A receiver autonomous integrity monitoring method based on generalized RDSS positioning

Abstract

The application provides a receiver autonomous integrity monitoring method based on generalized RDSS positioning, and relates to the field of satellite navigation applications.The method is used for the traditional autonomous integrity scene with more than 6 available satellites, and is based on receiver autonomous integrity monitoring to check and confirm the fault satellites monitored and identified by the autonomous integrity, so as to reduce the false alarm probability; for the autonomous integrity scene with less than 6 available satellites, the method is used for the generalized RDSS positioning in the form of available satellite combination to complete the pseudo-range positioning calculation of the available satellites, and the positioning result difference fitting is used to identify the fault satellites, so as to complete the implementation monitoring and identification of the receiver autonomous integrity. The method is not restricted by the number of visible satellites in space, the precision factor of the visible satellites and the fast or slow change of the fault satellites, and has good autonomous integrity monitoring effect for single satellite fault, multi-satellite fault and slow change satellite fault.

Description

Technical Field

[0001] This invention relates to the field of satellite navigation applications, and in particular to a receiver autonomous integrity monitoring method based on generalized RDSS positioning. Background Technology

[0002] Integrity refers to the ability of a satellite navigation system to promptly alert users when some satellites malfunction or their errors exceed certain limits, rendering the system unsuitable for navigation and positioning. Current integrity monitoring primarily focuses on two approaches: first, monitoring satellite navigation integrity based on external auxiliary systems or methods, including satellite-based and ground-based augmentation systems. This involves real-time monitoring and alarm broadcasting of the space-based satellite navigation system to monitor the integrity of the user-side receiver. Second, autonomous receiver integrity monitoring. This approach does not require external auxiliary information. The receiver utilizes redundant satellite observations for consistency checks, and uses statistical analysis of redundant satellite observations to separate faulty satellite observations, enabling autonomous monitoring of faulty satellites and timely warnings to users.

[0003] Traditional autonomous integrity monitoring is based on observation data from multiple satellite epochs received simultaneously. It uses snapshot statistics methods such as pseudorange comparison, least squares residual, and parity vector methods to identify and monitor faulty satellites. However, traditional autonomous integrity monitoring has significant limitations in terms of the number of observed satellites, satellite accuracy factors, the rate of change of faulty satellites, multiple satellite faults, and high false alarm rate, as detailed below:

[0004] 1. Traditional autonomous integrity monitoring methods have high requirements for the number of redundant satellite observations, requiring at least six independent satellites to perform autonomous integrity monitoring, and integrity alarms have a certain probability of false alarms and missed alarms.

[0005] 2. Traditional autonomous integrity monitoring methods have high requirements for the quality of redundant satellite observations. When the distribution accuracy factor of the observed satellites is poor, the alarm capability of autonomous integrity monitoring is reduced accordingly.

[0006] 3. Traditional autonomous integrity monitoring methods have certain limitations in identifying fault models. They can effectively monitor rapidly changing faults, but have a high probability of missing alarms when monitoring slowly changing faults.

[0007] With the launch and operation of the BeiDou-3 Global Navigation Satellite System, RDSS / RNSS dual-mode receivers based on the BeiDou system have become the mainstream in satellite navigation equipment. For these widely used BeiDou dual-mode receivers, the key to successful receiver integrity monitoring lies in fully utilizing the advantages of the RDSS / RNSS dual-mode positioning technology within the BeiDou system. This involves leveraging the receiver's equipment characteristics and the system's inherent design advantages, and designing relevant algorithms to achieve autonomous integrity monitoring without adding external auxiliary means. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the above-mentioned background technology and propose a receiver autonomous integrity monitoring method based on generalized RDSS positioning. This method utilizes the advantages of the generalized RDSS positioning technology of the BeiDou satellite navigation system and the receiver's existing dual-mode receiving and processing capabilities. Regardless of whether the number of available satellites is greater than 6, the integrity of the receiver can be monitored.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0010] A receiver autonomous integrity monitoring method based on generalized RDSS positioning includes the following steps:

[0011] (1) The receiver starts working, completes the acquisition, tracking and demodulation of signals from all visible satellites in space, receives and stores all observation history data of all available satellites that can participate in positioning, including satellite ephemeris, almanac, and pseudorange observations.

[0012] (2) Determine whether the number of available satellites is greater than 6. If the number of available satellites is greater than 6, then the faulty satellites are monitored and identified by calculating and accumulating the odd and even vectors, the faulty satellites are removed, the navigation and positioning solution is completed, and then the process proceeds to step 3 to continue monitoring and verifying the generalized RDSS of the faulty satellites. If the number of available satellites is less than 6, then the process proceeds to step 4.

[0013] (3) The pseudorange observations of the satellites identified as normal participating in the navigation and positioning calculation are packaged as the pseudorange observations of the RNSS for generalized RDSS positioning and sent to the ground processing center. The ground processing center performs three-sphere positioning calculation based on the pseudorange difference of the RNSS and the two-way ranging value of the RDSS to obtain the generalized RDSS positioning result of the normal satellite. The positioning calculation result of the receiver is cross-fitted with the generalized RDSS positioning result of the normal satellite. The cross-fitting result is compared with the positioning error threshold. If the deviation does not exceed the threshold, it indicates that the autonomous integrity monitoring result of the receiver is correct. The pseudorange observations of the satellites identified as faulty are used for generalized RDSS positioning. The positioning result is cross-fitted with the generalized RDSS positioning result of the normal satellite. If the cross-fitting result does not exceed the threshold, it indicates that the faulty satellite is incorrectly identified and there is a false alarm. If the cross-fitting result exceeds the threshold, it indicates that the current satellite is a faulty satellite.

[0014] Complete autonomous integrity monitoring and verification when there are more than 6 satellites;

[0015] (4) Pack the pseudorange observations of any two available RNSS satellites as pseudorange observations for generalized RDSS positioning and send them to the ground processing center. The ground processing center performs three-sphere positioning calculation based on the pseudorange difference of RNSS and the two-way ranging value of RDSS to complete the generalized RDSS positioning. Then, the pseudoranges of other available RNSS satellites are rotated for generalized RDSS positioning until all available RNSS satellites have completed the generalized RDSS positioning calculation by combining pairs of satellites.

[0016] All positioning results are cross-fitted. If the cross-fitting result does not exceed the threshold, it means that all satellites are normal. If the cross-fitting result exceeds the threshold, select the RNSS satellites whose cross-fitting results of generalized RDSS positioning exceed the threshold and determine that the satellite is a faulty satellite.

[0017] Complete autonomous integrity monitoring when the number of available satellites is less than 6.

[0018] Compared with traditional autonomous integrity monitoring methods in the prior art, the present invention has the following advantages:

[0019] 1. The autonomous integrity monitoring method of the present invention fully utilizes the design advantages of the generalized RDSS positioning technology system of the Beidou satellite navigation system to achieve integrity monitoring. The monitoring method is robust and reliable, and is not constrained by factors such as the number of visible satellites in space, satellite accuracy factor, and satellite failure mode. It has the advantages of high monitoring accuracy, strong alarm real-time performance, and low false alarm probability.

[0020] 2. The autonomous integrity monitoring method of the present invention is based on the generalized RDSS positioning technology of the Beidou navigation system. It adopts a reliable two-way active positioning mode to monitor and verify the integrity of visible satellites in space. It is safe, reliable and robust. It has good monitoring effect on fault modes such as single satellite fault, multi-satellite fault, and slow-change satellite fault. It has the advantages of high monitoring accuracy and wide application scenario coverage.

[0021] 3. This invention does not require external supporting environments such as satellite-based augmentation systems or ground-based augmentation systems, nor does it require additional hardware platform configuration or external auxiliary information support. It can achieve autonomous integrity monitoring of the bidirectional active positioning dimension by simply adding a pseudorange verification mode of available satellites based on generalized RDSS positioning to the receiver baseband processing algorithm. It has low environmental dependence, simple engineering implementation, strong updability, and is easy to apply and promote.

[0022] 4. Based on the generalized RDSS positioning technology provided by the BeiDou system, this invention opens up a more robust and secure autonomous integrity monitoring method on the basis of traditional autonomous integrity monitoring. It is applicable to all signal systems, including public and authorized signals, and is suitable for ordinary BeiDou dual-mode receivers, command-type BeiDou user terminals, timing-type BeiDou dual-mode user terminals, array anti-interference type BeiDou dual-mode user terminals, etc. It is simple, efficient, safe, reliable, and has a wide range of applications, and has good promotion and application value. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of receiver autonomous integrity monitoring based on generalized RDSS positioning;

[0024] Figure 2 This is a flowchart of the receiver autonomous integrity monitoring process based on generalized RDSS positioning. Detailed Implementation

[0025] An autonomous integrity monitoring method for receivers based on generalized RDSS positioning is proposed. This method first initiates the receiver's normal operation, acquiring, tracking, and demodulating visible satellite signals, and receiving all observational data from currently visible satellites, including ephemeris, almanac, pseudorange, and other information and observations. The receiver then enters the autonomous integrity monitoring process according to standard operating mode. First, it determines whether the number of available satellites is greater than six. If the number is greater than six, it enters the traditional autonomous integrity monitoring process, using a standard autonomous integrity monitoring parity vector algorithm to perform calculations and accumulations, thereby monitoring and identifying faulty satellites. Finally, faulty satellites are removed from the navigation and positioning calculations. Simultaneously, the pseudoranges of observed satellites identified as normal are packaged as RNSS pseudoranges for generalized RDSS positioning and sent to the ground processing center. Generalized RDSS positioning is used for positioning calculation and verification. The ground processing center performs three-sphere positioning calculation based on the RNSS pseudorange difference and the two-way ranging value of RDSS. The receiver's positioning calculation result is cross-fitted with the generalized RDSS positioning result of normal satellites. The cross-fitted result is compared with a positioning error threshold. If the deviation does not exceed the threshold, the receiver's autonomous integrity monitoring result is correct. Then, the pseudoranges of observed satellites identified as faulty are subjected to generalized RDSS positioning in the same manner. The positioning result is cross-fitted with the generalized RDSS positioning result of normal satellites. If the cross-fitted result does not exceed the threshold, it indicates that the faulty satellite was incorrectly identified, resulting in a false alarm. If it exceeds the threshold, it indicates that the current satellite is faulty. This completes the autonomous integrity monitoring and verification in the mode with more than 6 available satellites. If the number of available satellites is less than 6, the receiver cannot enter the traditional autonomous integrity monitoring process and directly switches to the generalized RDSS autonomous integrity monitoring process. The pseudoranges of any two available RNSS satellites are packaged as the RNSS pseudoranges for generalized RDSS positioning and sent to the ground processing center. The ground processing center performs three-sphere positioning calculation based on the pseudorange difference between the RNSS satellites and the two-way ranging value of the RDSS satellites. It then rotates the pseudoranges of other available RNSS satellites for generalized RDSS positioning until all pairs of RNSS satellites have completed the generalized RDSS positioning calculation. The positioning results are then cross-fitted. If the cross-fitting result does not exceed the threshold, it indicates that all satellites are normal. If the cross-fitting result exceeds the threshold, the RNSS satellite whose cross-fitting result for generalized RDSS positioning exceeds the threshold is selected, and the satellite is determined to be a faulty satellite, thus completing the autonomous integrity monitoring.

[0026] Specifically, the steps include the following:

[0027] (1) The receiver starts working in normal working mode, completes the acquisition, tracking and demodulation of all visible satellite signals in space, and receives all observation data of the currently visible satellites, including satellite ephemeris, almanac, pseudorange and other observation data.

[0028] (2) After receiving the historical data of the space-visible satellite, the receiver enters the autonomous integrity monitoring process in normal mode. First, it determines whether the number of available satellites is greater than 6. If the number of satellites is greater than 6, it enters the traditional autonomous integrity monitoring process. Through statistical processing such as the calculation and accumulation of odd and even vectors, it completes the monitoring and identification of faulty satellites, removes faulty satellites, completes navigation and positioning calculation, and then moves to the next step to continue the monitoring and verification of the generalized RDSS of faulty satellites.

[0029] (3) The pseudorange observations of the satellites identified as normal participating in the navigation and positioning calculation are packaged as the pseudorange observations of the RNSS for generalized RDSS positioning and sent to the ground processing center. The ground processing center performs three-sphere positioning calculation based on the pseudorange difference of the RNSS and the two-way ranging value of the RDSS to obtain the generalized RDSS positioning result of the normal satellite. The positioning calculation result of the receiver is cross-fitted with the generalized RDSS positioning result of the normal satellite. The cross-fitting result is compared with the positioning error threshold. If the deviation does not exceed the threshold, it indicates that the autonomous integrity monitoring result of the receiver is correct. Then, the pseudorange observations of the satellites identified as faulty are generalized RDSS positioned in the same way as above. The positioning result is cross-fitted with the generalized RDSS positioning result of the normal satellite. If the cross-fitting result does not exceed the threshold, it indicates that the faulty satellite is incorrectly identified and there is a false alarm. If it exceeds the threshold, it indicates that the current satellite is a faulty satellite. The autonomous integrity monitoring and verification is completed when the number of satellites is greater than 6. If the number of usable satellites is less than 6, the monitoring and processing are directly transferred to the generalized RDSS autonomous integrity monitoring process.

[0030] (4) The pseudorange observations of any two available RNSS satellites are packaged as pseudorange observations for generalized RDSS positioning and sent to the ground processing center. The ground processing center performs three-sphere positioning calculation based on the pseudorange difference of RNSS and the two-way ranging value of RDSS to complete the generalized RDSS positioning. The pseudoranges of other available RNSS satellites are rotated for generalized RDSS positioning until all available RNSS satellites have completed the pairwise combination of generalized RDSS positioning calculations. All positioning calculation results are cross-fitted. If the cross-fitting result does not exceed the threshold, it indicates that all are normal satellites; if the cross-fitting result exceeds the threshold, the RNSS satellite corresponding to the cross-fitting result of the generalized RDSS positioning calculation that exceeds the threshold is selected, and the satellite is determined to be a faulty satellite; autonomous integrity monitoring is completed when the number of available satellites is less than 6, and finally autonomous integrity monitoring, identification, and alarm output are realized.

[0031] Based on the above steps, the real-time online monitoring of the receiver's autonomous integrity based on generalized RDSS positioning is completed.

[0032] In step (1), the receiver starts working in normal working mode, completes the acquisition, tracking and demodulation of space visible satellite signals, and receives and stores all observation data of all visible satellites that can participate in positioning, including information and observations such as the ephemeris, almanac, pseudorange and other data of visible satellites.

[0033] In step (2), the visible satellite information and observations received in step (1) are evaluated. If the number of available satellites is greater than 6, the traditional autonomous integrity monitoring process can be started first to perform autonomous integrity monitoring. The entire traditional autonomous integrity process includes processing steps such as the calculation and accumulation of odd and even vectors, and finally outputs the monitoring and identification results of the faulty satellites. Then, it is transferred to the generalized RDSS verification and monitoring step of the faulty satellites.

[0034] In step (3), the pseudorange of the normal satellites participating in the navigation and positioning calculation in step (2) is packaged as the pseudorange observation of the RNSS for generalized RDSS positioning and sent to the ground processing center. The ground processing center performs three-sphere positioning calculation based on the pseudorange difference of the RNSS and the two-way ranging value of the RDSS to obtain the generalized RDSS positioning result of the normal satellite. The positioning calculation result of the receiver is cross-fitted with the generalized RDSS positioning result of the normal satellite. The cross-fitting result is compared with the positioning error threshold. If the deviation does not exceed the threshold, it indicates that the autonomous integrity monitoring result of the receiver is correct. Then, the pseudorange of the faulty satellite is generalized RDSS positioning in the above manner. The positioning result is cross-fitted with the generalized RDSS positioning result of the normal satellite. If the cross-fitting result does not exceed the threshold, it indicates that the faulty satellite is incorrectly identified and there is a false alarm. If it exceeds the threshold, it indicates that the current satellite is a faulty satellite. The autonomous integrity monitoring and verification is completed when the number of satellites is greater than 6.

[0035] In step (4), a generalized RDSS autonomous integrity monitoring process is implemented for cases where the number of available satellites is less than 6. The pseudorange observations of any two available RNSS satellites are packaged as observations for generalized RDSS positioning and sent to the ground processing center. The ground processing center performs three-sphere positioning calculations based on the pseudorange difference of the RNSS and the two-way ranging value of the RDSS, completing the generalized RDSS positioning. The pseudoranges of other available RNSS satellites are rotated for generalized RDSS positioning until all available RNSS satellites have completed pairwise generalized RDSS positioning calculations. All positioning calculation results are cross-fitted. If the cross-fitting result does not exceed a threshold, all satellites are considered normal; if the cross-fitting result exceeds the threshold, the RNSS satellite corresponding to the cross-fitting result of the generalized RDSS positioning calculation exceeding the threshold is selected, and this satellite is determined to be faulty. This completes the autonomous integrity monitoring for cases where the number of available satellites is less than 6. Finally, online real-time autonomous integrity monitoring is achieved based on the generalized RDSS positioning technology system, and the autonomous integrity monitoring identification and alarm results are output.

[0036] This method utilizes the unique generalized RDSS technology of the BeiDou system to achieve autonomous integrity monitoring in other dimensions, based on ordinary BeiDou dual-mode receivers. It is applicable to receivers with RNSS / RDSS dual-mode functionality, including ordinary BeiDou airborne dual-mode receivers, command-type BeiDou dual-mode user receivers, timing-type BeiDou dual-mode receivers, and anti-interference type BeiDou dual-mode receivers. It is simple, efficient, and widely applicable. This method is not limited to autonomous integrity monitoring of more than six satellites and is not constrained by satellite accuracy factors. It can effectively monitor various fault types, including fast-changing and slow-changing faults, and offers advantages such as high monitoring accuracy, strong real-time performance, and low false alarm rate.

[0037] Here is a more specific example:

[0038] A receiver autonomous integrity monitoring method based on generalized RDSS positioning, referring to Figure 1 and Figure 2 In this specific embodiment, satellites 1, 3, 5, 13, 21, 26, 27, 29, 59, and 61 of the BeiDou B3I frequency point are selected as visible satellites, among which satellite 1 is an unusable satellite, and satellites 13 and 21 are faulty satellites. The specific steps of this method are as follows:

[0039] Step 1: The receiver starts working according to the normal operating procedure, completes the reception of space-visible satellite signals, and receives all observation epoch data of the currently visible satellites participating in positioning, including satellite ephemeris, almanac, pseudorange and other observation data; after the receiver acquires, tracks and demodulates, it receives observation epoch data of 10 satellites: 1, 3, 5, 13, 21, 26, 27, 29, 59 and 61.

[0040] Step 2: After receiving the historical data of 10 visible satellites in space, satellite No. 1 is identified as an unusable satellite and is directly filtered out. Then, the receiver enters the autonomous integrity monitoring process. First, it determines whether the number of currently available satellites is greater than 6. The current number of available satellites is 9, which is greater than 6. The receiver then enters its own autonomous integrity monitoring process. The receiver monitors and identifies faulty satellites through its own odd-even vector integrity monitoring algorithm. After monitoring by the autonomous integrity algorithm, satellites No. 13 and No. 21 are identified as faulty satellites. The receiver removes these two satellites and continues to perform navigation and positioning calculations to obtain positioning results. At the same time, the generalized RDSS positioning process is started to verify and monitor the integrity of faulty satellites.

[0041] Step 3: The pseudoranges observed by satellites 27 and 29 are selected as the pseudorange observations of the RNSS for generalized RDSS positioning. The pseudorange measurements are packaged and sent to the ground processing center via message transmission. The ground processing center performs three-sphere positioning calculation based on the pseudorange difference of the RNSS and the two-way ranging value of the RDSS to obtain the generalized RDSS positioning result of the normal satellites. The positioning calculation result of the receiver is cross-fitted with the generalized RDSS positioning result of the normal satellites. The cross-fitting result is compared with the positioning error threshold, which is set to a positioning accuracy deviation of 10 meters. If the cross-fitting result is less than the threshold, it indicates that satellites 27 and 29 are normal satellites and the autonomous integrity monitoring result of the receiver is correct. Next, the pseudoranges of the faulty satellites 13 and 21 identified in the autonomous integrity check process are used for generalized RDSS positioning in the same manner as described above. The positioning results are then cross-fitted with the generalized RDSS positioning results of normal satellites. A threshold of 10 meters for positioning accuracy deviation is set. If the cross-fitting exceeds the threshold, it indicates that satellites 13 and 21 are faulty. This completes the autonomous integrity monitoring and verification when there are more than 6 satellites. If there are fewer than 6 usable satellites, the process directly transitions to the generalized RDSS autonomous integrity monitoring process. This ultimately completes the monitoring, identification, and verification of faulty satellites, improving the accuracy of autonomous integrity and the ability to suppress false alarms.

[0042] The working principle of this invention is as follows:

[0043] This invention, building upon traditional receiver autonomous integrity monitoring, fully utilizes the generalized RDSS positioning technology provided by the BeiDou Navigation Satellite System (BDS) to monitor and verify the integrity of visible satellites in space using a reliable two-way active positioning mode. For traditional autonomous integrity scenarios with more than six available satellites, it verifies and confirms faulty satellites identified during autonomous integrity monitoring, reducing the probability of false alarms. For autonomous integrity scenarios with fewer than six available satellites, it uses a pairwise combination of available satellites for generalized RDSS positioning to calculate pseudorange positioning. Faulty satellites are identified through cross-difference fitting of positioning results, thus completing the real-time monitoring and identification of receiver autonomous integrity. This method, employing the generalized RDSS positioning technology provided by the BeiDou Navigation Satellite System, is applicable to ordinary BeiDou dual-mode receivers, command-type BeiDou dual-mode receivers, timing-type BeiDou dual-mode receivers, and anti-interference BeiDou dual-mode receivers. It is simple, efficient, safe, reliable, and widely applicable. This method is not limited by the number of visible satellites, the accuracy factor of visible satellites, or the speed of failure of faulty satellites. It has good autonomous integrity monitoring effect for fault patterns such as single-satellite failure, multi-satellite failure, and slow-change satellite failure.

[0044] This invention utilizes the dual-mode RDSS / RNSS operation of a BeiDou dual-mode receiver and leverages the generalized RDSS positioning technology provided by the BeiDou system to achieve autonomous integrity monitoring of the receiver. This method does not rely on external auxiliary information or configuration environment support. Based on the traditional design architecture of the BeiDou dual-mode receiver, autonomous integrity monitoring is achieved through integration with generalized RDSS positioning technology. Compared with traditional receiver autonomous integrity monitoring methods, it offers advantages such as accurate integrity monitoring, independence from limitations imposed by the number of visible redundant satellites and accuracy factors, and support for multi-satellite fault monitoring.

Claims

1. A receiver autonomous integrity monitoring method based on generalized RDSS positioning, characterized in that, Includes the following steps: (1) The receiver starts working, completes the acquisition, tracking and demodulation of signals from all visible satellites in space, receives and stores all observation history data of all available satellites that can participate in positioning, including satellite ephemeris, almanac, and pseudorange observations. (2) Determine whether the number of available satellites is greater than 6. If the number of available satellites is greater than 6, then the faulty satellites are monitored and identified by calculating and accumulating the odd and even vectors, the faulty satellites are removed, the navigation and positioning solution is completed, and then the process proceeds to step 3 to continue monitoring and verifying the generalized RDSS of the faulty satellites. If the number of available satellites is less than 6, then the process proceeds to step 4. (3) The pseudorange observations of the satellites identified as normal satellites participating in the navigation and positioning calculation are packaged as the pseudorange observations of the RNSS for generalized RDSS positioning and sent to the ground processing center. The ground processing center performs three-sphere positioning calculation based on the pseudorange difference of the RNSS and the two-way ranging value of the RDSS to obtain the generalized RDSS positioning result of the normal satellite. The positioning calculation result of the receiver is cross-fitted with the generalized RDSS positioning result of the normal satellite. The cross-fitting result is compared with the positioning error threshold. If the deviation does not exceed the threshold, it indicates that the autonomous integrity monitoring result of the receiver is correct. The observation pseudoranges of the identified faulty satellites are used for generalized RDSS positioning. The positioning results are then cross-fitted with the generalized RDSS positioning results of normal satellites. If the cross-fitting result does not exceed the threshold, it indicates that the faulty satellite was incorrectly identified and there is a false alarm. If the cross-fitting result exceeds the threshold, it indicates that the current satellite is a faulty satellite. Complete autonomous integrity monitoring and verification when there are more than 6 satellites; (4) Pack the pseudorange observations of any two available RNSS satellites as pseudorange observations for generalized RDSS positioning and send them to the ground processing center. The ground processing center performs three-sphere positioning calculation based on the pseudorange difference of RNSS and the two-way ranging value of RDSS to complete the generalized RDSS positioning. Then, the pseudoranges of other available RNSS satellites are rotated for generalized RDSS positioning until all available RNSS satellites have completed the generalized RDSS positioning calculation by combining pairs of satellites. All positioning results are cross-fitted. If the cross-fitting result does not exceed the threshold, it means that all satellites are normal. If the cross-fitting result exceeds the threshold, select the RNSS satellites whose cross-fitting results of generalized RDSS positioning exceed the threshold and determine that the satellite is a faulty satellite. Complete autonomous integrity monitoring when the number of available satellites is less than 6.

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