each satellite at the first frequency is determined according to the double-difference integer ambiguity corresponding to the first frequency of each satellite the double-difference integer ambiguity corresponding to the second frequency of each satellite the carrier phase observation value corresponding to the first frequency of each satellite carrier phase observations corresponding to the first frequency of each satellite wavelength λ1 of the first frequency of the GNSS signal, wavelength λ2 of the second frequency of the GNSS signal, and the second coefficient in the preset combination coefficient The double-difference ionospheric delay of each satellite at the first frequency is extracted by using a Geometry-Free (GF for short) combination based on the following formula (19)

[0205]

[0206] wherein, is the double-difference ionospheric delay of each satellite at the first frequency, λ1 and λ2 are respectively the wavelength of the first frequency and the second frequency of the GNSS signal, and are respectively the carrier phase observations corresponding to the first frequency and the second frequency of each satellite, and are respectively the double-difference integer ambiguities corresponding to the first frequency and the second frequency of each satellite, is the second coefficient in the preset combination coefficient, is the square of the frequency corresponding to the first frequency, is the square of the frequency corresponding to the second frequency.

[0207] In this embodiment, the double-difference zenith tropospheric wet delay is obtained by solving the initial observation equation according to the first weight and the second weight in the initial observation equation, and the double-difference tropospheric delay is obtained based on the double-difference zenith tropospheric wet delay. The baseline solution of the Kalman filter is performed on the initial observation equation according to the first weight and the second weight in the initial observation equation, and the integer ambiguity is fixed by the least square ambiguity decorrelation adjustment method to obtain the double-difference integer ambiguity of the carrier phase observations corresponding to each frequency of each satellite. The double-difference integer ambiguity and the carrier phase observation corresponding to the first frequency of each satellite and the double-difference integer ambiguity and the carrier phase observation corresponding to the second frequency of each satellite are determined, and the double-difference ionospheric delay of each satellite at the first frequency is extracted by using the Geometry-Free combination according to the double-difference integer ambiguity and the carrier phase observation corresponding to the first frequency of each satellite and the double-difference integer ambiguity and the carrier phase observation corresponding to the second frequency of each satellite. Based on the double-difference integer ambiguity obtained by accurate solution, the double-difference ionospheric delay of each satellite at the first frequency is accurately extracted, and the influence of the ionospheric delay error is suppressed.

[0208] Hereinafter, the process of determining the double-difference tropospheric delay according to the double-difference zenith tropospheric wet delay is described in detail.

[0209] Figure 6 The flowchart of determining the double-difference tropospheric delay of the network real-time differential positioning method provided by the embodiments of the present application is shown in FIG.Figure 6 As shown in the above step S501, the step of determining the double-difference tropospheric delay according to the double-difference zenith tropospheric wet delay comprises:

[0210] S601, determining the double-difference tropospheric projection function according to the preset tropospheric delay mapping model, and determining the double-difference tropospheric wet delay according to the double-difference tropospheric projection function and the double-difference zenith tropospheric wet delay.

[0211] Optionally, the global mapping function model (GMF), i.e., the tropospheric delay mapping model, is preset in the computer device of the data processing center, and the double-difference tropospheric projection function is calculated based on the preset tropospheric delay mapping model. According to the double-difference tropospheric projection function and the double-difference zenith tropospheric wet delay based on the formula (11), the product of the double-difference tropospheric projection function and the double-difference zenith tropospheric wet delay is taken as the double-difference tropospheric wet delay

[0212]

[0213] wherein, is the double-difference tropospheric wet delay, is the double-difference tropospheric projection function, and is the double-difference zenith tropospheric wet delay.

[0214] S602, determining the double-difference tropospheric dry delay according to the tropospheric delay mapping model, and taking the sum of the double-difference tropospheric dry delay and the double-difference tropospheric wet delay as the double-difference tropospheric delay.

[0215] Optionally, the double-difference tropospheric dry delay is calculated based on the preset tropospheric delay mapping model. According to the formula (10), the sum of the double-difference tropospheric dry delay and the double-difference tropospheric wet delay is taken as the double-difference tropospheric delay

[0216]

[0217] wherein, is the double-difference tropospheric delay, is the double-difference tropospheric dry delay, and is the double-difference tropospheric wet delay.

[0218] In the embodiment, the projection function of the double-difference troposphere is determined according to the preset troposphere delay mapping, the product of the projection function of the double-difference troposphere and the double-difference zenith troposphere wet delay is taken as the double-difference troposphere wet delay, the double-difference troposphere dry delay is determined according to the troposphere delay mapping model, and the sum of the double-difference troposphere dry delay and the double-difference troposphere wet delay is taken as the double-difference troposphere delay. The accuracy of the troposphere delay is improved.

[0219] The following will be described in detail the process of updating the second weight according to the double-difference ionosphere delay of each satellite at the first frequency.

[0220] Figure 7 The flowchart of the network real-time differential positioning method provided by the embodiment of the application is shown in FIG. 1. Figure 7 The step of updating the second weight according to the double-difference ionosphere delay of each satellite at the first frequency in step S103 includes the following steps.

[0221] S701, determining the ionosphere active index of the current epoch according to the double-difference ionosphere delay of each satellite at the first frequency; the ionosphere active index includes the ionosphere active satellite proportion, the ionosphere delay rate of change, and the ionosphere delay mean error.

[0222] Optionally, the double-difference ionosphere delay of each satellite at the first frequency is used to calculate the ionosphere active satellite proportion ratio, the ionosphere delay rate of change rate, and the ionosphere delay mean error std of the current epoch, that is, to determine the ionosphere active index of the current epoch. The ionosphere active satellite is a satellite whose absolute value of the double-difference ionosphere delay at the first frequency is greater than a preset active threshold, that is, if the absolute value of the double-difference ionosphere delay of the satellite at the first frequency is greater than the preset active threshold, the satellite is determined to be an ionosphere active satellite, the number of ionosphere active satellites is counted, and the quotient of the number of ionosphere active satellites and the number of all satellites is taken as the ionosphere active satellite proportion ratio.

[0223] The double-difference ionosphere delay of each satellite at the first frequency is used to calculate the ionosphere delay mean value, and the ionosphere delay mean value is used for variance calculation to obtain the variance of the double-difference ionosphere delay of each satellite at the first frequency and the ionosphere delay mean value. The mean value is calculated to determine the ionosphere delay mean value, the ionosphere delay mean value is used for variance calculation to obtain the variance of the double-difference ionosphere delay of each satellite at the first frequency and the ionosphere delay mean value. The mean error is the square root of the variance, and the square root of the variance is taken to obtain the ionosphere delay mean error std.

[0224] S702, determining and updating the second weight of the next epoch of the current epoch according to the ionosphere active index.

[0225] Optionally, the second weight of the next epoch of the current epoch is determined according to the correspondence of the ionospheric activity index and the positive correlation of the second weight, and the second weight is updated at the next epoch of the current epoch. Wherein, if the ionospheric activity index is high, the second weight is increased at the next epoch of the current epoch, and vice versa, if the ionospheric activity index is low, the second weight is decreased at the next epoch of the current epoch.

[0226] By updating the second weight of the double-difference ionosphere-free combined observation equation, the second observation noise variance R kIF is adjusted to the second observation noise variance of the double-difference ionosphere-free combined observation equation in the target observation equation That is, the second observation noise variance is updated based on the following formula (20):

[0227]

[0228] Wherein, R kIF is the second observation noise variance of the double-difference ionosphere-free combined observation equation in the initial observation equation, w is the second weight of the next epoch of the current epoch, is the second observation noise variance of the double-difference ionosphere-free combined observation equation in the target observation equation.

[0229] The second observation noise variance R kIF is negatively correlated with the second weight, if the ionospheric activity index is high, the second observation noise variance of the double-difference ionosphere-free combined observation equation in the target observation equation can be reduced by increasing the second weight suppress the influence of ionospheric delay error when the ionosphere is active. If the ionospheric activity index is low, the second observation noise variance of the double-difference ionosphere-free combined observation equation in the target observation equation can be increased by decreasing the second weight Avoiding the negative effects caused by amplifying observation noise and multipath error due to excessive dependence on double-difference ionosphere-free combined observation equation.

[0230] In this embodiment, according to the double-difference ionospheric delay of each satellite at the first frequency point, the ionospheric active satellite proportion, the ionospheric delay rate of change and the ionospheric delay mean error of the current epoch are calculated, and the ionospheric activity index of the current epoch is determined. The ionospheric activity index has a positive correlation with the second weight, and the second weight of the next epoch of the current epoch is determined and updated according to the corresponding relationship. If the ionospheric activity index is too high, the second weight is increased in the next epoch of the current epoch to reduce the second observation noise variance of the double-difference ionosphere-free combination observation equation in the target observation equation, and the influence of the ionospheric delay error when the ionosphere is active is suppressed. If the ionospheric activity index is too low, the second weight is reduced in the next epoch of the current epoch to increase the second observation noise variance of the double-difference ionosphere-free combination observation equation in the target observation equation, so as to avoid amplifying the observation noise and multipath error.

[0231] Next, the process of determining and updating the second weight of the next epoch of the current epoch according to the ionospheric activity index is described in detail.

[0232] Figure 8 Another flowchart of the network real-time differential positioning method provided by the embodiment of the present application is shown in FIG. 8. Figure 8 As shown in FIG. 8, the step of determining and updating the second weight of the next epoch of the current epoch according to the ionospheric activity index in step S702 includes:

[0233] S801, determining the first quotient of the ionospheric active satellite proportion and the preset ionospheric active satellite proportion threshold, the second quotient of the ionospheric delay rate of change and the preset ionospheric delay rate of change threshold, and the third quotient of the ionospheric delay mean error and the preset ionospheric delay mean error threshold.

[0234] Optionally, the first quotient of the ionospheric active satellite proportion ratio and the preset ionospheric active satellite proportion threshold ratioThres the second quotient of the ionospheric delay rate rate and the preset ionospheric delay rate threshold rateThres and the third quotient of the ionospheric delay mean error std and the preset ionospheric delay mean error threshold stdThres

[0235] S802, multiplying the first quotient, the second quotient and the third quotient as the second weight of the next epoch of the current epoch, and updating the second weight of the current epoch in the next epoch of the current epoch.

[0236] Optionally, the first quotient of the ionospheric active satellite proportion ratio and the preset ionospheric active satellite proportion threshold ratioThres a second quotient of the ionospheric active satellite proportion ratio and a preset ionospheric active satellite proportion threshold ratioThres a third quotient of the ionospheric delay standard deviation std and a preset ionospheric delay standard deviation threshold stdThres a product of the first quotient, the second quotient and the third quotient as the second weight w of the next epoch of the current epoch, and updating the second weight of the current epoch as the second weight w of the next epoch of the current epoch in the next epoch of the current epoch. The second weight w of the next epoch of the current epoch is determined based on the formula (21):

[0237]

[0238] wherein w is the second weight of the next epoch of the current epoch, ratio is the ionospheric active satellite proportion, ratioThres is the preset ionospheric active satellite proportion threshold, rate is the ionospheric delay rate of change, rateThres is the preset ionospheric delay rate of change threshold, std is the ionospheric delay standard deviation, and stdThres is the preset ionospheric delay standard deviation threshold.

[0239] In the embodiment, the first quotient of the ionospheric active satellite proportion and the preset ionospheric active satellite proportion threshold, the second quotient of the ionospheric delay rate of change and the preset ionospheric delay rate of change threshold, and the third quotient of the ionospheric delay standard deviation and the preset ionospheric delay standard deviation threshold are calculated, and a product of the first quotient, the second quotient and the third quotient is taken as the second weight of the next epoch of the current epoch, and the second weight of the current epoch is updated in the next epoch of the current epoch. By presetting the ionospheric active satellite proportion threshold, the ionospheric delay rate of change threshold and the ionospheric delay standard deviation threshold respectively, the accuracy of determining the ionospheric activity degree is improved, and the misjudgment probability is reduced.

[0240] Figure 9 Another flowchart for updating the second weight of the network real-time differential positioning method provided by the embodiment of the application is shown in FIG. 7B. Figure 9 As shown in FIG. 7B, the step of determining and updating the second weight of the next epoch of the current epoch according to the ionospheric activity index in the step S702 includes:

[0241] S901, if the ionosphere active satellite proportion is greater than the preset ionosphere active satellite proportion threshold, the ionosphere delay rate of change is greater than the preset ionosphere delay rate of change threshold, and the ionosphere delay mean error is greater than the preset ionosphere delay mean error threshold, it is determined that the ionosphere is in an active period, and the first difference between the ionosphere active satellite proportion and the preset ionosphere active satellite proportion threshold, the second difference between the ionosphere delay rate of change and the preset ionosphere delay rate of change threshold, and the third difference between the ionosphere delay mean error and the preset ionosphere delay mean error threshold are determined and updated. The second weight of the next epoch of the current epoch is determined and updated according to the first difference, the second difference and the third difference.

[0242] Optionally, according to the size relationship between the ionosphere active satellite proportion ratio and the preset ionosphere active satellite proportion threshold ratioThres, the size relationship between the ionosphere delay rate of change rate and the preset ionosphere delay rate of change threshold rateThres, and the size relationship between the ionosphere delay mean error std and the preset ionosphere delay mean error threshold stdThres, the active state of the ionosphere is determined. Wherein, if the ionosphere active satellite proportion ratio, the ionosphere delay rate of change rate and the ionosphere delay mean error std of the current epoch are all greater than the corresponding threshold, it is determined that the ionosphere is in an active period.

[0243] Specifically, if the ionosphere active satellite proportion ratio is greater than the preset ionosphere active satellite proportion threshold ratioThres, the ionosphere delay rate of change rate is greater than the preset ionosphere delay rate of change threshold rateThres, and the ionosphere delay mean error std is greater than the preset ionosphere delay mean error threshold stdThres, it is determined that the ionosphere is in an active period.

[0244] The first difference ratio-ratioThres between the ionosphere active satellite proportion ratio and the preset ionosphere active satellite proportion threshold ratioThres, the second difference rate-rateThres between the ionosphere delay rate of change rate and the preset ionosphere delay rate of change threshold rateThres, and the third difference std-stdThres between the ionosphere delay mean error std and the preset ionosphere delay mean error threshold stdThres are calculated, and the second weight w of the next epoch of the current epoch is determined and updated. Wherein, the greater the first difference ratio-ratioThres, the second difference rate-rateThres or the third difference std-stdThres, the greater the second weight w of the next epoch of the current epoch.

[0245] S902, otherwise, it is determined that the ionosphere is in a calm period, and the second weight of the current epoch is taken as the second weight of the next epoch of the current epoch.

[0246] Optionally, if any one of the ionosphere active satellite ratio, ionosphere delay rate of change, or ionosphere delay standard deviation of the current epoch is less than or equal to the corresponding threshold, it is determined that the ionosphere is in a quiet period.

[0247] Specifically, if the ionosphere active satellite ratio is less than or equal to a preset ionosphere active satellite ratio threshold, or the ionosphere delay rate of change is less than or equal to a preset ionosphere delay rate of change threshold, or the ionosphere delay standard deviation is less than or equal to a preset ionosphere delay standard deviation threshold, it is determined that the ionosphere is in a quiet period, and the second weight of the current epoch is directly used as the second weight of the next epoch of the current epoch without updating the second weight.

[0248] In this embodiment, the active state of the ionosphere is determined according to the size relationship between the ionosphere active satellite ratio and the preset ionosphere active satellite ratio threshold, the size relationship between the ionosphere delay rate of change and the preset ionosphere delay rate of change threshold, and the size relationship between the ionosphere delay standard deviation and the preset ionosphere delay standard deviation threshold. If the ionosphere active satellite ratio, the ionosphere delay rate of change, and the ionosphere delay standard deviation of the current epoch are all greater than the corresponding thresholds, it is determined that the ionosphere is in an active period. The first difference between the ionosphere active satellite ratio and the preset ionosphere active satellite ratio threshold, the second difference between the ionosphere delay rate of change and the preset ionosphere delay rate of change threshold, and the third difference between the ionosphere delay standard deviation and the preset ionosphere delay standard deviation threshold are calculated, and the second weight of the next epoch of the current epoch is determined and updated according to the first difference, the second difference, and the third difference. If any one of the ionosphere active satellite ratio, the ionosphere delay rate of change, or the ionosphere delay standard deviation of the current epoch is less than or equal to the corresponding threshold, it is determined that the ionosphere is in a quiet period, and the second weight of the current epoch is directly used as the second weight of the next epoch of the current epoch without updating the second weight. By setting all the indicators in the ionosphere active index to be greater than the corresponding threshold, the weight is only increased when the ionosphere is in an active period, which reduces the probability of misjudgment of the active period and the quiet period and improves the accuracy of updating the second weight.

[0249] Specifically, if the ionosphere active satellite ratio is less than or equal to a preset ionosphere active satellite ratio threshold, or the ionosphere delay rate of change is less than or equal to a preset ionosphere delay rate of change threshold, or the ionosphere delay standard deviation is less than or equal to a preset ionosphere delay standard deviation threshold, it is determined that the ionosphere is in a quiet period, and the second weight of the current epoch is directly used as the second weight of the next epoch of the current epoch without updating the second weight.

[0250] Based on the same inventive concept, the application also provides a network real-time differential positioning device corresponding to the network real-time differential positioning method. Since the device solves problems in the same principle as the network real-time differential positioning method, the implementation of the device can be referred to the implementation of the method, and the repeated parts will not be described here.

[0251] Figure 10 The module structure diagram of the network real-time differential positioning device provided by the application is shown in FIG. 1, which includes: Figure 10

[0252] The acquisition module 1001 is configured to acquire global navigation satellite system observation values of each satellite at each frequency point, wherein the global navigation satellite system observation values include pseudo-range observation values and carrier phase observation values.

[0253] The construction module 1002 is configured to construct an initial observation equation according to the global navigation satellite system observation values, wherein the initial observation equation includes a double-difference non-combination observation equation with a first weight and a double-difference ionosphere-free combination observation equation with a second weight, and the first weight is greater than the second weight.

[0254] The determination module 1003 is configured to determine a double-difference troposphere delay, a double-difference integer ambiguity corresponding to each frequency point of each satellite, and a double-difference ionosphere delay of each satellite at a first frequency point by performing baseline solution according to the initial observation equation, and update the second weight according to the double-difference ionosphere delay of each satellite at the first frequency point to obtain a target observation equation.

[0255] The positioning module 1004 is configured to perform network real-time differential positioning based on the target observation equation.

[0256] As an optional implementation, the construction module 1002 is specifically configured to:

[0257] perform double-difference operation according to the global navigation satellite system observation values to obtain a double-difference non-combination observation model, construct the double-difference non-combination observation equation and a first observation noise variance of the double-difference non-combination observation equation according to the double-difference non-combination observation model, and the first observation noise variance is used to represent the first weight; the double-difference non-combination observation model includes an expression of double-difference pseudo-range observation values and an expression of double-difference carrier phase observation values.

[0258] construct a double-difference ionosphere-free combination observation model according to the double-difference non-combination observation model, construct the double-difference ionosphere-free combination observation equation and a second observation noise variance of the double-difference ionosphere-free combination observation equation according to the double-difference ionosphere-free combination observation model, and the second observation noise variance is used to represent the second weight; the double-difference ionosphere-free combination observation model includes an expression of double-difference ionosphere-free combination pseudo-range observation values and an expression of double-difference ionosphere-free combination carrier phase observation values.​

[0259] The initial observation equation is constructed according to the double-difference non-combined observation equation, the first observation noise variance, the double-difference ionosphere-free combined observation equation, and the second observation noise variance.

[0260] As an optional implementation, the constructing module 1002 is specifically configured to:

[0261] The first double-difference operation is performed on each pseudo-range observation value in the global navigation satellite system observation value, to obtain an expression of a double-difference pseudo-range observation value, the expression of the double-difference pseudo-range observation value at least including a double-difference geometric distance, a double-difference ionosphere delay, and a double-difference zenith troposphere wet delay.

[0262] The second double-difference operation is performed on each carrier phase observation value in the global navigation satellite system observation value, to obtain an expression of a double-difference carrier phase observation value, the expression of the double-difference carrier phase observation value at least including a double-difference geometric distance, a double-difference ionosphere delay, a double-difference integer ambiguity, and a double-difference zenith troposphere wet delay.

[0263] The double-difference non-combined observation model is obtained according to the expression of the double-difference pseudo-range observation value and the expression of the double-difference carrier phase observation value.

[0264] As an optional implementation, the constructing module 1002 is specifically configured to:

[0265] The double-difference pseudo-range observation value of the first frequency point and the double-difference pseudo-range observation value of the second frequency point are determined according to the expression of the double-difference pseudo-range observation value.

[0266] The expression of the double-difference ionosphere-free combined pseudo-range observation value is determined according to the double-difference pseudo-range observation value of the first frequency point, the double-difference pseudo-range observation value of the second frequency point, and a preset combination coefficient.

[0267] The double-difference carrier phase observation value of the first frequency point and the double-difference carrier phase observation value of the second frequency point are determined according to the expression of the double-difference carrier phase observation value.

[0268] The expression of the double-difference ionosphere-free combined carrier phase observation value is determined according to the double-difference carrier phase observation value of the first frequency point, the double-difference carrier phase observation value of the second frequency point, and a preset combination coefficient.

[0269] The double-difference ionosphere-free combined observation model is obtained according to the expression of the double-difference ionosphere-free combined pseudo-range observation value and the expression of the double-difference ionosphere-free combined carrier phase observation value.

[0270] As an optional implementation, the determining module 1003 is specifically configured to:

[0271] According to the initial observation equation, the double-difference zenith tropospheric wet delay is determined, and according to the double-difference zenith tropospheric wet delay, the double-difference tropospheric delay is determined.

[0272] According to the initial observation equation, the double-difference zenith tropospheric wet delay is determined, and according to the double-difference zenith tropospheric wet delay, the double-difference tropospheric delay is determined.

[0273] According to the initial observation equation, the double-difference zenith tropospheric wet delay is determined, and according to the double-difference zenith tropospheric wet delay, the double-difference tropospheric delay is determined.

[0274] According to the initial observation equation, the double-difference zenith tropospheric wet delay is determined, and according to the double-difference zenith tropospheric wet delay, the double-difference tropospheric delay is determined.

[0275] As an optional implementation, the determining module 1003 is specifically configured to:

[0276] According to the initial observation equation, the double-difference zenith tropospheric wet delay is determined, and according to the double-difference zenith tropospheric wet delay, the double-difference tropospheric delay is determined.

[0277] According to the initial observation equation, the double-difference zenith tropospheric wet delay is determined, and according to the double-difference zenith tropospheric wet delay, the double-difference tropospheric delay is determined.

[0278] As an optional implementation, the determining module 1003 is specifically configured to:

[0279] According to the initial observation equation, the double-difference zenith tropospheric wet delay is determined, and according to the double-difference zenith tropospheric wet delay, the double-difference tropospheric delay is determined.

[0280] According to the initial observation equation, the double-difference zenith tropospheric wet delay is determined, and according to the double-difference zenith tropospheric wet delay, the double-difference tropospheric delay is determined.

[0281] As an optional implementation, the determining module 1003 is specifically configured to:

[0282] According to the initial observation equation, the double-difference zenith tropospheric wet delay is determined, and according to the double-difference zenith tropospheric wet delay, the double-difference tropospheric delay is determined.

[0283] According to the initial observation equation, the double-difference zenith tropospheric wet delay is determined, and according to the double-difference zenith tropospheric wet delay, the double-difference tropospheric delay is determined.

[0284] As an optional implementation, the determining module 1003 is specifically used for:

[0285] If the proportion of active ionospheric satellites is greater than a preset threshold for the proportion of active ionospheric satellites, the rate of change of ionospheric delay is greater than a preset threshold for the rate of change of ionospheric delay, and the mean square error of ionospheric delay is greater than a preset threshold for the mean square error of ionospheric delay, then the ionosphere is determined to be in an active period. The first difference between the proportion of active ionospheric satellites and the preset threshold for the proportion of active ionospheric satellites, the second difference between the rate of change of ionospheric delay and the preset threshold for the rate of change of ionospheric delay, and the third difference between the mean square error of ionospheric delay and the preset threshold for the mean square error of ionospheric delay are determined. The second weight of the next epoch of the current epoch is determined and updated based on the first difference, the second difference, and the third difference.

[0286] Otherwise, determine that the ionosphere is in a quiescent period, and use the second weight of the current epoch as the second weight of the next epoch.

[0287] This application also provides a computer device, such as... Figure 11 The diagram shown is a schematic representation of the structure of a computer device provided in an embodiment of this application, including: a processor 111, a memory 112, and a bus 113. The memory 112 stores machine-readable instructions executable by the processor 111 (e.g., ...). Figure 10 The device in the middle obtains the execution instructions corresponding to the module 1001, the construction module 1002, the determination module 1003 and the positioning module 1004, etc. When the computer device is running, the processor 111 and the memory 112 communicate through the bus 113. When the machine-readable instructions are executed by the processor 111, the steps of the network real-time differential positioning method in the above embodiment are executed.

[0288] This application also provides a computer-readable storage medium storing a computer program. When the computer program is run by a processor, it executes the steps of the network real-time differential positioning method described in the above embodiments.

[0289] Those skilled in the art can clearly understand the specific working process of the system and the device described above for the convenience and brevity of description, and the corresponding process in the method embodiment can be referred to, and the present application will not be repeated here. In several embodiments provided in the present application, it should be understood that the disclosed system, device and method can be implemented by other ways. The device embodiments described above are only schematic, for example, the division of the modules is only a logical function division, and the actual implementation can have another division manner, for example, a plurality of modules or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the displayed or discussed each other can be indirect coupling or communication connection through some communication interface, device or module, which can be electrical, mechanical or other forms.

[0290] In addition, each functional unit in each embodiment of the present application can be integrated in one processing unit, or each unit can be physically present separately, or two or more units can be integrated in one unit. When the functions are realized in the form of software functional units and sold or used as independent products, they can be stored in a computer readable storage medium. Based on this understanding, the technical solutions of the present application essentially or say the parts that make contributions to the prior art or parts of the technical solutions can be embodied in the form of software products, which are stored in a storage medium and include a plurality of instructions for making a computer device (which can be a personal computer, a server, or a network device, etc.) execute all or part of the steps of the methods described in each embodiment of the present application. The foregoing storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk or an optical disk, and various program code storage media.

[0291] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical scope disclosed in the present application, which should be covered within the protection scope of the present application.

Claims

1. A network real-time kinematic positioning method, characterized by, The method comprises the following steps: obtaining global navigation satellite system observation values of each satellite at each frequency point, wherein the global navigation satellite system observation values comprise pseudo-range observation values and carrier phase observation values; constructing an initial observation equation according to the global navigation satellite system observation values, wherein the initial observation equation comprises a double-difference non-combination observation equation with a first weight and a double-difference ionosphere-free combination observation equation with a second weight, and the first weight is greater than the second weight; performing baseline solution according to the initial observation equation to determine double-difference tropospheric delay, double-difference whole-cycle ambiguity corresponding to each frequency point of each satellite, and double-difference ionospheric delay of each satellite at a first frequency point, and updating the second weight according to the double-difference ionospheric delay of each satellite at the first frequency point to obtain a target observation equation; performing network real-time differential positioning based on the target observation equation.

2. The method of claim 1, wherein, The step of constructing an initial observation equation according to the global navigation satellite system observation values comprises the following steps: performing double-difference operation according to the global navigation satellite system observation values to obtain a double-difference non-combination observation model, and constructing the double-difference non-combination observation equation and a first observation noise variance of the double-difference non-combination observation equation according to the double-difference non-combination observation model, wherein the first observation noise variance is used to represent the first weight; the double-difference non-combination observation model comprises an expression of double-difference pseudo-range observation values and an expression of double-difference carrier phase observation values; constructing a double-difference ionosphere-free combination observation model according to the double-difference non-combination observation model, and constructing the double-difference ionosphere-free combination observation equation and a second observation noise variance of the double-difference ionosphere-free combination observation equation according to the double-difference ionosphere-free combination observation model, wherein the second observation noise variance is used to represent the second weight; the double-difference ionosphere-free combination observation model comprises an expression of double-difference ionosphere-free combination pseudo-range observation values and an expression of double-difference ionosphere-free combination carrier phase observation values; constructing the initial observation equation according to the double-difference non-combination observation equation, the first observation noise variance, the double-difference ionosphere-free combination observation equation and the second observation noise variance.

3. The method of claim 2, wherein, The step of performing double-difference operation according to the global navigation satellite system observation values to obtain a double-difference non-combination observation model comprises the following steps: performing first double-difference operation on each pseudo-range observation value in the global navigation satellite system observation values to obtain the expression of the double-difference pseudo-range observation values, wherein the expression of the double-difference pseudo-range observation values at least comprises double-difference geometric distance, double-difference ionospheric delay and double-difference zenith tropospheric wet delay; performing second double-difference operation on each carrier phase observation value in the global navigation satellite system observation values to obtain the expression of the double-difference carrier phase observation values, wherein the expression of the double-difference carrier phase observation values at least comprises the double-difference geometric distance, the double-difference ionospheric delay, the double-difference whole-cycle ambiguity and the double-difference zenith tropospheric wet delay; obtaining the double-difference non-combination observation model according to the expression of the double-difference pseudo-range observation values and the expression of the double-difference carrier phase observation values.

4. The method of claim 2, wherein, The method comprises the following steps: According to the expression of the double-difference pseudorange observation value, the double-difference pseudorange observation value of the first frequency point and the double-difference pseudorange observation value of the second frequency point are determined; According to the expression of the double-difference pseudorange observation value, the double-difference pseudorange observation value of the first frequency point and the double-difference pseudorange observation value of the second frequency point are determined; According to the double-difference pseudorange observation value of the first frequency point, the double-difference pseudorange observation value of the second frequency point and the preset combination coefficient, the expression of the double-difference ionosphere-free combined pseudorange observation value is determined; According to the expression of the double-difference carrier phase observation value, the double-difference carrier phase observation value of the first frequency point and the double-difference carrier phase observation value of the second frequency point are determined; According to the expression of the double-difference carrier phase observation value, the double-difference carrier phase observation value of the first frequency point and the double-difference carrier phase observation value of the second frequency point are determined; 5. The method of claim 3, wherein, According to the expression of the double-difference ionosphere-free combined pseudorange observation value and the expression of the double-difference ionosphere-free combined carrier phase observation value, the double-difference ionosphere-free combined observation model is obtained. The method comprises the following steps: According to the initial observation equation, the double-difference zenith tropospheric wet delay is determined, and according to the double-difference zenith tropospheric wet delay, the double-difference tropospheric delay is determined; According to the initial observation equation, Kalman filtering is performed, and the double-difference integer ambiguity corresponding to each frequency point of each satellite is determined by using a least square ambiguity decorrelation adjustment method; The double-difference integer ambiguity and the carrier phase observation value corresponding to the first frequency point of each satellite and the double-difference integer ambiguity and the carrier phase observation value corresponding to the second frequency point of each satellite are determined; 6. The method of claim 5, wherein, According to the double-difference integer ambiguity and the carrier phase observation value corresponding to the first frequency point of each satellite and the double-difference integer ambiguity and the carrier phase observation value corresponding to the second frequency point of each satellite, the double-difference ionospheric delay of each satellite at the first frequency point is determined. The method comprises the following steps: According to the double-difference zenith tropospheric wet delay, the double-difference tropospheric delay is determined, which comprises the following steps:

7. The method of claim 1, wherein, According to a preset tropospheric delay mapping model, a double-difference tropospheric projection function is determined, and according to the double-difference tropospheric projection function and the double-difference zenith tropospheric wet delay, the double-difference tropospheric wet delay is determined; According to the tropospheric delay mapping model, the double-difference tropospheric dry delay is determined, and the sum of the double-difference tropospheric dry delay and the double-difference tropospheric wet delay is taken as the double-difference tropospheric delay. The method comprises the following steps:

8. The method of claim 7, wherein, According to the double-difference ionospheric delay of each satellite at the first frequency point, the ionospheric activity index of the current epoch is determined; the ionospheric activity index comprises an ionospheric active satellite proportion, an ionospheric delay change rate and an ionospheric delay mean error; According to the ionospheric activity index, the second weight of the next epoch of the current epoch is determined and updated. The method comprises the following steps: determine a first quotient of the ionosphere active satellite proportion and a preset ionosphere active satellite proportion threshold, a second quotient of the ionosphere delay rate of change and a preset ionosphere delay rate of change threshold, and a third quotient of the ionosphere delay mean error and a preset ionosphere delay mean error threshold; multiply the first quotient, the second quotient, and the third quotient to obtain a second weight of a next epoch of a current epoch, and update the second weight of the next epoch of the current epoch.

9. The method of claim 7, wherein, The method further comprises: if the ionosphere active satellite proportion is greater than the preset ionosphere active satellite proportion threshold, the ionosphere delay rate of change is greater than the preset ionosphere delay rate of change threshold, and the ionosphere delay mean error is greater than the preset ionosphere delay mean error threshold, it is determined that the ionosphere is in an active period, and a first difference between the ionosphere active satellite proportion and the preset ionosphere active satellite proportion threshold, a second difference between the ionosphere delay rate of change and the preset ionosphere delay rate of change threshold, and a third difference between the ionosphere delay mean error and the preset ionosphere delay mean error threshold are determined, and a second weight of a next epoch of a current epoch is determined and updated according to the first difference, the second difference, and the third difference; otherwise, it is determined that the ionosphere is in a calm period, and a second weight of a current epoch is taken as a second weight of a next epoch of the current epoch.

10. A computer device, comprising: The method further comprises: a processor, a memory, and a bus, the memory storing machine readable instructions executable by the processor, when the computer device is running, the processor and the memory communicate through the bus, the processor executes the machine readable instructions, and the steps of the network real-time difference positioning method according to any one of claims 1 to 9 are executed.

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