CN115166781A - A method for monitoring the integrity of the PNT network based on the cooperation between the sky and the earth - Google Patents

Abstract

The invention discloses a method for monitoring the integrity of a PNT network in cooperation with heaven and earth. The method is based on the coordinated positioning, navigation and timing network composed of the ground-based navigation system, and establishes a comprehensive PNT integrity monitoring system by analyzing various error sources and integrity risk models of the navigation system. The integrity of ground-based navigation source signals and information solves the problem of rapid monitoring of the global domain integrity of the Beidou navigation system; the service segment has designed a unified mathematical representation method for high-precision product integrity in the service segment; the user segment integrates multi-source heterogeneous sensors to achieve indoor External seamless high-precision positioning autonomous integrity algorithm. The invention breaks through the integrity restriction bottleneck of the application of the sky-earth coordinated PNT network in the fields of unmanned driving and artificial intelligence, and fills the current technical gap in the integrity monitoring algorithm of the comprehensive PNT network at home and abroad.

Description

A method for monitoring the integrity of the PNT network based on the cooperation between the sky and the earth

technical field

The invention relates to a high-precision integrity monitoring method suitable for a sky-earth coordinated PNT network, belonging to the field of satellite navigation, indoor and outdoor integrated positioning and integrity monitoring.

Background technique

High-precision location information has played an important role in promoting the development of the national economy, and has broad market application needs in the field of unmanned driving and artificial intelligence. At present, outdoor positioning mainly relies on satellite navigation systems mainly based on BDS and GPS, while indoor positioning is realized by navigation systems such as pseudolites and ultra-wideband. Aiming at the problems that the systems of various positioning sources are not unified and the positioning means are not integrated, it is urgent to establish a more ubiquitous, integrated and intelligent comprehensive navigation system. Based on space-based navigation systems such as GNSS/LEO, and ground-based navigation systems such as pseudolites/ultra-wideband/5G, the Space-Earth Collaborative PNT network solves the key issues of unification of space-time benchmarks, coordination of signal systems, and fusion of positioning methods, thereby building a coordinated positioning and navigation system for space and Earth. and timing network.

Integrity refers to the ability to issue an alarm to the user in a timely manner when the navigation system fails or the error exceeds the limit. It is one of the important evaluation indicators of the navigation system. In civil aviation, precision approach, intelligent transportation, emergency response, etc. applications are of great value. The existing SBAS and GBAS integrity models are aimed at monitoring the integrity of a single GNSS satellite-based enhanced positioning system and ground-based enhanced system, which cannot meet the integrity of the PNT network that integrates new elements such as low-orbit, pseudolites, and multi-source sensors. sexual needs. At present, domestic and foreign research institutions are committed to the research of comprehensive PNT network structure and positioning system, but have not yet formed a relatively mature integrity monitoring scheme and model.

SUMMARY OF THE INVENTION

Aiming at the problems that the current outdoor positioning and indoor positioning methods are not coordinated, and the comprehensive PNT network integrity monitoring method is immature, the indoor and outdoor joint positioning is not unified and the positioning service risk is uncontrollable, and a high-precision sky-earth cooperative PNT network is proposed. Integrity monitoring method. The method mainly divides the PNT network into system segment, service segment and user segment, and conducts research on key technologies of integrity monitoring respectively, so as to establish a unified indoor and outdoor high-precision, high-reliability integrity positioning service.

The present invention is achieved through the following technical solutions:

A high-precision integrity monitoring method for a sky-earth cooperative PNT network, comprising the following steps:

(1) Build a PNT network based on GNSS and pseudolites. By analyzing the positioning principles and error sources of various navigation systems, a three-level integrity monitoring model is established, which is divided into system segment integrity monitoring and service segment integrity monitoring. Monitoring and user segment integrity monitoring;

(2) In the system section, a permanent observation station is set up on the ground to monitor the navigation source information and signal integrity. And by installing on-board monitoring receivers on low-orbit satellites, rapid monitoring of the global domain integrity of the Beidou navigation system can be achieved. At the same time, low-orbit satellite-based integrity monitoring has the advantage of not being affected by ground interference sources;

(3) The high-precision products in the service segment include GNSS precise satellite orbits, precise satellite clock errors, and precise pseudo-satellite clock errors. By means of error modeling and parameter estimation, the base station residuals are solved, and a unified representation of the integrity of high-precision products in the service segment is established. Model;

(4) User segment integrity monitoring By fusing multi-source sensors, the sensor position is estimated in real time by the method of robust Kalman filtering, so as to solve the problem of fault identification and processing in the case of navigation signal degradation/failure, and calculate the user positioning protection level, Realize indoor and outdoor integrated high-precision positioning integrity monitoring;

(5) On the basis of the PNT network in cooperation with the sky and the earth, the integrity monitoring method of the system segment, the service segment and the user segment is integrated to establish a system that alerts the user within a specified time when the user positioning protection level exceeds the limit within the determined risk level. Integrity of service.

Further, the concrete mode of step (1) is:

(101) The space-terrestrial collaborative PNT network includes space-based navigation sources and ground-based navigation sources. The space-based navigation source mainly refers to the global satellite navigation system GNSS, and the ground-based navigation source mainly refers to the pseudolite positioning system. By unifying the time and space benchmarks between different positioning methods, and integrating a variety of indoor and outdoor positioning methods, a PNT service network that is coordinated between the sky and the ground is established;

(102) The error terms that affect the integrity of the PNT network include landing signal power deviation, S-curve zero-crossing deviation, space signal ranging error, precision satellite orbit error, precision satellite clock error, phase deviation, multipath effect, receiver observation error, etc. By classifying the above fault sources, the integrity monitoring system can be divided into system segment integrity monitoring, service segment integrity monitoring and user segment integrity monitoring;

Further, the concrete mode of step (2) is:

(201) In order to monitor the signal and information integrity of the PNT network system segment of the sky-earth coordination, GNSS monitoring stations are set up outdoors and pseudolite monitoring stations are set up indoors to monitor landing signal power deviation, S-curve zero-crossing deviation, and signal-in-space ranging. Accuracy and other error sources. Perform integrity monitoring and integrity status identification for each navigation satellite and pseudolite respectively, and mark the system integrity status when the number of failures of navigation satellites or pseudolites reaches a certain proportion;

(202) Since Beidou ground monitoring stations cannot be deployed around the world and cannot directly monitor overseas navigation satellites, the Beidou system integrity monitoring cycle is too long. A low-orbit navigation augmentation constellation is designed, and monitoring receivers are mounted on low-orbit satellites to monitor the integrity of the entire constellation of the Beidou navigation system in real time. Compared with ground monitoring methods, low-orbit satellite-based monitoring has the advantage of not being affected by ground interference signals and error sources. At the same time, Beidou/GNSS enhanced by low-orbit navigation can improve the integrity performance of the entire space-based navigation system;

Further, the concrete way of step (3) is:

(301) The base station continuously tracks GNSS satellites and pseudolites, corrects errors such as antenna phase deviation, relativistic effects, and tidal effects by means of error modeling, and determines receiver clock errors and tropospheric delays based on parameter estimation. Use observation residuals to represent the combined errors of GNSS/LEO precision satellite orbits, precision satellite clock errors, and pseudolite precision clock errors;

(302) Perform mathematical statistical analysis on the residual of the base station by using the envelope method, and determine the mathematical expectation, variance and probability distribution density. Under a certain confidence probability level, when the residual error of the base station exceeds the limit, it means that the high-precision products in the service segment are abnormal; otherwise, it means that the high-precision products in the service segment are normal. Evaluate high-precision products through the residuals of the base station, so as to establish a unified representation model of the integrity of the service segment;

Further, the concrete mode of step (4) is:

(401) Constructing a flexible PNT user positioning terminal by fusing multi-source heterogeneous sensors. Combine pseudorange, carrier phase observations, acceleration and angular velocity observations to estimate the location information of the elasticized PNT user terminal by means of robust Kalman filtering, identify and process the fault observations, and implement an autonomous integrity positioning algorithm for the user terminal;

(402) After identifying and eliminating the fault observations, the elasticized PNT user terminal calculates the user positioning protection level based on the observation conditions and the integrity parameters broadcasted by the service segment, including the vertical protection level and the horizontal protection level. When the positioning protection level When the alarm threshold is exceeded, a warning is issued.

The beneficial effects of the present invention are:

1. Aiming at the problem that the current integrity monitoring method cannot meet the integration of multiple positioning methods and the unified indoor and outdoor positioning, the present invention designs a method for monitoring the integrity of the PNT network in coordination with the sky and the ground, and unifies various GNSS/LEO/PL/INS. The time and space benchmarks of the positioning means are used to construct the PNT network of space-earth coordination.

2. The present invention establishes a three-level integrity monitoring model of the system segment, the service segment and the user segment according to the fault tree characteristics of the PNT network in cooperation with the sky and the earth. By arranging GNSS/LEO/PL receivers on the ground and designing a low-orbit navigation augmentation constellation, the rapid integrity monitoring of BeiDou/GNSS signals and information is realized.

3. The present invention uses the method of error modeling and parameter estimation to determine the residual error of the observation station, and establishes a unified integrity representation model of the high-precision products in the service section.

4. The present invention fuses multi-source heterogeneous sensors, estimates the user terminal location in real time and identifies abnormal observation values by means of robust Kalman filtering, and calculates the location protection level in combination with service segment integrity parameters and observation conditions.

5. The present invention integrates the system segment, service segment and user segment integrity monitoring method, and establishes an integrity service that alerts the user within a specified time when the user positioning protection level exceeds the limit within the determined risk level, thereby breaking through the cooperation between heaven and earth The application of PNT network to the integrity of unmanned driving, artificial intelligence and other fields restricts the bottleneck, filling the current technical gap in the integrity monitoring algorithm of comprehensive PNT network at home and abroad.

Description of drawings

FIG. 1 is a flowchart of a method for monitoring the integrity of a PNT network in an embodiment of the present invention.

Detailed ways

In order to better illustrate the purpose and advantages of the present invention, the technical solutions of the present invention are further described below with reference to the accompanying drawings and specific embodiments.

A high-precision integrity monitoring method for a sky-earth cooperative PNT network. A variety of navigation system error sources and integrity risk models are established to establish a comprehensive PNT integrity monitoring system, which is divided into system segment integrity monitoring, service segment integrity monitoring, and user segment integrity monitoring. The system section is based on GNSS/LEO/pseudolite/ultra-wideband/5G reference stations, monitors the signal and information integrity of space-based and ground-based navigation sources, and uses the short-period characteristics of low-orbit constellation orbits to solve the global domain integrity of Beidou navigation system quickly. Monitoring challenges. In the service section, the residuals of the base station are obtained by means of error modeling and parameter estimation, and a unified mathematical representation method of high-precision product integrity in the service section is designed. The user segment integrates multi-source heterogeneous sensors to realize the autonomous integrity algorithm for seamless indoor and outdoor high-precision positioning.

As shown in Figure 1, the specific steps of the method are as follows:

(1) Based on the space-based navigation source and the ground-based navigation source, build a PNT network of sky-earth coordination, and establish a three-level integrity monitoring system, which is the integrity monitoring of the system segment, the integrity monitoring of the service segment, and the integrity monitoring of the user segment;

(101) Space-based navigation sources include the global satellite navigation system GNSS dominated by Beidou/GPS/GLONASS/GALILEO, and low-orbit satellite navigation augmentation system LEO, and ground-based navigation sources include pseudolite positioning system PL, ultra-wideband positioning system and 5G base station. By unifying the time reference T _sys and the spatial reference X _sys between different positioning means, and integrating a variety of indoor and outdoor positioning methods F (T _sys , X _sys ), a PNT service network of space-earth coordination is established;

(102) The error sources of the sky-earth cooperative PNT network mainly include the landing signal power deviation S _bias , the S-curve zero-crossing point deviation SCB, the space signal ranging error SISRE, the precision satellite orbit error ΔX ^GNSS , ΔX ^LEO , ΔX ^PL , and the precision satellite clock error ΔT ^GNSS , ΔT ^LEO , ΔT ^PL , phase deviation FCB, multipath effect MP, receiver observation error ε, etc. By classifying the above error sources, the integrity monitoring model can be divided into system segment integrity monitoring, service segment integrity monitoring, and user segment integrity monitoring;

(2) Integrity monitoring of the system segment is to set up GNSS/LEO/PL permanent observation stations in the open ground environment or indoors to monitor the information and signal integrity of space-based navigation sources and ground-based navigation sources. Install on-board monitoring receivers on low-orbit satellites, and use the short-period characteristics of low-orbit constellation orbits to solve the problem of rapid integrity monitoring of the Beidou navigation system due to the difficulty of deploying stations around the world. When a navigation signal or abnormal information is detected, a warning is sent to the integrity monitoring model, otherwise, the next monitoring stage is entered;

当导航卫星或者伪卫星故障个数达到一定比例时，对系统完好性状态

进行标识：(201) By arranging GNSS/LEO monitoring stations outdoors and PL monitoring stations indoors, they are used to monitor error sources such as landing signal power deviation S _bias , S curve zero-crossing point deviation SCB, and signal-in-space ranging error SISRE. Integrity monitoring and integrity status identification for each GNSS/LEO navigation satellite and PL satellite respectively

When the number of failures of navigation satellites or pseudolites reaches a certain proportion, the system integrity status is

To identify:

是导航系统中第i颗卫星的信号和信息完好性标识，当所监测的卫星信号和信息正常是为1，异常时为0。In the formula,

It is the signal and information integrity indicator of the i-th satellite in the navigation system. It is 1 when the monitored satellite signal and information are normal, and 0 when it is abnormal.

In the formula, H ^system is the integrity indicator of the navigation system. When the number of normal working satellites exceeds 80%, the navigation system is normal, which is represented by 1. When the number of normal operating satellites is less than 80%, the navigation system is abnormal, which is represented by 0.

(202) Design a low-orbit navigation augmentation constellation. The constellation consists of 4 orbital planes with orbital inclinations differing by 45°, and each orbital plane has 3 satellites with true anomalies differing by 120°, and the orbital altitude is 1000 kilometers. . Install a monitoring receiver in the negative direction of the Z-axis of the LEO satellite, and use the characteristics of the short orbital period of the low-orbit satellite to monitor the integrity of the entire constellation of the Beidou Navigation System in real time:

where T is the orbital period, GM is the Earth's gravitational constant, and a is the orbital height. For Beidou MEO satellites, the orbital period is about 12.9 hours, and for LEO satellites with an orbital altitude of 1000 km, the orbital period is about 1.7 hours. Through simulation analysis, the low-orbit constellation designed by the present invention can monitor the integrity of the entire constellation of the Beidou navigation system in real time. At the same time, the LEO satellite-based integrity monitoring has the advantage of not being affected by the ground interference signal IFS and the multipath error source MP. LEO-enhanced BeiDou/GNSS can improve the integrity performance of the entire space-based navigation system, including minimum detectable deviation and failure detection rate;

(3) High-precision products in the service segment include GNSS precision satellite orbit X ^GNSS , precision satellite clock error ΔT ^GNSS and pseudolite precision clock error ΔT ^PL , and the GNSS/LEO/PL reference station residuals are solved by error modeling and parameter estimation. , so as to establish a unified representation model of high-precision product integrity in the service segment. When the abnormality of the high-precision products in the service segment is detected, a warning is sent to the integrity monitoring model, otherwise, the next monitoring stage is entered;

(301) The base station continuously tracks the GNSS satellites and pseudolites PL, corrects the antenna phase center deviation δ _pco , relativistic effect δ _rel , tidal effect δ _tide and other errors by means of error modeling, and determines the receiver clock error based on the method of parameter estimation _ΔTr , tropospheric delay Trop. Use the residuals of observations to represent the combined errors of the GNSS/LEO precise satellite orbit X ^GNSS/LEO , the precise satellite clock error ΔT ^GNSS/LEO and the pseudolite precise clock error ΔT ^PL : v ^GNSS/LEO =P-ρ+c·ΔT ^GNSS/LEO -c·ΔT _r +Trop+δ _pco +δ _rel +δ _tide

v ^PL =P-ρ+c·ΔT ^PL -c·ΔT _r

In the formula, ^vGNSS/LEO is the comprehensive error of GNSS or LEO satellite, vPL is the comprehensive error of pseudolite ^PL , P is the GNSS/LEO/PL pseudorange observation value, and ρ is the distance from the receiver to the GNSS/LEO/PL satellite. Geometric distance, c is the speed of light.

(302) Perform mathematical statistical analysis on the residual of the base station by using the envelope method, and determine the mathematical expectation, variance and probability distribution density. Under a certain confidence probability level, when the residual error of the base station exceeds the limit, it means that the high-precision products in the service segment are abnormal; otherwise, it means that the high-precision products in the service segment are normal. Evaluate high-precision products through the residuals of the base station, so as to establish a unified representation model of the integrity of the service segment;

(302) Use the envelope method to perform mathematical statistical analysis on the residual v of the base station, and determine the mathematical expectation E(v), the standard σ(v) and the probability distribution density f(v):

Under a certain confidence probability level, when the residual error of the base station exceeds the limit, it means that the high-precision products in the service segment are abnormal; otherwise, it means that the high-precision products in the service segment are normal. The high-precision products are evaluated by the residuals of the base station, so as to establish a unified representation model of the integrity of the service segment:

In the formula, H ^product is the high-precision product integrity mark of the service segment. When the residual standard deviation statistic σ[v(t)] at time t does not exceed the limit, H ^product = σ[v(t)], when the residual error at time t is When the standard deviation statistic exceeds the limit, H ^product = 0, indicating that the integrity is abnormal.

(4) User segment integrity monitoring By fusing multi-source sensors, the sensor position X is estimated in real time by the method of robust Kalman filtering, so as to solve the problem of fault identification and processing in the case of GNSS/PL signal degradation and failure, and calculate the user location. The protection level is σ _PL , and IO-RAIM can realize high-precision positioning and integrity monitoring of indoor and outdoor integration;

(401) In order to solve the problem that a single positioning method is difficult to achieve complete positioning in indoor and outdoor and urban complex environments, a flexible PNT user positioning terminal is constructed by integrating multi-source sensors such as GNSS/LEO/PL/INS. Combined with the observation vector Obs composed of the pseudorange observation value P of GNSS/LEO/PL, the carrier phase observation value L, and the acceleration a and angular acceleration observation value w of INS, the elasticized PNT user terminal position is estimated by the method of robust Kalman filter. X, identify and process the fault observation value Δ, and implement the user-side autonomous integrity positioning algorithm:

Obs=AX-V

In the above formula, matrix A is a parameter estimation coefficient matrix composed of observed values, and V is a residual vector. When the ith residual vector exceeds the limit 2×H ^product , the observation is considered to be a fault observation, otherwise it is regarded as a normal observation.

(402) After identifying and eliminating the fault observation value Δ, the elasticized PNT user terminal calculates the user positioning protection level σ _PL based on the observation conditions and the high-precision product integrity parameter H ^product broadcast by the service segment, including the horizontal protection level σ _HPL and the vertical protection level σ _VPL :

σ _PL = 3 × H ^porduct × PDOP

σ _HPL = 3 × H ^porduct × HPDOP

σ _VPL = 3 × H ^porduct × VPDOP

In the formula, PDOP is the positioning precision factor generated according to the observation conditions, HDOP is the positioning precision factor in the horizontal direction, and VDOP is the positioning precision factor in the vertical direction. When the location protection level exceeds the alarm threshold, a warning is issued to the user, thereby avoiding the integrity risk caused by missing alarms.

By analyzing the positioning principles and fault trees of multiple navigation systems such as GNSS, LEO, pseudolites, inertial navigation, etc., the method unifies the time and space benchmarks of various positioning systems, and establishes the signal and information monitoring of the system segment respectively, with high precision in the service segment. The three-level integrity model for product monitoring and user segment autonomous positioning integrity monitoring solves the problem of unified representation of the integrity models of different positioning systems, and provides a high-precision and high-reliability positioning service guarantee for the PNT network.

In a word, the present invention solves the inconsistency of the monitoring methods for the integrity of various positioning means in the integrated PNT network, the long period of monitoring the integrity of the Beidou navigation system in the global domain, the difficulty of uniformly expressing the integrity of high-precision products in the service section, and the integrity of the indoor and outdoor integration of the user section. Sexual monitoring technology is immature and other problems. The invention is suitable for application scenarios involving the safety of users' life and property, such as civil aviation, precision approach, unmanned driving, intelligent transportation, disaster rescue, etc., and has important value in national economic construction and safety guarantee.

Specific embodiments of the present invention have been described above in detail. It should be understood that those skilled in the art can make many changes and modifications according to the concept of the present invention without creative efforts. Therefore, any technical solutions that can be obtained by those skilled in the technical field through logical analysis, reasoning or limited experiments on the basis of the prior art according to the concept of the present invention shall fall within the protection scope determined by the claims.

Claims (5)

1. a method for monitoring the integrity of the PNT network in coordination with heaven and earth, is characterized in that, comprises the steps: (1) Build a PNT network based on GNSS and pseudolites. By analyzing the positioning principles and error sources of various navigation systems, a three-level integrity monitoring model is established, which is divided into system segment integrity monitoring and service segment integrity monitoring. Monitoring and user segment integrity monitoring; (2) Integrity monitoring of the system segment Set up permanent observation stations on the ground to monitor the integrity of navigation source information and signals, and install on-board monitoring receivers on low-orbit satellites to quickly monitor the global domain integrity of the Beidou Navigation System; (3) Establish high-precision products in the service section, including GNSS precision satellite orbits, precision satellite clock errors, and pseudolite precision clock errors, and solve the base station residuals through error modeling and parameter estimation, and establish high-precision products in the service section. Sexual unified representation model; (4) User segment integrity monitoring By fusing multi-source sensors, the sensor position is estimated in real time by the method of robust Kalman filtering, so as to solve the problem of fault identification and processing in the case of navigation signal degradation/failure, and calculate the user positioning protection level, Realize indoor and outdoor integrated high-precision positioning integrity monitoring; (5) On the basis of the PNT network based on the cooperation between the sky and the earth, the integrity monitoring method of the system segment, the service segment and the user segment is integrated, and a method is established within the determined risk level, when the user positioning protection level exceeds the limit, the user is alerted within a specified time. Integrity of service. 2 . The method for monitoring the integrity of the PNT network in coordination with the sky and the ground according to claim 1 , wherein the specific method of step (1) is: (101) The space-ground collaborative PNT network includes space-based navigation sources and ground-based navigation sources. The space-based navigation source is the global satellite navigation system GNSS, and the ground-based navigation source is the pseudolite positioning system; by unifying the time reference and space reference between different positioning means , Integrate a variety of indoor and outdoor positioning methods to establish a PNT service network that is coordinated by the sky and the ground; (102) The error terms that affect the integrity of the PNT network of the space-earth coordination include landing signal power deviation, S-curve zero-crossing deviation, space signal ranging error, precision satellite orbit error, precision satellite clock error, phase deviation, multipath effect, receiver Observe errors, classify these error terms, and divide the integrity monitoring system into system segment integrity monitoring, service segment integrity monitoring, and user segment integrity monitoring. 3 . The method for monitoring the integrity of the PNT network in accordance with claim 1 , wherein the specific method of step (2) is: (201) In order to monitor the signal and information integrity of the PNT network system segment of the sky-earth collaboration, GNSS monitoring stations are set up outdoors and pseudolite monitoring stations are set up indoors to monitor landing signal power deviation, S-curve zero-crossing deviation, and signal-in-space ranging. Accuracy: Integrity monitoring and integrity status identification are performed for each navigation satellite and pseudolite respectively, and the system integrity status is identified when the number of failures of navigation satellites or pseudolites reaches a preset proportion; (202) Because Beidou ground monitoring stations cannot be deployed around the world and cannot directly monitor overseas navigation satellites, the Beidou system integrity monitoring cycle is too long. The low-orbit navigation augmentation constellation is used, and monitoring receivers are mounted on low-orbit satellites to achieve real-time monitoring. Monitor the integrity of the entire constellation of the Beidou Navigation System. 4 . The method for monitoring the integrity of the PNT network in coordination with the sky and the earth according to claim 1 , wherein the specific method of step (3) is: (301) The base station continuously tracks GNSS satellites and pseudolites, corrects the errors of antenna phase deviation, relativistic effect, and tidal effect by means of error modeling, and determines the receiver clock error and tropospheric delay based on the method of parameter estimation. Difference to represent the comprehensive error of GNSS/LEO precision satellite orbit, precision satellite clock error and pseudolite precision clock error; (302) Use the envelope method to perform mathematical statistical analysis on the residuals of the base station to determine the mathematical expectation, variance and probability distribution density; when the residuals of the base station exceed the limit, it means that the high-precision products in the service section are abnormal, otherwise, it means that the service section is high The precision products are normal; the high-precision products of the service segment are evaluated by the residuals of the base station, so as to establish a unified representation model of the integrity of the service segment. 5 . The method for monitoring the integrity of the PNT network in coordination with heaven and earth according to claim 1 , wherein the specific method of step (4) is: (401) Construct flexible PNT user terminal by fusing multi-source heterogeneous sensors; combine pseudorange, carrier phase observations, and acceleration and angular velocity observations to estimate flexible PNT user terminal location information using robust Kalman filtering , identify and process the fault observations, and implement the user-side autonomous integrity positioning algorithm; (402) After identifying and eliminating the fault observations, the elasticized PNT user terminal calculates the user positioning protection level based on the observation conditions and the integrity parameters broadcasted by the service segment, including the vertical protection level and the horizontal protection level. When the positioning protection level When the alarm threshold is exceeded, a warning is issued.

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