Network real-time differential positioning method and computer equipment

Abstract

The invention provides a network real-time differential positioning method and computer equipment, and the method comprises the steps: obtaining a global navigation satellite system observation value of each satellite at each frequency point, the global navigation satellite system observation value comprising a pseudo-range observation value and a carrier phase observation value; according to the global navigation satellite system observation value, an initial observation equation is constructed, 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 larger than the second weight; performing baseline solution according to the initial observation equation, determining double-difference troposphere delay, double-difference integer ambiguity corresponding to each frequency point of each satellite and double-difference ionosphere delay of each satellite at the first frequency point, and updating a second weight according to the double-difference ionosphere delay of each satellite at the first frequency point to obtain a target observation equation; and network real-time differential positioning is carried out based on the target observation equation so as to improve the accuracy of baseline solution and the positioning precision.

Description

Technical Field

[0001] The present application relates to the field of positioning technology, and in particular to a network real-time differential positioning method and computer equipment. Background Art

[0002] The Network Real-time Kinematic (NRTK) technology obtains a baseline list based on the real-time observation data of the base station, and uses the baseline to solve the fixed integer ambiguity, extracts the atmospheric delay including the ionospheric delay and the tropospheric delay, and performs atmospheric modeling based on the atmospheric delay and generates the Virtual Reference Station (VRS) data, and achieves high-precision positioning based on the VRS data. Among them, 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 double-difference non-combined observation equation is usually used for baseline solution. In general scenarios, the baseline solution scheme can obtain accurate whole-cycle ambiguity, thereby obtaining accurate atmospheric delay, but the baseline solution scheme cannot be applied to all regions. For example, the solar radiation intensity in low-latitude areas close to the equator is higher, and the electron density of the ionosphere varies more than other areas, which has a greater impact on the propagation of the Global Navigation Satellite System (GNSS) signal. In addition, the vertical structure of the ionosphere in low-latitude areas is different from that in mid- and high-latitude areas, which will reduce the applicability of the ionosphere model and thus affect the positioning accuracy. In addition, areas with changeable climates are easily affected by climates such as monsoons or tropical storms, resulting in poor stability of the ionosphere. When performing baseline solution in the above-mentioned areas, it is easy to be affected by the more active ionosphere, resulting in ambiguity fixation errors, which in turn leads to large errors in the extraction of atmospheric delays, reducing the accuracy of VRS data and affecting the positioning accuracy of network RTK in some areas.

[0004] Therefore, there are certain limitations in the prior art of using double-difference non-combined observation equations to perform baseline solution. Summary of the invention

[0005] The purpose of this application is to provide a network real-time differential positioning method and computer equipment to address the deficiencies in the above-mentioned prior art, so as to solve the practical problem of low positioning accuracy of network RTK in some areas in the prior art.

[0006] To achieve the above purpose, the technical solution adopted in the embodiment of the present application is as follows:

[0007] In a first aspect, an embodiment of the present application provides 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, wherein the global navigation satellite system observation values ​​include pseudorange observation values ​​and carrier phase observation values;

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

[0010] Performing a baseline solution according to the initial observation equation, determining 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 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] Network real-time differential positioning is performed based on the target observation equation.

[0012] As an optional implementation, constructing the initial observation equation according to the observation values ​​of each global navigation satellite system includes:

[0013] According to the global navigation satellite system observation value, a double difference operation is performed to obtain a double difference non-combined observation model, and according to the double difference non-combined observation model, the double difference non-combined observation equation and the first observation noise variance of the double difference non-combined observation equation are constructed, and the first observation noise variance is used to characterize the first weight; the double difference non-combined observation model includes an expression of a double difference pseudorange observation value and an expression of a double difference carrier phase observation value;

[0014] According to the double-difference non-combined observation model, the double-difference ionosphere-free combined observation model is constructed; according to the double-difference ionosphere-free combined observation model, 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, and the second observation noise variance is used to characterize the second weight; the double-difference ionosphere-free combined observation model includes an expression of a double-difference ionosphere-free combined pseudorange observation value and an expression of a double-difference ionosphere-free combined carrier phase observation value;

[0015] The initial observation equation is constructed according to the double-difference non-combined observation equation, the first observation noise variance, the double-difference ionospheric-free combined observation equation and the second observation noise variance.

[0016] As an optional implementation, performing a double difference operation according to each of the global navigation satellite system observation values ​​to obtain a double difference non-combined observation model includes:

[0017] Performing a first double difference operation on each pseudorange observation value in the global navigation satellite system observation value to obtain an expression of the double difference pseudorange observation value, wherein the expression of the double difference pseudorange observation value at least includes a double difference geometric distance, a double difference ionospheric delay, and a double difference zenith tropospheric wet delay;

[0018] Performing a second double difference operation on each carrier phase observation value in the global navigation satellite system observation value to obtain an expression of the double difference carrier phase observation value, wherein 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;

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

[0020] As an optional implementation manner, constructing the double-difference ionospheric-free combined observation model according to the double-difference non-combined observation model includes:

[0021] Determine 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;

[0022] Determine an expression for a double-difference ionospheric-free combined pseudorange observation value 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 a preset combination coefficient;

[0023] Determine 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 according to the expression of the double-difference carrier phase observation value;

[0024] Determine an expression of a double-difference ionospheric-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;

[0025] According to the expression of the double-difference ionospheric-free combined pseudorange observation value and the expression of the double-difference ionospheric-free combined carrier phase observation value, the double-difference ionospheric-free combined observation model is obtained.

[0026] As an optional implementation manner, determining 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 includes:

[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] Kalman filtering is performed according to the initial observation equation, and the double-difference integer ambiguity corresponding to each frequency point of each satellite is determined by using the least squares ambiguity reduction correlation adjustment method;

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

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

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

[0032] 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;

[0033] A double-difference tropospheric dry delay is determined according to the tropospheric delay mapping model, and a sum of the double-difference tropospheric dry delay and the double-difference tropospheric wet delay is used as the double-difference tropospheric delay.

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

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

[0036] According to the ionospheric activity index, a second weight of the next epoch of the current epoch is determined and updated.

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

[0038] Determine a first quotient of the ionospheric active satellite ratio and a preset ionospheric active satellite ratio 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] 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.

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

[0041] If the proportion of active satellites in the ionosphere is greater than a preset threshold value of the proportion of active satellites in the ionosphere, the rate of change of ionosphere delay is greater than a preset threshold value of the rate of change of ionosphere delay, and the error in ionosphere delay is greater than a preset threshold value of the error in ionosphere delay, it is determined that the ionosphere is in an active period, and a first difference between the proportion of active satellites in the ionosphere and the preset threshold value of the proportion of active satellites in the ionosphere, a second difference between the rate of change of ionosphere delay and the preset threshold value of the rate of change of ionosphere delay, and a third difference between the error in ionosphere delay and the preset threshold value of the error in ionosphere delay are determined, and a 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 quiet period, and the second weight of the current epoch is used 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 differential positioning device, the device comprising:

[0044] An acquisition module is used to acquire global navigation satellite system observation values ​​of each satellite at each frequency point, wherein the global navigation satellite system observation values ​​include pseudorange observation values ​​and carrier phase observation values;

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

[0046] A determination module is used to perform a baseline solution according to the initial observation equation, determine 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, and update the second weight according to the double difference ionospheric delay of each satellite at the first frequency point to obtain the target observation equation;

[0047] A positioning module is used to perform network real-time differential positioning based on the target observation equation.

[0048] As an optional implementation, the building module is specifically used for:

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

[0050] According to the double-difference non-combined observation model, the double-difference ionosphere-free combined observation model is constructed; according to the double-difference ionosphere-free combined observation model, 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, and the second observation noise variance is used to characterize the second weight; the double-difference ionosphere-free combined observation model includes an expression of a double-difference ionosphere-free combined pseudorange observation value and an expression of a double-difference ionosphere-free combined carrier phase observation value;

[0051] The initial observation equation is constructed according to the double-difference non-combined observation equation, the first observation noise variance, the double-difference ionospheric-free combined observation equation and the second observation noise variance.

[0052] As an optional implementation, the building module is specifically used for:

[0053] Performing a first double difference operation on each pseudorange observation value in the global navigation satellite system observation value to obtain an expression of the double difference pseudorange observation value, wherein the expression of the double difference pseudorange observation value at least includes a double difference geometric distance, a double difference ionospheric delay, and a double difference zenith tropospheric wet delay;

[0054] Performing a second double difference operation on each carrier phase observation value in the global navigation satellite system observation value to obtain an expression of the double difference carrier phase observation value, wherein 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;

[0055] The double-difference non-combined observation model is obtained according to the expression of the double-difference pseudorange observation value and the expression of the double-difference carrier phase observation value.

[0056] As an optional implementation, the building module is specifically used for:

[0057] Determine 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;

[0058] Determine an expression for a double-difference ionospheric-free combined pseudorange observation value 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 a preset combination coefficient;

[0059] Determine 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 according to the expression of the double-difference carrier phase observation value;

[0060] Determine an expression of a double-difference ionospheric-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] According to the expression of the double-difference ionospheric-free combined pseudorange observation value and the expression of the double-difference ionospheric-free combined carrier phase observation value, the double-difference ionospheric-free combined observation model is obtained.

[0062] As an optional implementation manner, the determining module is specifically used for:

[0063] 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;

[0064] Kalman filtering is performed according to the initial observation equation, and the double-difference integer ambiguity corresponding to each frequency point of each satellite is determined by using the least squares ambiguity reduction correlation adjustment method;

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

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

[0067] As an optional implementation manner, the determining module is specifically used for:

[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] A double-difference tropospheric dry delay is determined according to the tropospheric delay mapping model, and a sum of the double-difference tropospheric dry delay and the double-difference tropospheric wet delay is used as the double-difference tropospheric delay.

[0070] As an optional implementation manner, the determining module is specifically used for:

[0071] Determine an ionospheric activity index of a current epoch according to the double-difference ionospheric delay of each satellite at the first frequency point; the ionospheric activity index includes a proportion of ionospheric active satellites, a rate of change of ionospheric delay, and a mean error of ionospheric delay;

[0072] According to the ionospheric activity index, a second weight of the next epoch of the current epoch is determined and updated.

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

[0074] Determine a first quotient of the ionospheric active satellite ratio and a preset ionospheric active satellite ratio 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;

[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 manner, the determining module is specifically used for:

[0077] If the proportion of active satellites in the ionosphere is greater than a preset threshold value of the proportion of active satellites in the ionosphere, the rate of change of ionosphere delay is greater than a preset threshold value of the rate of change of ionosphere delay, and the error in ionosphere delay is greater than a preset threshold value of the error in ionosphere delay, it is determined that the ionosphere is in an active period, and a first difference between the proportion of active satellites in the ionosphere and the preset threshold value of the proportion of active satellites in the ionosphere, a second difference between the rate of change of ionosphere delay and the preset threshold value of the rate of change of ionosphere delay, and a third difference between the error in ionosphere delay and the preset threshold value of the error in ionosphere delay are determined, and a 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;

[0078] Otherwise, it is determined that the ionosphere is in a quiet period, and the second weight of the current epoch is used as the second weight of the next epoch of the current epoch.

[0079] In a third aspect, an embodiment of the present application provides a computer device, comprising: a processor, a memory and a bus, wherein the memory stores machine-readable instructions executable by the processor, and when the computer device is running, the processor communicates with the memory through 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, an embodiment of the present application provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the network real-time differential positioning method described in the first aspect above are executed.

[0081] The beneficial effects of this application are:

[0082] The present application provides a network real-time differential positioning method and computer equipment, which receive the global navigation satellite system observation values ​​of each satellite at each frequency point sent by each reference station, including pseudorange observation values ​​and carrier phase observation values, and construct an initial observation equation 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 based on the global navigation satellite system observation values ​​of each satellite at each frequency point and the double difference non-combined observation model and the double difference ionosphere-free combined observation model. According to the double difference non-combined observation equation with a larger first weight and the double difference ionosphere-free combined observation equation with a smaller second weight in the initial observation equation, the baseline of the starting epoch is mainly solved by the double difference non-combined observation equation in the initial observation equation to determine the double difference tropospheric delay, the double difference integer ambiguity corresponding to each frequency point of each satellite, and the double difference ionosphere delay of each satellite at the first frequency point. Based on the ionospheric activity of the area to be positioned under the current climate conditions represented by the double difference ionosphere delay of each satellite at the first frequency point, the second weight of the double difference ionosphere-free combined observation equation is updated to obtain the target observation equation. The baseline solution is performed again based on the target observation equation to determine the atmospheric delay, and the atmospheric modeling is performed for the baseline atmospheric delay around the approximate coordinates. The virtual mobile station data is generated and sent to the user terminal to achieve high-precision network real-time differential positioning. By adding a 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 used to form the observation equation and participate in the baseline solution. The weight of the double-difference ionosphere-free combined observation equation in the observation equation is adjusted adaptively in real time according to the activity of the ionosphere, so that the baseline solution is more dependent on the double-difference non-combined observation equation during the ionospheric quiet period with low ionospheric activity, avoiding the noise and multipath errors of the observation values ​​being amplified. During the ionospheric active period with high ionospheric activity, the baseline solution is more dependent on the double-difference ionosphere-free combined observation equation to eliminate the ionospheric error. The ionosphere can be constrained to obtain the correct integer ambiguity, improve the accuracy of extracting atmospheric delay, and thus improve the positioning accuracy of network real-time differential positioning in low-latitude areas or areas with variable climates. BRIEF DESCRIPTION OF THE DRAWINGS

[0083] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0084] Figure 1 A flowchart of a network real-time differential positioning method provided in an embodiment of the present application;

[0085] Figure 2 A schematic diagram of a process for constructing an initial observation equation for a network real-time differential positioning method provided in an embodiment of the present application;

[0086] Figure 3 A schematic diagram of a process for obtaining a double-difference non-combined observation model in a network real-time differential positioning method provided in an embodiment of the present application;

[0087] Figure 4 A schematic diagram of a process for constructing a double-difference ionosphere-free combined observation model for a network real-time differential positioning method provided in an embodiment of the present application;

[0088] Figure 5 A schematic diagram of a flow chart of determining double-difference tropospheric delay, double-difference integer ambiguity and double-difference ionospheric delay in a network real-time differential positioning method provided in an embodiment of the present application;

[0089] Figure 6 A schematic diagram of a process for determining double-difference tropospheric delay in a network real-time differential positioning method provided in an embodiment of the present application;

[0090] Figure 7 A schematic diagram of a flow chart of updating a second weight in a network real-time differential positioning method provided in an embodiment of the present application;

[0091] Figure 8 Another schematic diagram of a flow chart of updating the second weight of the network real-time differential positioning method provided in an embodiment of the present application;

[0092] Fig. 9 Another schematic diagram of a process for updating the second weight of the network real-time differential positioning method provided in an embodiment of the present application;

[0093] Fig.10 A module structure diagram of a network real-time differential positioning device provided in an embodiment of the present application;

[0094] Fig.11 A schematic diagram of the structure of a computer device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0095] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. It should be understood that the drawings in the present application only serve the purpose of explanation and description and are not used to limit the scope of protection of the present application. In addition, it should be understood that the schematic drawings are not drawn in real proportion. The flowchart used in this application shows the operations implemented according to some embodiments of the present application. It should be understood that the operations of the flowchart can be implemented out of sequence, and the steps without logical context can be reversed in order or implemented simultaneously. In addition, those skilled in the art can add one or more other operations to the flowchart under the guidance of the content of the present application, or remove one or more operations from the flowchart.

[0096] In addition, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but merely represents the 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 making creative work belong to 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 existence of the features declared thereafter, but does not exclude the addition of other features.

[0098] At present, network RTK usually uses double-difference non-combined observation equations for baseline solution. For low-latitude areas close to the equator, the intensity of solar radiation is higher than that in mid- and high-latitude areas, and the electron density of the ionosphere varies more, which has a greater impact on the propagation of GNSS signals. In addition, the vertical structure of the ionosphere in low-latitude areas is different from that in mid- and high-latitude areas, which will reduce the applicability of the ionosphere model and thus affect the positioning accuracy. In addition, the stability of the ionosphere in areas with variable climates is poor. When performing baseline solution in low-latitude areas or areas with variable climates, ambiguity is easily affected by the active ionosphere, resulting in fixed errors, which affects the positioning accuracy of network RTK in low-latitude areas or areas with variable climates.

[0099] Based on the above problems, the embodiment of the present application proposes a network real-time differential positioning method, which adds a double-difference ionosphere-free combined observation model to the double-difference non-combined observation model, and forms an observation equation based on the double-difference non-combined observation equation with a first weight and the double-difference ionosphere-free combined observation equation with a second weight and participates in the baseline solution to obtain the tropospheric delay, integer ambiguity and ionospheric delay. The weight of the double-difference ionosphere-free combined observation equation in the observation equation is adaptively adjusted in real time according to the activity of the ionosphere, the ionosphere is constrained to obtain the correct integer ambiguity, and then the correct atmospheric delay is obtained, thereby improving the positioning accuracy of network real-time differential positioning in low-latitude areas or areas with variable climates.

[0100] Figure 1 The flowchart of the network real-time differential positioning method provided in the embodiment of the present application is shown in FIG. 1 , and the execution subject of the method can be any computer device with computing processing capabilities. Figure 1 As shown, the method includes:

[0101] S101. Obtain global navigation satellite system observation values ​​of each satellite at each frequency point, where the global navigation satellite system observation values ​​include pseudorange observation values ​​and carrier phase observation values.

[0102] Optionally, multiple reference stations are established to form a reference station network. Multiple reference stations are used as receivers to receive the global navigation satellite system (GNSS) signals of each satellite at each frequency point in real time to obtain the GNSS observation value of each satellite at each frequency point. Each reference station transmits the GNSS observation value of each satellite at each frequency point to the computer equipment of the data processing center in real time. The GNSS observation value includes the pseudorange observation value P i and the carrier phase observation φ i .

[0103] GNSS signals will be affected by satellite errors, propagation path errors and receiver errors when they arrive from the satellite to the receiver. Satellite errors include satellite clock errors, satellite hardware delays and orbital delays; propagation path errors include ionospheric delays, tropospheric delays and atmospheric refraction delays such as multipath errors; receiver errors include receiver clock errors, receiver hardware delays and relativistic effects.

[0104] Among them, the pseudorange observation value P i The measured distance is obtained by multiplying the propagation time of the GNSS signal transmitted by the satellite to the receiver antenna by the speed of light. Due to the clock error and atmospheric refraction delay, this distance is not the real distance. iIt is the phase difference between the satellite carrier signal received by the receiver and the reference carrier signal generated by the receiver oscillator, and i is any frequency point.

[0105] S102. Constructing an initial observation equation based on 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 ionospheric-free combined observation equation with a second weight, wherein the first weight is greater than the second weight.

[0106] Optionally, the computer equipment of the data processing center constructs a Delaunay triangulation network according to the coordinates of each reference station obtained in advance to obtain a baseline list, and constructs an initial observation equation based on the double-difference non-combined observation model and the double-difference ionosphere-free combined observation model according to the GNSS observation values ​​of each satellite at each frequency point. The initial observation equation includes 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.

[0107] That is to say, before the baseline solution of the starting epoch, the weight of the double-difference non-combined observation equation in the constructed initial observation equation is greater than the weight of the double-difference ionosphere-free combined observation equation, so that when the baseline solution is performed at the starting epoch based on the initial observation equation, it mainly depends on the double-difference non-combined observation equation in the initial observation equation. Among them, the starting epoch is a specific moment in GNSS, which serves as the reference point for time measurement and time epoch information.

[0108] S103. Perform baseline solution according to the initial observation equation to determine 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, and update the second weight 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-combined observation equation with a larger first weight and the double-difference non-ionosphere combined observation equation with a smaller second weight in the initial observation equation are combined, and the baseline of the starting epoch is mainly solved by the double-difference non-combined 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 Among them, i is any frequency point, and n is any satellite.

[0110] Double difference ionospheric delay of each satellite at the first frequency It can characterize the ionospheric activity of the area to be positioned under the current climate conditions, based on the double difference ionospheric delay of each satellite at the first frequency point. The ionospheric activity of the area to be positioned under the current climate conditions is characterized, and the second weight of the double-difference ionosphere-free combined observation equation is updated in the next epoch of the starting epoch to obtain the target observation equation, and the baseline is solved based on the target observation equation in the next epoch of the starting epoch. In each subsequent epoch, the double-difference ionospheric delay of each satellite at the first frequency point solved in the previous epoch is calculated. The second weight of the double-difference ionosphere-free combined observation equation is updated iteratively in real time to obtain a new target observation equation. The ionospheric activity is positively correlated with the second weight of the double-difference ionosphere-free combined observation equation, that is, the higher the ionospheric activity, the greater the second weight of the double-difference ionosphere-free combined observation equation, so that in the baseline solution process of the next epoch of the current epoch, the double-difference ionosphere-free combined observation equation in the target observation equation is more dependent. The lower the ionospheric activity, the smaller the second weight of the double-difference ionosphere-free combined observation equation, so that in the baseline solution process of the next epoch of the current epoch, the double-difference non-combined observation equation in the target observation equation is more dependent.

[0111] It is worth noting that the double-difference ionosphere-free combined observation equation can eliminate the influence of ionospheric activity, while amplifying the noise and multipath errors of the observations. In the ionospheric quiet period with low ionospheric activity, amplifying the noise and multipath errors of the observations will have a major negative effect on the baseline solution. In the ionospheric active period with high ionospheric activity, the ionospheric delay error will have a major negative effect on the baseline solution compared with the noise and multipath errors of the observations. At this time, amplifying the noise and multipath errors of the observations is acceptable.

[0112] By setting the ionospheric activity to be positively correlated with the second weight of the double-difference ionosphere-free combined observation equation, the baseline solution is more dependent on the double-difference non-ionosphere combined observation equation in the target observation equation during the ionospheric quiet period with low ionospheric activity, avoiding the noise and multipath errors of the amplified observation values. During the ionospheric active period with high ionospheric activity, the baseline solution is more dependent on the double-difference ionosphere-free combined observation equation in the target observation equation to eliminate the ionospheric error.

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

[0114] Optionally, a baseline solution is performed at each epoch based on the iteratively updated target observation equation to extract the double-difference tropospheric delay at each epoch And the double difference ionospheric delay of each satellite at the first frequency point According to the double-difference tropospheric delay And the double difference ionospheric delay of each satellite at the first frequency point Determine atmospheric delay. The computer equipment in the data processing center performs atmospheric modeling on the baseline atmospheric delay around the approximate coordinates uploaded by the user through the terminal, generates VRS data at the user's location, and sends the VRS data to the user terminal to achieve high-precision positioning of network RTK.

[0115] In this embodiment, the global navigation satellite system observation values ​​of each satellite at each frequency point sent by each reference station are received, including pseudorange observation values ​​and carrier phase observation values. According to the global navigation satellite system observation values ​​of each satellite at each frequency point, based on the double-difference non-combined observation model and the double-difference ionosphere-free combined observation model, an initial observation equation 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 is constructed. According to the double-difference non-combined observation equation with a larger first weight and the double-difference ionosphere-free combined observation equation with a smaller second weight in the initial observation equation, the baseline of the starting epoch is solved mainly depending on the double-difference non-combined observation equation in the initial observation equation to determine the double-difference tropospheric delay, the double-difference integer ambiguity corresponding to each frequency point of each satellite, and the double-difference ionosphere delay of each satellite at the first frequency point. Based on the ionospheric activity of the area to be positioned under the current climate conditions represented by the double-difference ionosphere delay of each satellite at the first frequency point, the second weight of the double-difference ionosphere-free combined observation equation is updated to obtain the target observation equation. The baseline solution is performed again based on the target observation equation to determine the atmospheric delay, and the atmospheric modeling is performed for the baseline atmospheric delay around the approximate coordinates. The virtual mobile station data is generated and sent to the user terminal to achieve high-precision network real-time differential positioning. By adding a 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 used to form the observation equation and participate in the baseline solution. The weight of the double-difference ionosphere-free combined observation equation in the observation equation is adjusted adaptively in real time according to the activity of the ionosphere, so that the baseline solution is more dependent on the double-difference non-combined observation equation during the ionospheric quiet period with low ionospheric activity, avoiding the noise and multipath errors of the observation values ​​being amplified. During the ionospheric active period with high ionospheric activity, the baseline solution is more dependent on the double-difference ionosphere-free combined observation equation to eliminate the ionospheric error. The ionosphere can be constrained to obtain the correct integer ambiguity, improve the accuracy of extracting atmospheric delay, and thus improve the positioning accuracy of network real-time differential positioning in low-latitude areas or areas with variable climates.

[0116] The following is a detailed description of the process of constructing the initial observation equation based on the observation values ​​of each global navigation satellite system.

[0117] Figure 2A schematic diagram of the process of constructing the initial observation equation of the network real-time differential positioning method provided in the embodiment of the present application, such as Figure 2 As shown, the step of constructing the initial observation equation according to the observation values ​​of each global navigation satellite system in the above step S102 includes:

[0118] S201. Perform double difference operation according to global navigation satellite system observation values ​​to obtain a double difference non-combined observation model, and construct 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, wherein the first observation noise variance is used to characterize a first weight; the double difference non-combined observation model includes an expression for a double difference pseudorange observation value and an expression for a double difference carrier phase observation value.

[0119] Optionally, since the GNSS signal from the satellite to the receiver will be interfered by the satellite error, propagation path error and receiver error, taking one satellite as an example, the pseudo-range observation value P in the GNSS observation value at each frequency point is expressed based on the following formula (1) and formula (2): i and the carrier phase observation value φ i :

[0120]

[0121] Among them, P i is the pseudorange observation value of the ith frequency point, φ i is the carrier phase observation value of the ith frequency point, ρ is the geometric distance from the satellite to the receiver, c is the speed of light, dt s is the satellite clock error, dt r is the receiver clock error, T is the tropospheric delay, I is the ionospheric delay of the first frequency point, μ i is the ratio coefficient of the ionospheric delay at the i-th frequency point to the ionospheric delay at the first frequency point, μ i I is the ionospheric delay at the i-th frequency point, λ i is the wavelength of the ith frequency point of the GNSS signal, N i is the integer ambiguity of the carrier phase observation value at the i-th frequency point, δP i,r is the hardware delay of the pseudorange observation value of the i-th frequency point at the receiver end, is the hardware delay of the pseudorange observation value of the i-th frequency point at the satellite end, ∈ pi is the pseudo-range observation noise of the ith frequency point, ∈ Li is the carrier phase observation noise at the i-th frequency point.

[0122] According to the pseudo-range observation value P in the GNSS observation value of each satellite at each frequency point i and the carrier phase observation value φ i, through double difference operation to eliminate satellite clock error, receiver clock error and hardware delay errors, construct the double difference non-combined observation model shown in the following formula (3), including the expression of the double difference pseudorange observation value above and the expression of the double difference carrier phase observation value below:

[0123]

[0124] in, 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 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, is the double difference carrier phase observation value at the i-th frequency point, λ i is the wavelength of the ith frequency point of the GNSS signal, is the double difference integer ambiguity of the carrier phase observation value at the i-th frequency point, is the double-difference carrier phase observation noise at the i-th frequency point.

[0125] Due to the double difference geometric distance from satellite to receiver The double-difference tropospheric delay can be obtained by calculating the distance between the known reference station (receiver) coordinates and the satellite coordinates. and the double-difference tropospheric projection function It can also be obtained by calculation. The parameters to be estimated 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 double-difference non-combined observation equation shown in the following formula (4) is derived:

[0126]

[0127] in:

[0128]

[0129] Among them, S represents the satellite, n is the number of satellites, i and j represent different frequency points, and are the carrier phase observation value and pseudorange observation value of each satellite at the i-th frequency point and the j-th frequency point, respectively. is the double difference ionospheric delay of each satellite at the first frequency point, and are the double-difference integer ambiguities of the carrier phase observations of each satellite at the i-th and j-th frequency points, λ i and λ j are the wavelengths of the GNSS signal at the i-th and j-th frequencies, is the double-difference zenith tropospheric wet delay, is the double difference tropospheric dry delay, μ i and μ j are the ratio coefficients of the ionospheric delay at the i-th frequency point and the j-th frequency point to the ionospheric delay at the first frequency point, is the double-difference tropospheric projection function of each satellite.

[0130] Based on the double-difference non-combined observation model shown in formula (3) and the double-difference non-combined observation equation shown in formula (4), the first observation noise variance R of the double-difference non-combined observation equation is derived: k , the first observation noise variance R k As shown in the following formula (5):

[0131]

[0132] Among them, R k is the first observation noise variance of the double-difference non-combined observation equation, which can characterize the first weight of the double-difference non-combined observation equation when filtering in the initial observation equation. and are the variances of pseudorange observation noise of each satellite at the i-th frequency point and the j-th frequency point, and are the variances of the carrier phase observation noise of each satellite at the i-th frequency point and the j-th frequency point respectively.

[0133] S202. According to the double-difference non-combined observation model, a double-difference ionosphere-free combined observation model is constructed. According to the double-difference ionosphere-free combined observation model, a double-difference ionosphere-free combined observation equation and a second observation noise variance of the double-difference ionosphere-free combined observation equation are constructed, and the second observation noise variance is used to characterize the second weight. The double-difference ionosphere-free combined observation model includes an expression for a double-difference ionosphere-free combined pseudorange observation value and an expression for a double-difference ionosphere-free combined carrier phase observation value.

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

[0135]

[0136] in, is the double-difference ionosphere-free combined pseudorange 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, is the double-difference zenith tropospheric wet delay, is the double-difference ionosphere-free combined pseudorange observation noise, is the double-difference ionospheric-free combined carrier phase observation value, λ1 and λ2 are the wavelengths of the first and second frequency points 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 the double-difference integer ambiguities of the carrier phase observations of the first frequency point and the second frequency point, respectively. is the double-difference ionospheric-free combined carrier phase observation noise.

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

[0138]

[0139] Where n is the number of satellites, i and j represent different frequency points, and are the double-difference integer ambiguities of the carrier phase observations of each satellite at the i-th frequency and the j-th frequency, λ1 and λ2 are the wavelengths of the first and second frequency points of the GNSS signal, is the double-difference zenith tropospheric wet delay, is the double-difference tropospheric dry delay, is the double-difference tropospheric projection function of each satellite.

[0140] Based on the double-difference ionosphere-free combined observation model shown in formula (6) and the double-difference ionosphere-free combined observation equation shown in formula (7), the second observation noise variance R of the double-difference ionosphere-free combined observation equation is derived: kIF , the second observation noise variance R kIF As shown in the following formula (8):

[0141]

[0142] Among them, R kIFis the second observation noise variance of the double-difference ionosphere-free combined observation equation, which can characterize the second weight of the double-difference ionosphere-free combined observation equation when filtering in the initial observation equation. is the variance of pseudorange observation noise of each satellite, is 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, the double-difference ionospheric-free combined observation equation, and the second observation noise variance.

[0144] Optionally, according to the double-difference non-combined observation equation shown in formula (4) and the first observation noise variance R of the double-difference non-combined observation equation shown in formula (5), k , the second observation noise variance R of the double-difference ionosphere-free combined observation equation shown in formula (7) and the double-difference ionosphere-free combined observation equation shown in formula (8) kIF , construct the initial observation equation. Among them, the first observation noise variance R in the initial observation equation k The first weight represented is much larger than the second observation noise variance R kIF The second weight characterized by , makes it possible to mainly rely on the double difference non-combined observation equation shown in formula (4) when filtering and solving the initial observation equation.

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

[0146] The following describes in detail the process of performing double difference calculation based on the observation values ​​of each global navigation satellite system to obtain the double difference non-combined observation model.

[0147] Figure 3A schematic diagram of a process for obtaining a double-difference non-combined observation model for a network real-time differential positioning method provided in an embodiment of the present application, such as Figure 3 As shown, the step of performing double difference operation according to the global navigation satellite system observation value in the above step S201 to obtain the double difference non-combined observation model includes:

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

[0149] Optionally, for each pseudo-range observation value P in the GNSS observation value of each satellite at each frequency point, i Perform the first double difference operation to obtain the double difference pseudorange observation value The initial expression of is based on the following formula (9) to express the double-difference pseudorange observation value

[0150]

[0151] in, 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 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 pseudo-range observation noise at the i-th frequency point.

[0152] Double-difference tropospheric delay Includes double-difference tropospheric dry delay and double-difference tropospheric wet delay Double-difference tropospheric wet delay is the double-difference tropospheric projection function and double-difference zenith tropospheric wet delay The double difference tropospheric delay is expressed based on the following formulas (10) and (11): and double-difference tropospheric wet delay

[0153]

[0154] in, 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 projection function, is the double-difference zenith tropospheric wet delay.

[0155] Substituting the above formulas (10) and (11) into the above formula (9), we can obtain the double-difference pseudorange observation value: The expression of double-difference pseudorange observations The expression of includes at least the double difference geometric distance from satellite to receiver Double difference ionospheric delay and double difference zenith tropospheric wet delay The double-difference pseudorange observation value is expressed based on the following formula (12):

[0156]

[0157] in, 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 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. Perform a second double difference operation on each carrier phase observation value in the global navigation satellite system observation value to obtain an expression of the double difference carrier phase observation value, wherein the expression of the double difference carrier phase observation value includes at least a double difference geometric distance, a double difference ionospheric delay, a double difference integer ambiguity and a double difference zenith tropospheric wet delay.

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

[0160]

[0161] in, 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 ith frequency point of the GNSS signal, is the double difference integer ambiguity of the carrier phase observation value at the i-th frequency point, is the double-difference carrier phase observation noise at the i-th frequency point.

[0162] Substituting the above formula (10) and formula (11) into the above formula (13), we can get the double difference carrier phase observation value: The expression of double difference carrier phase observation The expression of includes at least the double difference geometric distance from satellite to receiver Double difference ionospheric delay, double difference integer ambiguity and double-difference zenith tropospheric wet delay The double-difference carrier phase observation value is expressed based on the following formula (14):

[0163]

[0164] in, 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 dry delay, is the double-difference tropospheric projection function, is the double difference zenith tropospheric wet delay, λ i is the wavelength of the ith frequency point of the GNSS signal, is the double difference integer ambiguity of the carrier phase observation value at the i-th frequency point, is the double-difference carrier phase observation noise at the i-th frequency point.

[0165] S303. Obtain a double-difference non-combined observation model according to an expression of a double-difference pseudorange observation value and an expression of a double-difference carrier phase observation value.

[0166] Optionally, by calculating the pseudo-range observation value P of each satellite in the GNSS observation value at each frequency point i Perform the first double difference operation and calculate the phase observation value φ of each carrier i The second double difference operation is performed to eliminate errors such as satellite clock error, receiver clock error and hardware delay, and to weaken the error influence of ionospheric delay and tropospheric delay. According to the double difference pseudorange observation value shown in the above formula (12): The expression of and the double-difference carrier phase observation value shown in the above formula (14) The expression of is used to construct the double-difference non-combined observation model shown in the following formula (3):

[0167]

[0168] in, 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 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, is the double difference carrier phase observation value at the i-th frequency point, λ i is the wavelength of the ith frequency point of the GNSS signal, is the double difference integer ambiguity of the carrier phase observation value at the i-th frequency point, is the double-difference carrier phase observation noise at the i-th frequency point.

[0169] In this embodiment, by performing the first double difference operation and the second double difference operation on each pseudorange observation value and each carrier phase observation value in the global navigation satellite system observation value, the expression of the double difference pseudorange observation value and the expression of the double difference carrier phase observation value are obtained, and the expression of the double difference pseudorange 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 ionospheric delay and tropospheric delay is weakened. Based on the expression of the double difference pseudorange observation value and the expression of the double difference carrier phase observation value, the double difference non-combined observation model is accurately constructed.

[0170] The following is a detailed description of the process of constructing a double-difference ionospheric-free combined observation model based on the double-difference non-combined observation model.

[0171] Figure 4 A schematic diagram of a flow chart of a double-difference ionospheric-free combined observation model for a network real-time differential positioning method provided in an embodiment of the present application, such as Figure 4 As shown, the step of constructing a double-difference ionospheric-free combined observation model according to the double-difference non-combined observation model in the above step S202 includes:

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

[0173] Optionally, according to the above formula (12), the double-difference pseudorange observation value The expression of double-difference pseudorange observation value is In the expression of, determine the double difference pseudorange observation value of the first frequency point And the double difference pseudorange observation value of the second frequency point

[0174] S402. Determine an expression for a double-difference ionospheric-free combined pseudorange observation value according to a double-difference pseudorange observation value of a first frequency point, a double-difference pseudorange observation value of a second frequency point, and a preset combination coefficient.

[0175] Optionally, according to the double-difference pseudo-range observation value of the first frequency point Double difference pseudorange observation value of the second frequency point And the first coefficient in the preset combination coefficient and the second coefficient The double-difference ionospheric-free combined pseudorange observation value is determined based on the following formula (15): The initial expression of is:

[0176]

[0177] in, is the double-difference ionosphere-free combined pseudorange 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 pseudorange observation value of the first frequency point, is the double difference pseudorange observation value of the second frequency point.

[0178] Substituting the above formula (12) into the above formula (15), we can obtain the double-difference ionospheric-free combined pseudorange observation value: The expression of , which eliminates the influence of the first-order ionospheric delay error, makes the double-difference ionospheric-free combined pseudorange observation value The expression of includes at least the double difference geometric distance from satellite to receiver and double-difference zenith tropospheric wet delay The double-difference ionospheric-free combined pseudorange observation value is expressed based on the following formula (16):

[0179]

[0180] in, is the double-difference ionosphere-free combined pseudorange 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, is the double-difference zenith tropospheric wet delay, is the double-difference ionospheric-free combined pseudorange observation noise.

[0181] S403. Determine 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 according to the expression of the double-difference carrier phase observation value.

[0182] Optionally, according to the above formula (14), the double difference carrier phase observation value The double-difference carrier phase observation value is In the expression of, determine 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

[0183] S404. Determine an expression for a double-difference ionospheric-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 a preset combination coefficient.

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

[0185]

[0186] in, is the double-difference ionospheric-free combined carrier phase 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 carrier phase observation value of the first frequency point, is the double-difference carrier phase observation value of the second frequency point.

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

[0188]

[0189] in, is the double-difference ionospheric-free combined carrier phase 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, is the double difference zenith tropospheric wet delay, λ1 and λ2 are the wavelengths of the first and second frequencies 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 the double-difference integer ambiguities of the carrier phase observations of the first frequency point and the second frequency point, respectively. is the double-difference ionospheric-free combined carrier phase observation noise.

[0190] S405. Obtain a double-difference ionospheric-free combined observation model according to an expression of a double-difference ionospheric-free combined pseudorange observation value and an expression of a double-difference ionospheric-free combined carrier phase observation value.

[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 a linear combination of preset combination coefficients, while the magnitude of the higher-order ionospheric delay error is small and has been eliminated in the previous double difference operation process. According to the above formula (16), the double-difference ionospheric-free combined pseudorange observation value The expression of the double-difference ionospheric-free combined carrier phase observation value of the above formula (18) The double-difference ionosphere-free combined observation model shown in the following formula (6) is constructed:

[0192]

[0193] in, is the double-difference ionosphere-free combined pseudorange 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, is the double-difference zenith tropospheric wet delay, is the double-difference ionosphere-free combined pseudorange observation noise, is the double-difference ionospheric-free combined carrier phase observation value, λ1 and λ2 are the wavelengths of the first and second frequency points 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 the double-difference integer ambiguities of the carrier phase observations of the first frequency point and the second frequency point, respectively. is the double-difference ionospheric-free combined carrier phase observation noise.

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

[0195] The following describes in detail the process of determining 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.

[0196] Figure 5 A schematic diagram of a flow chart of determining double-difference tropospheric delay, double-difference integer ambiguity, and double-difference ionospheric delay in a network real-time differential positioning method provided in an embodiment of the present application, such as Figure 5 As shown, the step of determining 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 in the above step S103 includes:

[0197] S501. 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.

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

[0199] S502: Perform Kalman filtering according to the initial observation equation, and use the least squares ambiguity reduction correlation adjustment method to determine the double-difference integer ambiguity corresponding to each frequency point of each satellite.

[0200] Optionally, according to the first weight and the second weight in the initial observation equation, the initial observation equation is subjected to a baseline solution of a Kalman filter, and the integer ambiguity is fixed by a least-squares ambiguity reduction correlation adjustment method (Lambda for short) to obtain the double-difference integer ambiguity of the carrier phase observation value corresponding to each frequency point of each satellite. and

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

[0202] Optionally, assign i and j to 1 and 2 respectively to obtain the double difference integer ambiguity corresponding to the first frequency point of each satellite And the double difference integer ambiguity corresponding to the second frequency point of each satellite And solve the initial observation equation to obtain the carrier phase observation value corresponding to the first frequency point of each satellite And the carrier phase observation value corresponding to the second frequency point of each satellite

[0203] S504. Determine the double-difference ionospheric delay of each satellite at the first frequency point based on the double-difference integer ambiguity and carrier phase observation value corresponding to the first frequency point of each satellite and the double-difference integer ambiguity and carrier phase observation value corresponding to the second frequency point of each satellite.

[0204] Optionally, according to the double difference integer ambiguity corresponding to the first frequency point of each satellite The double difference integer ambiguity corresponding to the second frequency point of each satellite The carrier phase observation value corresponding to the first frequency point of each satellite The carrier phase observation value corresponding to the second frequency point of each satellite The wavelength λ1 of the first frequency point of the GNSS signal, the wavelength λ2 of the second frequency point of the GNSS signal, and the second coefficient in the preset combination coefficient Based on the following formula (19), the geometry-free (GF) combination is used to extract the double difference ionospheric delay of each satellite at the first frequency point.

[0205]

[0206] in, is the double difference ionospheric delay of each satellite at the first frequency point, λ1 and λ2 are the wavelengths of the first and second frequency points of the GNSS signal, respectively. and are the carrier phase observation values ​​corresponding to the first and second frequencies of each satellite, and are the double-difference integer ambiguities corresponding to the first and second frequencies of each satellite, 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.

[0207] In this embodiment, according to the first weight and the second weight in the initial observation equation, the initial observation equation is solved to obtain the double difference zenith tropospheric wet delay, and the double difference tropospheric delay is obtained based on the double difference zenith tropospheric wet delay. According to the first weight and the second weight in the initial observation equation, the initial observation equation is subjected to a baseline solution of a Kalman filter, and the integer ambiguity is fixed by the least squares ambiguity reduction correlation adjustment method to obtain the double difference integer ambiguity of the carrier phase observation value corresponding to each frequency point of each satellite. The double difference integer ambiguity and carrier phase observation value corresponding to the first frequency point of each satellite and the double difference integer ambiguity and carrier phase observation value corresponding to the second frequency point of each satellite are determined, and according to the double difference integer ambiguity and carrier phase observation value corresponding to the first frequency point of each satellite and the double difference integer ambiguity and 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 extracted by using a geometrically independent combination. Based on the double difference integer ambiguity obtained by accurate solution, the double difference ionospheric delay of each satellite at the first frequency point is accurately extracted, and the influence of the ionospheric delay error is suppressed.

[0208] The following is a detailed description of the process of determining the double-difference tropospheric delay based on the double-difference zenith tropospheric wet delay.

[0209] Figure 6 A schematic diagram of a flow chart of determining double-difference tropospheric delay in a network real-time differential positioning method provided in an embodiment of the present application, such as Figure 6 As shown, the step of determining the double difference tropospheric delay according to the double difference zenith tropospheric wet delay in the above step S501 includes:

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

[0211] Optionally, a global mapping function model (GMF), i.e., a tropospheric delay mapping model, is pre-set in the computer equipment of the data processing center. Based on the preset tropospheric delay mapping model, a double-difference tropospheric projection function is calculated. According to the double-difference tropospheric projection function and the double-difference zenith tropospheric wet delay obtained by baseline solution of the initial observation equation Based on formula (11), the double difference tropospheric projection function Double-difference zenith tropospheric wet delay The double-difference tropospheric wet delay

[0212]

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

[0214] S602: Determine a double-difference tropospheric dry delay according to a tropospheric delay mapping model, and use the sum of the double-difference tropospheric dry delay and the double-difference tropospheric wet delay as the double-difference tropospheric delay.

[0215] Optionally, based on a preset tropospheric delay mapping model, a double-difference tropospheric dry delay is calculated: Based on formula (10), the double-difference tropospheric dry delay Double-difference tropospheric wet delay The double-difference tropospheric delay

[0216]

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

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

[0219] The following describes in detail the process of updating the second weight according to the double-difference ionospheric delay of each satellite at the first frequency point.

[0220] Figure 7 A schematic diagram of a flow chart of updating the second weight of the network real-time differential positioning method provided in the embodiment of the present application, such as Figure 7 As shown, in the above step S103, the step of updating the second weight according to the double difference ionospheric delay of each satellite at the first frequency point includes:

[0221] S701. Determine the ionospheric activity index of the current epoch based on the double-difference ionospheric delay of each satellite at the first frequency point; the ionospheric activity index includes the proportion of ionospheric active satellites, the ionospheric delay change rate, and the ionospheric delay mean error.

[0222] Optionally, according to the double difference ionospheric delay of each satellite at the first frequency point Calculate the current epoch's ionospheric active satellite ratio, ionospheric delay change rate, and ionospheric delay error std, that is, determine the ionospheric activity index of the current epoch. Among them, the ionospheric active satellite is a satellite whose absolute value of the double difference ionospheric delay at the first frequency point is greater than the preset active threshold, that is, if the absolute value of the double difference ionospheric delay of the satellite at the first frequency point is greater than the preset active threshold, then the satellite is determined to be an ionospheric active satellite, and the number of ionospheric active satellites is counted, and the quotient of the number of ionospheric active satellites and the number of all satellites is taken as the ionospheric active satellite ratio.

[0223] According to the double difference ionospheric delay of each satellite at the first frequency The mean ionospheric delay is determined by mean calculation, and the variance is calculated based on the mean ionospheric delay to obtain the double difference ionospheric delay of each satellite at the first frequency point. The mean error is the square root of the variance, and the square root of the variance is taken to get the mean error std of the ionospheric delay.

[0224] S702: Determine and update a second weight of the next epoch of the current epoch based on the ionospheric activity index.

[0225] Optionally, according to the corresponding relationship between the positive correlation between the ionospheric activity index and the second weight, the second weight of the next epoch of the current epoch is determined, and the second weight is updated in the next epoch of the current epoch. If the ionospheric activity index is high, the second weight is increased in the next epoch of the current epoch, and vice versa, if the ionospheric activity index is low, the second weight is reduced in 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 of the double-difference ionosphere-free combined observation equation in the initial observation equation is kIF 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] Among them, 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 Negatively correlated with the second weight, if the ionospheric activity index is high, by increasing the second weight, the second observation noise variance of the double-difference ionosphere-free combined observation equation in the target observation equation can be reduced. 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 reducing the second weight. Avoid the negative impact of amplified observation noise and multipath errors caused by over-reliance on the double-difference ionosphere-free combined observation equation.

[0230] In this embodiment, the proportion of active satellites in the ionosphere, the rate of change of ionospheric delay and the error in ionospheric delay of each satellite at the first frequency point are calculated to determine the ionospheric activity index of the current epoch. There is a positively correlated correspondence between the ionospheric activity index and the second weight, and the second weight of the next epoch of the current epoch is determined and updated based on the corresponding relationship. If the ionospheric activity index is 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 combined observation equation in the target observation equation, and to suppress the influence of the ionospheric delay error when the ionosphere is active. If the ionospheric activity index is 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 combined observation equation in the target observation equation, and to avoid amplifying the observation noise and multipath errors.

[0231] The following describes in detail the process of determining and updating the second weight of the next epoch of the current epoch based on the ionospheric activity index.

[0232] Figure 8 Another flowchart of updating the second weight of the network real-time differential positioning method provided in the embodiment of the present application is as follows: Figure 8 As shown, 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 above step S702 includes:

[0233] S801, determine the first quotient of the proportion of active satellites in the ionosphere and a preset threshold value of the proportion of active satellites in the ionosphere, the second quotient of the ionosphere delay change rate and a preset threshold value of the ionosphere delay change rate, and the third quotient of the ionosphere delay error and a preset threshold value of the ionosphere delay error.

[0234] Optionally, a first quotient of the ionospheric active satellite ratio and a preset ionospheric active satellite ratio threshold ratioThres is calculated. The second quotient of the ionospheric delay change rate rate and the preset ionospheric delay change rate threshold rateThres and the third quotient of the ionospheric delay error std and the preset ionospheric delay error threshold stdThres

[0235] S802: Taking the product of 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 ratio and a preset ionospheric active satellite ratio threshold ratioThres is calculated. The second quotient of the ionospheric delay change rate rate and the preset ionospheric delay change rate threshold rateThres The third quotient of the ionospheric delay error std and the preset ionospheric delay error threshold stdThres The product of is used as the second weight w of the next epoch of the current epoch, and the second weight of the current epoch is updated to 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 formula (21):

[0237]

[0238] Among them, w is the second weight of the next epoch of the current epoch, ratio is the ratio of active satellites in the ionosphere, ratioThres is the preset threshold of the ratio of active satellites in the ionosphere, rate is the rate of change of ionospheric delay, rateThres is the preset threshold of the rate of change of ionospheric delay, std is the mean error of ionospheric delay, and stdThres is the preset threshold of the mean error of ionospheric delay.

[0239] In this embodiment, the first quotient of the proportion of active satellites in the ionosphere and the preset threshold of the proportion of active satellites in the ionosphere, the second quotient of the rate of change of ionosphere delay and the preset threshold of the rate of change of ionosphere delay, and the third quotient of the mean error of ionosphere delay and the preset threshold of the mean error of ionosphere delay are calculated, and 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. By respectively presetting the threshold of the proportion of active satellites in the ionosphere, the threshold of the rate of change of ionosphere delay, and the threshold of the mean error of ionosphere delay, the accuracy of judging the activity of the ionosphere is improved, and the probability of misjudgment is reduced.

[0240] Fig. 9 Another flow chart of updating the second weight of the network real-time differential positioning method provided in the embodiment of the present application is as follows: Fig. 9 As shown, 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 above step S702 includes:

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

[0242] Optionally, the activity state of the ionosphere is determined according to the relationship between the ratio of active satellites in the ionosphere and a preset ratioThres ratio of active satellites in the ionosphere, the relationship between the rate of change of ionosphere delay and a preset rateThres ratio of ionosphere delay, and the relationship between the std of ionosphere delay and a preset stdThres threshold of ionosphere delay. If the ratio of active satellites in the ionosphere, the rate of change of ionosphere delay and the std of ionosphere delay in the current epoch are all greater than their respective corresponding thresholds, it is determined that the ionosphere is in an active period.

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

[0244] Calculate the first difference ratio-ratioThres between the ratio of active satellites in the ionosphere and the preset threshold ratioThres of active satellites in the ionosphere, the second difference rate-rateThres between the rate of change of ionosphere delay and the preset threshold rateThres of change of ionosphere delay, and the third difference std-stdThres between the mean error of ionosphere delay std and the preset threshold stdThres of mean error of ionosphere delay, and determine and update the second weight w of the next epoch of the current epoch. The larger the first difference ratio-ratioThres, the second difference rate-rateThres or the third difference std-stdThres, the larger the second weight w of the next epoch of the current epoch.

[0245] S902. Otherwise, determine that the ionosphere is in a quiet period, and use the second weight of the current epoch as the second weight of the next epoch of the current epoch.

[0246] Optionally, if any of the ionospheric active satellite ratio, the ionospheric delay change rate or the ionospheric delay error std in 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 proportion of active satellites in the ionosphere ratio is less than or equal to the preset ionosphere active satellite proportion threshold ratioThres, or the ionosphere delay change rate reate is less than or equal to the preset ionosphere delay change rate threshold rateThres, or the ionosphere delay error std is less than or equal to the preset ionosphere delay error threshold stdThres, then it is determined that the ionosphere is in a quiet period. At this time, there is no need to update the second weight, and the second weight of the current epoch is directly used as the second weight of the next epoch of the current epoch.

[0248] In this embodiment, the activity state of the ionosphere is determined based on the size relationship between the proportion of active satellites in the ionosphere and the preset threshold value of the proportion of active satellites in the ionosphere, the size relationship between the ionosphere delay change rate and the preset threshold value of the ionosphere delay change rate, and the size relationship between the ionosphere delay error and the preset threshold value of the ionosphere delay error. If the proportion of active satellites in the ionosphere, the ionosphere delay change rate, and the ionosphere delay error in the current epoch are all greater than their respective corresponding thresholds, it is determined that the ionosphere is in an active period. Calculate the first difference between the proportion of active satellites in the ionosphere and the preset threshold value of the proportion of active satellites in the ionosphere, the second difference between the ionosphere delay change rate and the preset threshold value of the ionosphere delay change rate, and the third difference between the ionosphere delay error and the preset threshold value of the ionosphere delay error, and determine and update the second weight of the next epoch of the current epoch based on the first difference, the second difference, and the third difference. If any of the percentage of active satellites in the ionosphere, the rate of change of ionosphere delay, or the error in ionosphere delay in the current epoch is less than or equal to the corresponding threshold, the ionosphere is determined to be in a quiet period, and there is no need to update the second weight. The second weight of the current epoch is used as the second weight of the next epoch of the current epoch. By setting each indicator in the ionosphere activity index to be greater than the corresponding threshold, the weight is increased, which reduces the probability of misjudgment of the ionosphere active period and quiet period, and improves the accuracy of the second weight update.

[0249] Specifically, if the proportion of active satellites in the ionosphere reate is less than or equal to the preset ionosphere active satellite proportion threshold ratioThres, or the ionosphere delay change rate reate is less than or equal to the preset ionosphere delay change rate threshold rateThres, or the ionosphere delay error std is less than or equal to the preset ionosphere delay error threshold stdThres, then it is determined that the ionosphere is in a quiet period. At this time, there is no need to update the second weight, and the second weight of the current epoch is directly used as the second weight of the next epoch of the current epoch.

[0250] Based on the same inventive concept, the embodiment of the present application also provides a network real-time differential positioning device corresponding to the network real-time differential positioning method. Since the principle of solving the problem by the device in the embodiment of the present application is similar to the above-mentioned network real-time differential positioning method in the embodiment of the present application, the implementation of the device can refer to the implementation of the method, and the repeated parts will not be repeated.

[0251] Fig.10 The module structure diagram of the network real-time differential positioning device provided in the embodiment of the present application is as follows: Fig.10 As shown, the device comprises:

[0252] The acquisition module 1001 is used to acquire the global navigation satellite system observation values ​​of each satellite at each frequency point, and the global navigation satellite system observation values ​​include pseudorange observation values ​​and carrier phase observation values.

[0253] The construction module 1002 is used to construct an initial observation equation based on the global navigation satellite system observation value, wherein the initial observation equation includes a double-difference non-combined observation equation with a first weight and a double-difference ionospheric-free combined observation equation with a second weight, wherein the first weight is greater than the second weight.

[0254] The determination module 1003 is used to perform a baseline solution according to the initial observation equation, determine 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, and update the second weight according to the double difference ionospheric delay of each satellite at the first frequency point to obtain the target observation equation.

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

[0256] As an optional implementation, the construction module 1002 is specifically used for:

[0257] According to the observation values ​​of the global navigation satellite system, a double difference operation is performed to obtain a double difference non-combined observation model, and a double difference non-combined observation equation and a first observation noise variance of the double difference non-combined observation equation are constructed according to the double difference non-combined observation model, and the first observation noise variance is used to characterize the first weight; the double difference non-combined observation model includes an expression for a double difference pseudorange observation value and an expression for a double difference carrier phase observation value.

[0258] According to the double-difference non-combined observation model, a double-difference ionosphere-free combined observation model is constructed. According to the double-difference ionosphere-free combined observation model, a double-difference ionosphere-free combined observation equation and a second observation noise variance of the double-difference ionosphere-free combined observation equation are constructed. The second observation noise variance is used to characterize the second weight. The double-difference ionosphere-free combined observation model includes an expression for a double-difference ionosphere-free combined pseudorange observation value and an expression for a double-difference ionosphere-free combined carrier phase observation value.

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

[0260] As an optional implementation, the construction module 1002 is specifically used for:

[0261] A first double difference operation is performed on each pseudorange observation value in the global navigation satellite system observation value to obtain an expression of the double difference pseudorange observation value, wherein the expression of the double difference pseudorange observation value at least includes a double difference geometric distance, a double difference ionospheric delay and a double difference zenith tropospheric wet delay.

[0262] A 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 the double difference carrier phase observation value, wherein the expression of the double difference carrier phase observation value includes at least a double difference geometric distance, a double difference ionospheric delay, a double difference integer ambiguity and a double difference zenith tropospheric wet delay.

[0263] According to the expression of double-difference pseudorange observation value and the expression of double-difference carrier phase observation value, the double-difference non-combined observation model is obtained.

[0264] As an optional implementation, the construction module 1002 is specifically used for:

[0265] 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.

[0266] An expression of a double-difference ionospheric-free combined pseudorange observation value is 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 a preset combination coefficient.

[0267] 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.

[0268] An expression of a double-difference ionospheric-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] According to the expression of double-difference ionospheric-free combined pseudorange observation value and the expression of double-difference ionospheric-free combined carrier phase observation value, the double-difference ionospheric-free combined observation model is obtained.

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

[0271] Based on the initial observation equation, the double difference zenith tropospheric wet delay is determined, and based on the double difference zenith tropospheric wet delay, the double difference tropospheric delay is determined.

[0272] Kalman filtering is performed according to the initial observation equation, and the double-difference integer ambiguity corresponding to each frequency point of each satellite is determined by the least squares ambiguity reduction correlation adjustment method.

[0273] Determine the double-difference integer ambiguity and carrier phase observation value corresponding to the first frequency point of each satellite and the double-difference integer ambiguity and carrier phase observation value corresponding to the second frequency point of each satellite.

[0274] The double-difference ionospheric delay of each satellite at the first frequency point is determined based on the double-difference integer ambiguity and carrier phase observation values ​​corresponding to the first frequency point of each satellite and the double-difference integer ambiguity and carrier phase observation values ​​corresponding to the second frequency point of each satellite.

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

[0276] The projection function of the double-difference troposphere is determined according to the preset tropospheric delay mapping, and the double-difference tropospheric wet delay is determined according to the projection function of the double-difference troposphere and the double-difference zenith tropospheric wet delay.

[0277] The double-difference tropospheric dry delay is determined according to the tropospheric delay mapping model, 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.

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

[0279] The ionospheric activity index of the current epoch is determined based on the double-difference ionospheric delay of each satellite at the first frequency point; the ionospheric activity index includes the proportion of ionospheric active satellites, the ionospheric delay change rate and the ionospheric delay mean error.

[0280] According to the ionospheric activity index, a second weight of the next epoch of the current epoch is determined and updated.

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

[0282] Determine a first quotient of the proportion of active satellites in the ionosphere and a preset threshold value of the proportion of active satellites in the ionosphere, a second quotient of the rate of change of ionospheric delay and a preset threshold value of the rate of change of ionospheric delay, and a third quotient of the error in ionospheric delay and a preset threshold value of the error in ionospheric delay.

[0283] 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.

[0284] As an optional implementation manner, the determination module 1003 is specifically configured to:

[0285] If the proportion of active satellites in the ionosphere is greater than the preset threshold value of the proportion of active satellites in the ionosphere, the rate of change of ionosphere delay is greater than the preset threshold value of the rate of change of ionosphere delay, and the mean error of ionosphere delay is greater than the preset threshold value of the mean error of ionosphere delay, then it is determined that the ionosphere is in an active period, and a first difference between the proportion of active satellites in the ionosphere and the preset threshold value of the proportion of active satellites in the ionosphere, a second difference between the rate of change of ionosphere delay and the preset threshold value of the rate of change of ionosphere delay, and a third difference between the mean error of ionosphere delay and the preset threshold value of the mean error of ionosphere delay 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.

[0286] Otherwise, it is determined that the ionosphere is in a quiet period, and the second weight of the current epoch is used as the second weight of the next epoch of the current epoch.

[0287] The present application also provides a computer device, such as Fig.11 1 is a schematic diagram of the structure of a computer device provided in an embodiment of the present application, including: a processor 111, a memory 112 and a bus 113. The memory 112 stores machine-readable instructions executable by the processor 111 (for example, Fig.10 In the device, the execution instructions corresponding to the acquisition module 1001, the construction module 1002, the determination module 1003 and the positioning module 1004 are obtained, 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] The embodiment of the present application further provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the network real-time differential positioning method in the above embodiment are executed.

[0289] Those skilled in the art can clearly understand that, for the convenience and simplicity of description, the specific working process of the system and device described above can refer to the corresponding process in the method embodiment, and will not be repeated in this application. In the several embodiments provided in this application, it should be understood that the disclosed system, device and method can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the modules is only a logical function division. There may be other division methods in actual implementation. For example, multiple modules or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interfaces, indirect coupling or communication connection of devices or modules, which can be electrical, mechanical or other forms.

[0290] In addition, each functional unit in each embodiment of the present application can be integrated into a processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. If the function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art or the part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including several instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, RandomAccess Memory), disk or optical disk and other media that can store program code.

[0291] The above are only specific implementation methods of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be covered by the protection scope of the present application.

Claims

1. A network real-time differential positioning method, characterized in that: include: Obtaining global navigation satellite system observation values ​​of each satellite at each frequency point, wherein the global navigation satellite system observation values ​​include pseudorange observation values ​​and carrier phase observation values; constructing an initial observation equation according to the global navigation satellite system observation value, the initial observation equation comprising a double-difference non-combined observation equation with a first weight and a double-difference ionospheric-free combined observation equation with a second weight, wherein the first weight is greater than the second weight; Performing a baseline solution according to the initial observation equation, determining 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 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; Network real-time differential positioning is performed based on the target observation equation.

2. The method according to claim 1, characterized in that The constructing of the initial observation equation according to the observation values ​​of each global navigation satellite system comprises: According to the global navigation satellite system observation value, a double difference operation is performed to obtain a double difference non-combined observation model, and according to the double difference non-combined observation model, the double difference non-combined observation equation and the first observation noise variance of the double difference non-combined observation equation are constructed, and the first observation noise variance is used to characterize the first weight; the double difference non-combined observation model includes an expression of a double difference pseudorange observation value and an expression of a double difference carrier phase observation value; According to the double-difference non-combined observation model, the double-difference ionosphere-free combined observation model is constructed; according to the double-difference ionosphere-free combined observation model, 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, and the second observation noise variance is used to characterize the second weight; the double-difference ionosphere-free combined observation model includes an expression of a double-difference ionosphere-free combined pseudorange observation value and an expression of a double-difference ionosphere-free combined carrier phase observation value; The initial observation equation is constructed according to the double-difference non-combined observation equation, the first observation noise variance, the double-difference ionospheric-free combined observation equation and the second observation noise variance.

3. The method according to claim 2, characterized in that The double difference operation is performed according to each of the global navigation satellite system observation values ​​to obtain a double difference non-combined observation model, including: Performing a first double difference operation on each pseudorange observation value in the global navigation satellite system observation value to obtain an expression of the double difference pseudorange observation value, wherein the expression of the double difference pseudorange observation value at least includes a double difference geometric distance, a double difference ionospheric delay, and a double difference zenith tropospheric wet delay; Performing a second double difference operation on each carrier phase observation value in the global navigation satellite system observation value to obtain an expression of the double difference carrier phase observation value, wherein 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; The double-difference non-combined observation model is obtained according to the expression of the double-difference pseudorange observation value and the expression of the double-difference carrier phase observation value.

4. The method according to claim 2, characterized in that: The step of constructing the double-difference ionospheric-free combined observation model according to the double-difference non-combined observation model comprises: Determine 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; Determine an expression for a double-difference ionospheric-free combined pseudorange observation value 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 a preset combination coefficient; Determine 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 according to the expression of the double-difference carrier phase observation value; Determine an expression of a double-difference ionospheric-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; According to the expression of the double-difference ionospheric-free combined pseudorange observation value and the expression of the double-difference ionospheric-free combined carrier phase observation value, the double-difference ionospheric-free combined observation model is obtained.

5. The method according to claim 3, characterized in that: The determining of 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 includes: 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; Kalman filtering is performed according to the initial observation equation, and the double-difference integer ambiguity corresponding to each frequency point of each satellite is determined by using the least squares ambiguity reduction correlation adjustment method; Determine the double-difference integer ambiguity and carrier phase observation value corresponding to the first frequency point of each satellite and the double-difference integer ambiguity and 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 according to the double-difference integer ambiguity and carrier phase observation value corresponding to the first frequency point of each satellite and the double-difference integer ambiguity and carrier phase observation value corresponding to the second frequency point of each satellite.

6. The method according to claim 5, characterized in that Determining the double difference tropospheric delay according to the double difference zenith tropospheric wet delay comprises: 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; A double-difference tropospheric dry delay is determined according to the tropospheric delay mapping model, and a sum of the double-difference tropospheric dry delay and the double-difference tropospheric wet delay is used as the double-difference tropospheric delay.

7. The method according to claim 1, characterized in that The updating of the second weight according to the double-difference ionospheric delay of each satellite at the first frequency point includes: Determine 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 includes a proportion of ionospheric active satellites, a rate of change of ionospheric delay, and a mean error of ionospheric delay; According to the ionospheric activity index, a second weight of the next epoch of the current epoch is determined and updated.

8. The method according to claim 7, characterized in that The determining and updating, according to the ionospheric activity index, a second weight of a next epoch of the current epoch comprises: Determine a first quotient of the ionospheric active satellite ratio and a preset ionospheric active satellite ratio 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; 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.

9. The method according to claim 7, characterized in that: The determining and updating, according to the ionospheric activity index, a second weight of a next epoch of the current epoch comprises: If the proportion of active satellites in the ionosphere is greater than a preset threshold value of the proportion of active satellites in the ionosphere, the rate of change of ionosphere delay is greater than a preset threshold value of the rate of change of ionosphere delay, and the error in ionosphere delay is greater than a preset threshold value of the error in ionosphere delay, it is determined that the ionosphere is in an active period, and a first difference between the proportion of active satellites in the ionosphere and the preset threshold value of the proportion of active satellites in the ionosphere, a second difference between the rate of change of ionosphere delay and the preset threshold value of the rate of change of ionosphere delay, and a third difference between the error in ionosphere delay and the preset threshold value of the error in ionosphere delay are determined, and a 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; Otherwise, it is determined that the ionosphere is in a quiet period, and the second weight of the current epoch is used as the second weight of the next epoch of the current epoch.

10. A computer device, characterized in that: include: A processor, a memory and a bus, wherein the memory stores machine-readable instructions executable by the processor, and 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 any one of claims 1 to 9.

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