GNSS full-band adaptive pseudo-range single-point positioning algorithm

Abstract

The invention discloses a GNSS full-band adaptive pseudo-range single-point positioning algorithm, and the algorithm comprises the steps: determining the priority of pseudo-range observed quantities participating in positioning calculation according to the quality of single-frequency pseudo-range and multi-frequency ionosphere-free combined pseudo-range observed quantities of each satellite navigation system under the full-band condition; and during real-time positioning calculation, the satellite receiver obtains the pseudo-range observed quantity with the highest priority for positioning calculation according to the received pseudo-range signal and the priority of the pseudo-range observed quantity determined under the full-band condition. According to the full-band adaptive pseudo-range single-point positioning algorithm provided by the invention, the optimal pseudo-range observed quantity can be adaptively adopted to carry out positioning calculation according to the pseudo-range signal received by the satellite receiver, so that the problem that the observed quantity cannot be fully utilized when the signal is lost in the traditional fixed-frequency or fixed-frequency combined pseudo-range single-point positioning algorithm is avoided; and the positioning performance is reduced, and positioning calculation cannot be carried out in a severe case. Besides, according to the full-band adaptive pseudo-range single-point positioning algorithm, the pseudo-range with the optimal observation quality is adopted at each epoch moment for positioning calculation, so that better positioning performance can be obtained.

Description

Technical Field

[0001] The present invention belongs to the field of satellite navigation and positioning, and in particular relates to a GNSS full-band adaptive pseudo-range single-point positioning algorithm. Background Art

[0002] With the comprehensive development of satellite navigation systems, the number of visible satellites has increased, and the satellite signals received in each frequency band are more abundant. Although the stability of single-point positioning can be improved, the problem of how to choose the optimal positioning solution is still faced. In order to ensure that during real-time positioning and solution, the satellite receiver can use the received pseudo-range signal to avoid the disadvantages of traditional fixed-frequency or fixed-frequency combined pseudo-range single-point positioning algorithms that cannot fully utilize the observation value when facing signal loss, resulting in a decrease in positioning performance and inability to perform positioning solution in severe cases, and can select the optimal pseudo-range observation value for positioning solution. While ensuring the positioning solution performance, it can make full use of the satellite signals received by the receiver and improve the robustness of the positioning solution. Therefore, it is urgent to propose an efficient and practical adaptive pseudo-range single-point positioning method. Summary of the invention

[0003] Purpose of the invention: The purpose of the present invention is to provide a GNSS full-band adaptive pseudo-range single-point positioning algorithm to solve the problem that the traditional single-point positioning algorithm with fixed frequency or fixed frequency combined pseudo-range cannot make full use of the observation value when facing signal loss, resulting in a decrease in positioning performance, and in severe cases, the positioning solution cannot be performed.

[0004] Technical solution: The GNSS full-band adaptive pseudo-range single-point positioning algorithm proposed in the present invention includes the following steps:

[0005] Step 1: Determine all types of pseudorange observations for each satellite navigation, and analyze and determine the accuracy of each type of pseudorange observation from three aspects: measurement noise, code pseudorange measurement accuracy, and positioning performance.

[0006] First of all, the types of satellite navigation pseudorange observations include: single-frequency pseudorange observations, dual-frequency ionospheric-free combined pseudorange observations, and triple-frequency ionospheric-free combined pseudorange observations.

[0007] 1) The single-frequency pseudorange observation model is:

[0008] P i =ρ+c(dt r -dt s )+T+I+TGD i (1)

[0009] Where P i is the pseudo-range measurement value of the satellite in the i-th frequency band; ρ is the geometric distance between the satellite and the receiver; dt r , and dt sare the receiver and satellite clock errors respectively; T and I are the tropospheric and ionospheric delays respectively, and TGD is the code group delay.

[0010] 2) The GPS dual-frequency ionospheric elimination combined pseudo-range observation model is:

[0011]

[0012] Where P IF is the pseudorange after dual-frequency ionospheric elimination combination, f i 、f j is the frequency of different frequency bands, P i , P j is the pseudorange observation value of different frequency bands, TGD i TGD j is the code group delay of different frequency bands.

[0013] 3) The BDS system dual-frequency ionospheric-free combined pseudo-range observation model is:

[0014]

[0015] Where P IF is the pseudorange after dual-frequency ionospheric elimination combination, f i 、f j is the frequency of different frequency bands, P3 is the pseudo-range observation value of B3 frequency band in BDS system, TGD i TGD j is the code group delay of different frequency bands.

[0016] 4) The three-frequency ionospheric elimination combined pseudo-range observation model is:

[0017] P IF123 =aρ i +bρ j +cρ k (4)

[0018] Where P IF123 is the three-frequency ionospheric elimination combined pseudorange, ρ i , j , k are the pseudoranges after code group delay correction in different frequency bands, a, b, c are the three-frequency ionospheric elimination combination coefficients, to ensure that the geometric distance meaning of the pseudorange observation value after combination remains unchanged, and the noise of the combined observation value is as small as possible. The three-frequency ionospheric elimination combination coefficients should meet the following conditions

[0019]

[0020] Furthermore, in order to solve the three-frequency deionospheric combination coefficient, the Lagrange multiplier method equation is constructed as follows:

[0021]

[0022] Furthermore, by taking the derivative of the variables and setting the derivative function to 0, the resulting system of equations is

[0023]

[0024] Furthermore, the three-frequency deionospheric combination coefficients a, b, and c are solved as follows:

[0025]

[0026] In the formula, f i 、f j 、f k The frequencies of different frequency bands.

[0027] Furthermore, the difference between the pseudo-range single-point positioning result in each epoch and the station in the east, north, and celestial directions is calculated, and the root mean square error at the 95% confidence level is calculated, that is,

[0028]

[0029] Where x, y, and z are the coordinate errors (m) in the east, north, and celestial directions, respectively, and n is the number of valid epochs in the frequency band.

[0030] Furthermore, based on the root mean square error obtained from the pseudorange single-point positioning results of the GNSS full-band, the priority of the full-band pseudorange observations is determined according to the accuracy of the pseudorange observations and the number of valid epochs of each frequency band.

[0031] Step 2: When performing real-time positioning and solving, the satellite receiver performs adaptive fusion positioning and solving according to the received pseudo-range signals. The specific method is as follows:

[0032] First, according to the pseudorange observations of all frequency bands and all channels received in the current epoch, for the pseudorange observations of different channels in the same frequency band, the pseudorange with the best quality is selected as the pseudorange observation of the current frequency band according to the priority of the channel;

[0033] Furthermore, for pseudorange observations in different frequency bands, the pseudorange with the best quality is selected as the pseudorange observation for participating in positioning solution according to the pre-determined single-frequency pseudorange and multi-frequency ionospheric elimination combined pseudorange priorities. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a flowchart of the process of the present invention;

[0035] Figure 2The position errors of the GPS satellite navigation L1 and the adaptive pseudo-range single-point positioning single-frequency pseudo-range single-point positioning in the east, north and sky directions in the embodiment of the present invention; DETAILED DESCRIPTION

[0036] The present invention will be further described below in conjunction with the accompanying drawings and examples.

[0037] The present invention proposes a GNSS full-band adaptive pseudo-range single-point positioning algorithm, which comprises the following steps:

[0038] Step 1): Determine all types of pseudorange observations of each satellite navigation, including single-frequency pseudorange observations, dual-frequency ionospheric elimination combined pseudorange observations, triple-frequency ionospheric elimination combined pseudorange observations, etc.

[0039] Specifically, taking the GPS satellite navigation system as an example, the specific steps for calculating the pseudorange observation are:

[0040] ①GPS hardware device delay correction model

[0041] Define K C12 The delay of the combined device without ionosphere satisfies the relationship:

[0042]

[0043] Where K1 and K2 are the code equipment delays on the L1 and L2 frequency bands, respectively; f1 and f2 are the frequencies of L1 and L2,

[0044] Define TGD as the code group delay, and it satisfies the relationship:

[0045]

[0046] In the formula, K 21 =K2-K1, K1, K2 are the code equipment delays on the L1, L2 frequency bands respectively, f1, f2 are the frequencies of L1, L2, and for the GPS system, TGD1, TGD2 parameters are included in the broadcast ephemeris.

[0047] Therefore, the model for correcting the pseudorange observation code equipment delay and the ionosphere-free combination equipment delay in the L1 and L2 frequency bands is:

[0048]

[0049] ②Single-frequency pseudorange observation model

[0050] P i =ρ+c(dt r -dt s )+T+I+TGD i (4)

[0051] Where Pi is the pseudo-range measurement value of the satellite in the i-th frequency band; ρ is the geometric distance between the satellite and the receiver; dt r , and dt s are the receiver and satellite clock errors respectively; T and I are the tropospheric and ionospheric delays respectively, and TGD is the code group delay, which is provided by the navigation file.

[0052] ③GPS dual-frequency ionospheric elimination combined pseudo-range observation model is:

[0053]

[0054] Where P IF is the pseudorange after dual-frequency ionospheric elimination combination, f i 、f j is the frequency of different frequency bands, P i , P j is the pseudorange observation value of different frequency bands, TGD i TGD j is the code group delay of different frequency bands.

[0055] In the GPS satellite navigation system, the satellite clock error is obtained based on the ionosphere-free combination L1 / L2. Therefore, for the ionosphere-free combination observation model using the L1 / L2 dual-frequency signal, no equipment delay correction is required.

[0056] ④ The three-frequency ionospheric elimination combined pseudo-range observation model is:

[0057] P IF123 =aρ i +bρ j +cρ k (6)

[0058] Where P IF123 is the three-frequency ionospheric elimination combined pseudorange, ρ i , j , k are the pseudoranges after code group delay correction in different frequency bands, a, b, c are the three-frequency ionospheric elimination combination coefficients, to ensure that the geometric distance meaning of the pseudorange observation value after combination remains unchanged, and the noise of the combined observation value is as small as possible. The three-frequency ionospheric elimination combination coefficients should meet the following conditions

[0059]

[0060] Therefore, in order to solve the three-frequency deionospheric combination coefficient, the Lagrange multiplier method equation is constructed

[0061]

[0062] Furthermore, the variables in the Lagrange multiplier method equation are differentiated and the derivative function is set to 0, and the three-frequency deionospheric combination coefficients a, b, and c are obtained respectively.

[0063]

[0064] In the formula, f i 、f j 、f k The frequencies of different frequency bands.

[0065] Step 2): Determine the priority of pseudo-range observations of each satellite navigation system in full frequency band.

[0066] Specifically, the method for determining the priority of pseudorange observations in all frequency bands of each satellite navigation system is as follows: first, by setting all types of pseudorange observations in the full frequency band, the positioning results of all frequency bands and frequency band combinations are solved; then, based on the reference coordinates, the root mean square errors in the east, north, and sky directions at a 95% confidence level are calculated; finally, based on the root mean square errors of all frequency bands and frequency band combinations and the number of valid epochs, the priority of the pseudorange observations is determined.

[0067] Step 3): According to the pseudo-range observations of all frequency bands and all channels received in the current epoch, an adaptive fusion positioning solution is performed based on the pre-determined priority.

[0068] Specifically, the following criteria are used to obtain the pseudorange observation with the best quality.

[0069] Criterion 1: For pseudorange observations of different channels in the same frequency band, the pseudorange with the best quality is selected as the pseudorange observation of the current frequency band according to the priority of the channel;

[0070] Criterion 2: For pseudorange observations in different frequency bands, the pseudorange with the best quality is selected as the pseudorange observation for positioning solution based on the pre-determined single-frequency pseudorange and multi-frequency ionospheric elimination combined pseudorange priority.

[0071] The embodiment of the present invention provides a set of test results of GPS full-band adaptive pseudo-range single-point positioning algorithm, and two schemes are used to perform static single-point positioning solution:

[0072] Solution 1: Traditional single point positioning algorithm with fixed frequency or fixed frequency combined pseudorange;

[0073] Solution 2: GNSS full-band adaptive pseudo-range single-point positioning algorithm;

[0074] The 24-hour observation data provided by the wuh2 observatory on September 1, 2024 is used. The single-point positioning solution is performed using Matlab software, and the relevant parameters are shown in the following table.

[0075] Table 1 Pseudorange single point positioning parameter settings

[0076]

[0077] Table 2 Results of traditional fixed frequency or fixed frequency combination distance observation

[0078]

[0079]

[0080] From the statistical results in Table 2, it can be seen that the positioning result error calculated by the GPS satellite navigation system using the L1 / L5 dual-frequency signal combination is the smallest, followed by the L1 / L5 dual-frequency signal combination, and then the L1 single-frequency signal. The largest error is the L5 single-frequency signal. Therefore, the priority of the pseudo-range observation of the GPS full-band adaptive pseudo-range single-point positioning algorithm is determined, so that the pseudo-range observation with the highest priority is obtained according to the pseudo-range signal received by the satellite receiver and the priority of the pseudo-range observation determined in the full-band case for positioning and solving the results as shown in Table 3.

[0081] Table 3 Results of GPS full-band adaptive pseudo-range single point positioning

[0082]

[0083] From the statistical results, it can be seen that the full-band adaptive pseudo-range single-point positioning algorithm uses a higher number of satellites than the traditional fixed-frequency band or fixed-frequency band combination when performing positioning solutions in each epoch on average.

[0084] The advantages of this method are: the method obtains the highest priority pseudo-range observation for positioning and solving according to the priority of the pseudo-range signal received by the satellite receiver and the pseudo-range observation determined in the full-band case, avoiding the disadvantages of the single-point positioning algorithm of the traditional fixed frequency or fixed frequency combination pseudo-range that cannot make full use of the observation when facing signal loss, resulting in a decline in positioning performance, and in severe cases, the inability to perform positioning and solving. At the same time, from the results of positioning and solving, the full-band adaptive pseudo-range single-point positioning results are better than the vast majority of single-point positioning algorithms of fixed frequency or fixed frequency combination pseudo-range, and the full-band adaptive pseudo-range single-point positioning algorithm uses more satellites than the traditional fixed frequency band or fixed frequency band combination when performing positioning and solving in each epoch.

[0085] The present invention is applicable to the field of GNSS positioning. The above is only a specific implementation of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A GNSS full-band adaptive pseudo-range single-point positioning algorithm, characterized in that The algorithm obtains the highest priority pseudorange observation for positioning solution based on the pseudorange signal received by the satellite receiver and the priority of the pseudorange observation determined in the full frequency band.

2. The GNSS full-band adaptive pseudo-range single-point positioning algorithm according to claim 1, characterized in that: The method for determining the priority of pseudorange observations in all frequency bands of each satellite navigation system is as follows: First, determine all types of pseudorange observations of each satellite navigation, including single-frequency pseudorange observations, dual-frequency ionospheric elimination combined pseudorange observations, and triple-frequency ionospheric elimination combined pseudorange observations. The measurement model of each observation is: 1) The single-frequency pseudorange observation model is P i =ρ+c(dt r -dt s )+T+I+TGD i (1) Where P i is the pseudo-range measurement value of the satellite in the i-th frequency band; ρ is the geometric distance between the satellite and the receiver; dt r and dt s are the receiver and satellite clock errors respectively; T and I are the tropospheric and ionospheric delays respectively, and TGD is the code group delay. 2) The GPS system dual-frequency ionospheric combined pseudo-range observation model is: Where P IF is the pseudorange after dual-frequency ionospheric elimination combination, f i 、f j is the frequency of different frequency bands, P i , P j is the pseudorange observation value of different frequency bands, TGD i TGD j is the code group delay of different frequency bands. 3) The BDS system dual-frequency ionospheric-free combined pseudo-range observation model is: Where P IF is the pseudorange after dual-frequency ionospheric elimination combination, f i 、f j is the frequency of different frequency bands, P3 is the pseudo-range observation value of B3 frequency band in BDS system, TGD i TGD j is the code group delay of different frequency bands. 4) The three-frequency ionospheric elimination combined pseudo-range observation model is: Where P IF123 is the three-frequency ionospheric elimination combined pseudorange, f i 、f j 、f k is the frequency of different frequency bands, ρ i , j , k They are the pseudoranges after code group delay correction in different frequency bands. Then, the accuracy of each type of pseudorange observation is analyzed and determined from three aspects: measurement noise, code pseudorange measurement accuracy and positioning performance.

3. The GNSS full-band adaptive pseudo-range single-point positioning algorithm according to claim 1, characterized in that: When performing real-time positioning solution, the specific method for the satellite receiver to perform adaptive fusion positioning solution based on the received pseudorange signals is as follows: based on the pseudorange observations of all frequency bands and all channels received in the current epoch, the pseudorange observations with the best quality are obtained based on a pre-determined priority.

4. The GNSS full-band adaptive pseudo-range single-point positioning algorithm as claimed in claim 3, characterized in that: The criteria for obtaining the best quality pseudorange observations are: Criterion 1: For pseudorange observations of different channels in the same frequency band, the pseudorange with the best quality is selected as the pseudorange observation of the current frequency band according to the priority of the channel; Criterion 2: For pseudorange observations in different frequency bands, the pseudorange with the best quality is selected as the pseudorange observation for positioning solution based on the pre-determined single-frequency pseudorange and multi-frequency ionospheric elimination combined pseudorange priority.

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