PPP-rtk-based prior hura value accuracy determination method and system

Abstract

The application relates to the technical field of navigation positioning, and discloses a prior HURA value accuracy determination method based on PPP-RTK, which is characterized in that: long-term PPP-RTK orbit and clock correction data are used to obtain post HURA; the prior HURA value is compared with the post HURA value, the accuracy of the prior HURA value is determined, and the prior HURA value is corrected. The application further discloses a prior HURA value accuracy determination system based on PPP-RTK. The accuracy of the prior HURA value can be effectively determined, and the real-time HURA value broadcast by PPP-RTK can be adjusted.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of navigation positioning, and in particular to a prior HURA value accuracy determination method and system for PPP-RTK. BACKGROUND

[0002] In the prior art, the signal-in-space range error (SISRE) describes the projection of satellite broadcast ephemeris error and clock error parameter error in the average user station direction of the user, and is a key factor affecting the accuracy of user positioning and timing. In order to describe the SISRE, the user ranging accuracy (URA) provides a conservative estimate of the unknown size of the SISRE, and the size of the URA also represents the accuracy of the space signal. The URA will be broadcast in the navigation message. Even if the URA is available in the navigation information, it must also be verified or adjusted by the navigation service provider before being provided to the user. This verification is generally done by comparing the accurately calculated post-URA value with the prior URA value in the navigation ephemeris to be verified to see if they are consistent. If the difference is too large, the prior URA calculation method needs to be adjusted.

[0003] There are already many methods for verifying whether the URA in the broadcast ephemeris is available. The results of the comparison between URA and the method set by the author in the paper "Algorithm Design and Experimental Analysis of Space Signal Accuracy" show that the URA parameter in the broadcast ephemeris of Beidou cannot accurately reflect the accuracy of the space signal, and the accuracy of the space signal of different satellites differs greatly. The paper "BDS Space Signal Abnormal Real-Time Detection and Exclusion Method" proposes a carrier phase smoothing pseudorange algorithm based on Kalman filtering, and establishes a real-time estimation method for BDS space signal user ranging error based on the statistical characteristics of BDS system URA, thereby detecting and excluding BDS space signal abnormalities in real time. The results show that the estimation accuracy of the proposed method for Beidou system URA is 1.15m. The paper "Characteristics of BDS Signal-in-Space User Ranging Errors and Their Effect on Advanced Receiver Autonomous Integrity Monitoring Performance" compares the broadcast ephemeris and precise ephemeris from 2013 to 2017, obtains the corresponding SISRE, and calculates the URA using the SISRE. The results show that a URA of 2m cannot fully meet the system performance during the evaluation period, but a URA with a threshold of 2.4m is more suitable for users.

[0004] The above methods all verify and analyze URA in broadcast ephemeris after the event, and the technology PPP-RTK, which is relatively hot in recent years, also needs to provide high-precision URA (High-precision URA, HURA). Unlike broadcast ephemeris, PPP-RTK corrects the satellite position and clock error calculated by broadcast ephemeris by providing orbit and clock error correction, which greatly improves the precision of high-precision SISRE mainly affected by orbit and clock error compared with the SISRE calculated by broadcast ephemeris. As the HURA precision representing high-precision SISRE is naturally higher, it also means that its value will be smaller. Therefore, the HURA provided by PPP-RTK also needs to design a corresponding method to verify the effectiveness of the prior value of HURA and the normal range of its value. The verification result can be used by the navigation service provider as the basis for adjusting the prior HURA calculation strategy. But no one designs a method to verify the HURA of the PPP-RTK server after the event and adjust the data according to the actual situation. SUMMARY

[0005] Based on the above situation, the application provides a prior HURA value accuracy determination method based on PPP-RTK. The method obtains and statistics the prior HURA value in unit time, obtains the post HURA value by obtaining the PPP-RTK orbit, clock correction data, navigation ephemeris, IGS precise ephemeris and clock error data of the current satellite, compares the prior HURA value with the post HURA value, and finally judges the accuracy of the prior HURA value. The long-term PPP-RTK orbit and clock correction data are used to calculate the post HURA. The post HURA is used as a reference quantity to judge the good and bad of the prior HURA information of PPP-RTK and the fault condition, and to correct the prior HURA.

[0006] The application discloses a prior HURA value accuracy determination method based on PPP-RTK, acquires a prior HURA value generated in real time by PPP-RTK, PPP-RTK orbit correction data, PPP-RTK clock correction data, navigation ephemeris, IGS precise ephemeris and IGS precise clock data; calculates a current satellite position and a first clock difference according to the navigation ephemeris; generates high-precision orbit coordinates and clock information according to the current satellite position, the first clock difference, the PPP-RTK orbit correction data and the PPP-RTK clock correction data; matches the high-precision orbit coordinates and clock information with the IGS precise ephemeris and IGS precise clock data to obtain high-precision orbit errors and high-precision clock differences; obtains high-precision space signal errors through the high-precision orbit errors and high-precision clock differences; forms a high-precision space signal ranging error sequence by statistically counting high-precision space signal ranging errors in a unit time, generates a posteriori HURA values by performing error envelope generation on high-precision space signal ranging error sequence data in the unit time; compares the prior HURA value with the a posteriori HURA value to determine the accuracy of the prior HURA value.

[0007] The PPP-RTK orbit correction data, the PPP-RTK clock correction data, the navigation ephemeris, the IGS precise ephemeris and the IGS precise clock data can be preprocessed before use.

[0008] The application further discloses a prior HURA value accuracy determination system based on PPP-RTK, comprising a satellite data acquisition module, a data processing module and a prior HURA value accuracy determination module; the modules are connected in signal; the satellite data acquisition module is used to acquire a prior HURA value generated in real time by PPP-RTK, PPP-RTK orbit correction data, PPP-RTK clock correction data, navigation ephemeris, IGS precise ephemeris and IGS precise clock data; the data processing module is used to calculate a current satellite position and a first clock difference according to the navigation ephemeris; generate high-precision orbit coordinates and clock information according to the current satellite position, the first clock difference, the PPP-RTK orbit correction data and the PPP-RTK clock correction data; match the high-precision orbit coordinates and clock information with the IGS precise ephemeris and IGS precise clock data to obtain high-precision orbit errors and high-precision clock differences; the prior HURA value accuracy determination module obtains high-precision space signal errors through the high-precision orbit errors and high-precision clock differences; forms a high-precision space signal ranging error sequence by statistically counting all high-precision space signal ranging errors in a unit time, generates a posteriori HURA values by performing error envelope generation on high-precision space signal ranging error sequence data in the unit time; compares the prior HURA value with the a posteriori HURA value to determine the accuracy of the prior HURA value.

[0009] Some technical effects disclosed by the application are as follows: in the case that the HURA value is affected by the PPP-RTK orbit correction number, the PPP-RTK clock correction number, the satellite ephemeris and the calculation method thereof, and the abnormal situation of the HURA value is prone to occur, the application can effectively determine the accuracy of the prior HURA value and adjust the real-time HURA value broadcast by the PPP-RTK, and the obtained post-factum integrity information HURA is more accurate than the prior integrity information HURA. BRIEF DESCRIPTION OF DRAWINGS

[0010] In order to better understand the technical solutions of the present disclosure, reference can be made to the following drawings which are used to assist in explaining the prior art or embodiments. These drawings will selectively show the products or methods involved in the prior art or part of the embodiments of the present disclosure. The basic information of these drawings is as follows:

[0011] Figure 1 is a flowchart of an embodiment of a prior HURA value accuracy determination method based on PPP-RTK of the present application.

[0012] Figure 2 is a structural schematic diagram of an embodiment of a prior HURA value accuracy determination system based on PPP-RTK of the present application. DETAILED DESCRIPTION

[0013] The technical means or technical effects involved in the present disclosure will be further described below. Obviously, the provided embodiments are only part of the embodiments of the present disclosure, but not all. Based on the embodiments in the present disclosure and the explicit or implicit indications of the drawings, all other embodiments that can be obtained by those skilled in the art without creative labor shall be within the scope of protection of the present disclosure.

[0014] As shown in Figure 1 , the method in the embodiment includes the following steps:

[0015] S1, obtaining the prior HURA value generated by the PPP-RTK in real time, the PPP-RTK orbit correction data, the PPP-RTK clock correction data, the navigation ephemeris, the IGS precise ephemeris and the IGS precise clock data;

[0016] The corresponding satellite data in a unit of time is acquired, including receiving the prior HURA value generated by PPP-RTK in real time, the PPP-RTK orbit correction data, the PPP-RTK clock correction data, the navigation ephemeris, the IGS precise ephemeris and the IGS precise clock data. During the data receiving process, the received signal may be disconnected due to satellite factors, receiver hardware failure, poor receiving environment and the like. Each year, 135000 navigation ephemeris and various correction data are destroyed by data recording errors. A small part of these destroyed navigation ephemeris files has defects such as loss, repetition, inconsistency and errors. These data recording errors are mainly caused by accidental bad receiver provided data and various hardware / software errors, so these data need to be preprocessed for a long time. The preprocessing method is mainly to clean and screen the data by using a data cleaning algorithm. If one of the following conditions is met, the PPP-RTK orbit correction data, the navigation ephemeris, the IGS precise ephemeris and the IGS precise clock data in the corresponding time period are excluded. The purpose is to exclude invalid data and retain effective data that may have true abnormal spatial signals: a. No orbit and clock correction data is received; b. The precise ephemeris / clock is lost or set to an invalid precise ephemeris / clock value, such as “999, 999.9999” or “NAN”; c. Not within 2 hours of broadcast ephemeris (GPS is 4 hours); d. The integrity status identifier is not zero, or the URA is greater than 48m; e. The navigation message is unhealthy, that is, the health status identifier is “1”.

[0017] S2, calculating the current satellite position and the first clock difference according to the navigation ephemeris; generating high-precision orbit coordinates and clock information according to the current satellite position, the first clock difference, the PPP-RTK orbit correction data and the PPP-RTK clock correction data; and matching the high-precision orbit coordinates and the clock information with the IGS precise ephemeris and the IGS precise clock data to obtain high-precision orbit error and high-precision clock difference;

[0018] calculating the current satellite position and the first clock difference by using the effective navigation ephemeris data obtained by S1; obtaining high-precision orbit coordinates and clock information by using a PPP-RTK orbit clock repair algorithm with the current satellite position, the first clock difference, the PPP-RTK orbit correction data and the PPP-RTK clock correction data; and matching the calculated high-precision orbit coordinates and clock information with the IGS post-precise ephemeris as the orbit and clock true value reference quantity in time and taking the difference to obtain high-precision orbit error and high-precision clock difference by using a GNSS satellite orbit high-precision real-time interpolation algorithm;

[0019] The high-precision orbit error and high-precision clock error are detected and excluded by setting fixed orbit radial error, tangential error, normal error and clock error abnormal threshold according to the orbit type. By using statistical method, the normal distribution is generally met by the error sequence without abnormality. If the high-precision orbit error and high-precision clock error sequence after elimination meets the normal distribution, the high-precision orbit error and high-precision clock error under the condition of no fault are obtained. The reason for the abnormal detection and elimination here is that the broadcast fault of PPP-RTK may exist, so that the orbit and clock calculated by the wrong correction broadcast ephemeris are abnormally large, and the abnormal orbit clock error will cause the URA value to change after verification.

[0020] S3, high-precision space signal error is obtained by the high-precision orbit error and high-precision clock error; high-precision space signal ranging error sequence is formed by all high-precision space signal ranging errors in a unit time, and error envelope is generated for the high-precision space signal ranging error sequence data in a unit time to obtain post-HURA value; the accuracy of the prior HURA value is judged by comparing the prior HURA value with the post-HURA value.

[0021] The high-precision orbit error, high-precision worst-case space signal error and high-precision space signal error under the condition of no fault are obtained.

[0022] Because the observation geometry of different orbits of different systems is different, the calculation models of the space signal errors of the three orbits are different, and the calculation models are as follows:

[0023]

[0024]

[0025] Wherein, SISURE MEO represents the space signal error of the satellite MEO orbit type; SISURE IGSO / GEO represents the space signal error of the satellite IGSO and GEO orbit type; R represents radial error; A represents tangential error; and C represents normal error. R, A and C are three directions of high-precision orbit error, and T represents high-precision clock error. The radial error, tangential error and normal error are projected to the satellite-user connecting line direction respectively to obtain high-precision space signal user ranging error. Here, the user position is a, the satellite position is b, is the angle between the satellite-user connecting line and the ground. The formula for projecting the satellite to the user line-of-sight direction is:

[0026] After obtaining the high-precision space signal error, it is projected to the user's line-of-sight direction to obtain the worst-case high-precision space signal ranging error, and a high-precision space signal ranging error sequence is formed by counting all high-precision space signal ranging errors in a unit time. The high-precision space signal ranging error sequence is subjected to error envelope modeling, and the high-precision space signal ranging error sequence data in a unit time is subjected to error envelope. According to the distribution sequence of the high-precision space signal ranging error after envelope in a unit time, a cumulative distribution function (CDF) curve is generated, and the value of the normal distribution is found , wherein is 0.68. The upper limit value of the core error of the normal distribution, that is, the post-HURA value of the PPP-RTK; the post-HURA value obtained is used as a reference to compare with the prior HURA value to obtain the posterior residual (that is, the difference obtained by subtracting the post-HURA value from the prior HURA value), and compared with a fixed threshold to judge the accuracy of the prior HURA. When the posterior residual obtained is greater than the fixed threshold, the prior HURA is compensated by 80% residual through the posterior residual; here, the 80% residual compensation is to add the posterior residual*80% to the prior HURA to compensate the accuracy of the prior HURA. When the posterior residual obtained is not greater than the fixed threshold, it is considered that the prior HURA is correct information, and no compensation is made to achieve the purpose of dynamically adjusting the prior HURA. In the stage when the PPP-RTK integrity service product is not mature, the prior integrity HURA information broadcast in real time will have many unstable and incorrect broadcast phenomena, which also shows that the prior HURA value and its calculation strategy need to be continuously improved. The method uses long-term PPP-RTK orbit and clock correction data to obtain the post-accurate HURA. The post-accurate HURA is used as a reference to judge the good and bad of the prior integrity HURA information of the PPP-RTK, and the prior HURA value and its calculation strategy can be adjusted according to the judgment result until the prior HURA and the post-HURA value are consistent.

[0027] As Figure 2As shown, another embodiment of the application is a priori HURA value accuracy determination system based on PPP-RTK: comprising a satellite data acquisition module, a data processing module, and a priori HURA value accuracy determination module; the signals of each module are connected; the satellite data acquisition module is used to acquire the priori HURA value generated by PPP-RTK in real time, the PPP-RTK orbit correction data, the PPP-RTK clock correction data, the navigation ephemeris, the IGS precise ephemeris, and the IGS precise clock data; the data processing module is used to calculate the current satellite position and the first clock difference according to the navigation ephemeris; generate high-precision orbit coordinates and clock information according to the current satellite position, the first clock difference, the PPP-RTK orbit correction data, and the PPP-RTK clock correction data; match the high-precision orbit coordinates and the clock information with the IGS precise ephemeris and the IGS precise clock data to obtain high-precision orbit error and high-precision clock difference; the priori HURA value accuracy determination module obtains high-precision space signal error through the high-precision orbit error and the high-precision clock difference; form a high-precision space signal ranging error sequence by statistically all high-precision space signal ranging errors in a unit time, generate a post HURA value by error envelope of high-precision space signal ranging error sequence data in a unit time; compare the priori HURA value with the post HURA value to determine the accuracy of the priori HURA value.

[0028] The use content and conditions of an embodiment of a priori HURA value accuracy determination system based on PPP-RTK are similar to those of the method embodiment of the application, and will not be described in detail here.

[0029] As can be understood by those skilled in the art, all or part of the steps in the embodiments can be instructed by a computer program to relevant hardware, and the program can be stored in a computer readable medium, which can include a flash disk, a mobile hard disk, a read-only memory, a random access memory, a magnetic disk or an optical disk, and various media that can store program codes. In one embodiment, the present disclosure proposes a computer readable medium, which stores a computer program, and the computer program is loaded and executed by a processing module to implement the priori HURA value accuracy determination method based on PPP-RTK.

[0030] Within the scope of the knowledge and ability of those skilled in the art, the various embodiments or technical features mentioned herein can be combined with each other without conflict to form other optional embodiments, and these limited number of optional embodiments formed by limited number of technical features without being listed one by one are still within the technical scope disclosed by the present disclosure, and can be understood or inferred by those skilled in the art in combination with the drawings and the above.

[0031] In addition, the description of most embodiments is based on different emphases, and the parts not described in detail can be understood by referring to the contents of the prior art or other related descriptions herein.

[0032] It is to be emphasized again that the above-mentioned embodiments are typical and preferred embodiments of the present disclosure, which are only used for detailed description and explanation of the technical solutions of the present disclosure, so as to facilitate the understanding of the readers, and do not limit the protection scope or application of the present disclosure. Any modifications, equivalent replacements, improvements, etc. obtained within the spirit and principles of the present disclosure should be covered within the protection scope of the present disclosure.

Claims

1. A method for determining accuracy of a prior HURA value based on PPP-RTK, characterized in that: The prior HURA value generated in real time by PPP-RTK, PPP-RTK orbit correction data, PPP-RTK clock correction data, navigation ephemeris, IGS precise ephemeris and IGS precise clock data are acquired; the current satellite position and the first clock difference are calculated according to the navigation ephemeris; high-precision orbit coordinates and clock information are generated according to the current satellite position, the first clock difference, the PPP-RTK orbit correction data and the PPP-RTK clock correction data; high-precision orbit errors and high-precision clock differences are obtained by matching the high-precision orbit coordinates and the clock information with the IGS precise ephemeris and the IGS precise clock data; high-precision spatial signal ranging errors are obtained by the high-precision orbit errors and the high-precision clock differences; a high-precision spatial signal ranging error sequence is formed by the high-precision spatial signal ranging errors in a unit time, and a posteriori HURA value is generated by error envelope of the high-precision spatial signal ranging error sequence data in a unit time; the accuracy of the prior HURA value is judged by comparing the prior HURA value with the posteriori HURA value.

2. The a priori HURA value accuracy determination method of claim 1, wherein: The PPP-RTK orbit correction data, the PPP-RTK clock correction data, the navigation ephemeris, the IGS precise ephemeris and the IGS precise clock data can be preprocessed before use.

3. The a priori HURA value accuracy determination method of claim 1, wherein: The calculation method of the high-precision spatial signal error obtained by the high-precision orbit error and the high-precision clock difference is as follows: a calculation model is established by three orbit spatial signal errors, Where R represents the radial error, A represents the tangential error, and C represents the normal error; R, A and C are three directions of high-precision orbit error, and T represents high-precision clock difference; the radial error, the tangential error and the normal error are projected to the satellite-user connecting direction respectively to obtain high-precision spatial signal user ranging error.

4. The a priori HURA value accuracy determination method of claim 3, wherein: The error envelope generation post-HURA value of the high-precision space signal ranging error sequence data in unit time; Specifically, it includes: by establishing a single-sided error envelope model for the high-precision space signal ranging error sequence, the error envelope of the high-precision space signal ranging error sequence data in unit time is generated, and the cumulative distribution function curve is generated according to the distribution sequence of the high-precision space signal ranging error in unit time after envelope, and the total normal distribution value is the post-HURA value of PPP-RTK, wherein is 0.

68.

5. The method of claim 1-4, wherein: The posterior residual error is obtained by comparing the posteriori HURA value as a reference with the prior HURA value; when the posterior residual error is greater than a fixed threshold, the prior HURA is compensated by 80% residual error according to the posterior residual error.

6. A system for determining the accuracy of a prior HURA value based on PPP-RTK, characterized by: The satellite data acquisition module, the data processing module and the prior HURA value accuracy judgment module are included; the signals of each module are connected; the satellite data acquisition module is used to acquire the prior HURA value generated in real time by PPP-RTK, PPP-RTK orbit correction data, PPP-RTK clock correction data, navigation ephemeris, IGS precise ephemeris and IGS precise clock data; The data processing module is configured to calculate a current satellite position and a first clock error according to the navigation ephemeris, generate high-precision orbit coordinates and clock information according to the current satellite position, the first clock error, the PPP-RTK orbit correction data and the PPP-RTK clock correction data, match the high-precision orbit coordinates and the clock information with the IGS precise ephemeris and the IGS precise clock data to obtain high-precision orbit error and high-precision clock error, and obtain high-precision space signal error according to the high-precision orbit error and the high-precision clock error.

7. The a priori HURA value accuracy determination system of claim 6, wherein: The calculation method of the high-precision space signal error according to the high-precision orbit error and the high-precision clock error is as follows: a calculation model is established by using three orbit space signal errors, wherein R represents a radial error, A represents a tangential error, and C represents a normal error; R, A and C are three directions of the high-precision orbit error, and T represents the high-precision clock error; the radial error, the tangential error and the normal error are projected to a satellite-user connecting line direction respectively to obtain high-precision space signal user ranging error.

8. The a priori HURA value accuracy determination system of claim 7, wherein: The error envelope generation post-HURA value of the high-precision space signal ranging error sequence data in unit time; Specifically, it includes: by establishing a single error envelope model for the high-precision space signal ranging error sequence, the error envelope of the high-precision space signal ranging error sequence data in unit time is generated, the cumulative distribution function curve is generated according to the distribution sequence of the high-precision space signal ranging error in unit time after envelope, and the value of the total normal distribution is taken as the post-HURA value of PPP-RTK, wherein The value of the total normal distribution is 0.

68. The value of the total normal distribution is 0.

68.

9. A prior HURA value accuracy determination system according to any of claims 6-8, characterized in that: The posterior residual error is obtained by comparing the posterior HURA value with the prior HURA value as a reference; when the posterior residual error is greater than a fixed threshold, the prior HURA is compensated by 80% residual error according to the posterior residual error.

10. A computer readable medium having stored therein a computer program, the computer program comprising: The computer program is loaded and executed by the processing module to realize the prior HURA value accuracy determination method according to any one of claims 1-5.

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