Navigation satellite UERE monitoring method based on multi-station asynchronous observation data

Abstract

The invention provides a navigation satellite UERE monitoring method based on multi-station asynchronous observation data. The method comprises the following steps: calculating according to a geometric distance and various error correction values to obtain a pseudo-range calculation value; subtracting the pseudo-range observation value from the pseudo-range calculation value to obtain a pseudo-range observation value subtraction calculation value OMC; then subtracting an OMC median of the epoch from the OMC of each satellite in the same epoch based on a median station clock elimination method to obtain a single-station UERE of each satellite; and finally, calculating the minimum value of the UERE absolute values of the satellite to be monitored in all observation stations of the same epoch based on a minimum multi-station synthesis method, and taking the corresponding value as the final UERE monitoring result of the epoch of the satellite. According to the method, the requirement and dependence of UERE monitoring on tracking station clock synchronization are reduced, the station selection range of UERE monitoring is expanded, the station selection redundancy and uniformity of UERE monitoring are improved, and global continuous monitoring of navigation satellites such as Beidou is realized; and meanwhile, the accuracy and the reliability of the global continuous monitoring result of navigation satellites such as Beidou and the like UERE are improved.

Description

Technical Field

[0001] The present invention relates to the field of measurement and testing technology, and in particular to a navigation satellite UERE monitoring method based on multi-station asynchronous observation data. Background Art

[0002] User Equivalent Range Error (UERE) is a comprehensive error in the satellite-to-user distance observation caused by the navigation satellite orbit, clock error, atmospheric propagation, user observation, etc. It is an important parameter for evaluating the service performance of the navigation satellite downlink signal and an important indicator for monitoring the integrity of the navigation satellite downlink signal.

[0003] The satellite navigation system determines the user's position by measuring the propagation time of the satellite signal to the user's antenna (multiplied by the speed of light to get the distance) based on the accurate satellite position and time. In order to determine the user's three-dimensional position and the user's clock error, at least four satellites need to be observed. Position Dilution of Precision (PDOP) is a parameter that characterizes the geometric strength of the relative position relationship between the satellite and the user. The user's positioning accuracy can be simply expressed as UERE*PDOP. The number of satellites in the navigation constellation and the orbit design determine the constellation's PDOP value performance. The sources of UERE include various error sources in the space segment, control segment, and user segment: ① satellite clock error; ② satellite orbit error; ③ satellite hardware bias; ④ ionosphere error; ⑤ troposphere error; ⑥ multipath effect error; ⑦ receiver hardware bias, etc. A smaller UERE value indicates a higher positioning accuracy. In practical applications, UERE can be used to evaluate positioning accuracy, analyze errors, formulate positioning requirements, and monitor satellite performance and integrity.

[0004] With the development of the Global Navigation Satellite System (GNSS) system and its applications, the number of satellite navigation systems available for selection has increased. However, after the occurrence of integrity events such as the GPS timing anomaly in 2016, the GLONASS ephemeris injection error in 2014, and the Galileo service interruption time of about 117 hours in 2019, both GNSS suppliers and users have paid more and more attention to the monitoring and alarm capabilities of the operating status of the GNSS system. The user equivalent range error is an important indicator for monitoring the integrity of the navigation satellite downlink signal. The existing navigation satellite UERE monitoring technology has the following problems: the user equivalent range error is calculated based on the monitoring station with strict synchronization of the station clock, and the UERE results of each monitoring station are independent of each other. An independent single station can only monitor the satellites within the zenith visible range of the station. Especially for the navigation system with only regional ground monitoring stations, it is impossible to monitor the UERE of all satellites in the entire constellation at the same time. At the same time, the data quality will be reduced or the data will be abnormal due to the single station's own receiving equipment or the surrounding environment, resulting in false alarms or missed alarms. This problem is particularly prominent for GNSS suppliers that have a limited number of ground monitoring stations (with strictly synchronized station clock times), uneven global distribution, or even only regional monitoring stations.

[0005] Currently, there are relatively abundant data resources from global tracking stations that can be used for UERE monitoring. However, there are problems such as station clock asynchrony (i.e., the true clock error of the station receiver is unknown) and uneven quality of observation data. How to improve the accuracy and continuity of global monitoring results of navigation satellite UERE while making full use of global tracking station data resources has become an urgent problem to be solved. Summary of the invention

[0006] The present invention aims to solve the accuracy and continuity of UERE global monitoring results, and provides a navigation satellite UERE monitoring method based on multi-station asynchronous observation data, reduces the requirements and dependence of UERE monitoring on tracking station clock synchronization, expands the station selection range of UERE monitoring, improves the redundancy and uniformity of UERE monitoring station selection, and realizes global continuous monitoring of Beidou and other navigation satellite UERE; at the same time, the multi-station UERE comprehensive method provided greatly reduces the monitoring false alarms or missed alarms caused by factors such as the equipment of a single measuring station itself or the surrounding environment, and improves the accuracy and reliability of the global continuous monitoring results of Beidou and other navigation satellite UERE.

[0007] The present invention provides a navigation satellite UERE monitoring method based on multi-station asynchronous observation data, comprising the following steps:

[0008] S1. Read the observation data of the tracking station to obtain the pseudo-range observation value of the navigation signal frequency j of the satellite s measured by the tracking station terminal r at a certain epoch time:

[0009] S2, read the broadcast ephemeris to calculate the satellite's fixed coordinates at the time of signal transmission and perform earth rotation correction, and calculate the true geometric distance from the satellite to the measuring station based on the satellite coordinates and the known coordinates of the tracking station terminal r;

[0010] According to the known coordinates of the receiver, the navigation message, and the atmospheric correction model, the satellite clock error calculation value, the tropospheric delay error calculation value, the ionospheric delay error calculation value, the relativistic effect correction calculation value, and the satellite code hardware delay calculation value are obtained;

[0011] The pseudorange calculation value is obtained based on the true geometric distance from the satellite to the station, the satellite clock error calculation value, the tropospheric delay error calculation value, the ionospheric delay error calculation value, the relativistic effect correction calculation value, and the satellite code hardware delay calculation value.

[0012] S3, the pseudo-range observation value Pseudorange calculation value Subtract the pseudorange observation value from the calculated value

[0013] Return to step S1 and cyclically calculate the pseudorange observation value minus the calculated value of all satellites at the same epoch time After the calculation is completed, all pseudorange observations minus the calculated values ​​are stored. Go to step S4;

[0014] S4, tracking station terminal r at epoch time n satellites The values ​​are sorted from small to large, S = 1, 2, ..., n, and the pseudorange observation value minus the calculated value sequence is obtained according to the sorting result:

[0015] OMC1≤OMC2≤…≤OMC n-1 ≤OMC n ;

[0016] S5. Calculate the OMC median Mdn(OMC) based on the pseudorange observation value minus the calculated value sequence;

[0017] S6. The epoch time of each satellite Subtract the median Mdn(OMC) of the OMC sequence at the epoch time to obtain the UERE of each satellite;

[0018] Return to step S1, traverse all tracking station terminals r, and obtain the satellites observed by all tracking stations at the epoch time

[0019] S7. Use the minimum value multi-station comprehensive method to obtain the UERE monitoring results after multi-station comprehensive analysis

[0020]

[0021] Among them, Min() is the minimum value function, || is the absolute value, and m is the total number of tracking station terminals that observe satellite S;

[0022] A navigation satellite UERE monitoring method based on multi-station asynchronous observation data was completed.

[0023] The navigation satellite UERE monitoring method based on multi-station asynchronous observation data described in the present invention is, as a preferred embodiment, in step S1,

[0024]

[0025] in, is the geometric distance between the satellite and the ground, dt r is the receiver clock error, dt s is the satellite clock error, is the tropospheric delay error, μ j is the ionospheric delay influence coefficient of frequency point j, is the ionospheric delay error, d rela is the correction for relativistic effects, d r,j is the receiver code hardware delay, This is the satellite code hardware delay. is the multipath error.

[0026] The navigation satellite UERE monitoring method based on multi-station asynchronous observation data described in the present invention is, as a preferred embodiment,

[0027]

[0028] Among them, f1 is the default frequency of ionospheric delay error.

[0029] The navigation satellite UERE monitoring method based on multi-station asynchronous observation data described in the present invention is, as a preferred mode, in steps S1 and S2, after reading the tracking station observation data and the navigation ephemeris, pseudo-random noise code (PRN) matching and time matching are performed in the navigation ephemeris according to the satellite PRN number read from the observation data. After the matching is successful, the parameters such as the satellite coordinates, satellite clock difference and satellite station geometric distance are calculated. If the matching is unsuccessful, the ephemeris is continued to be read for matching until the ephemeris data ends.

[0030] The navigation satellite UERE monitoring method based on multi-station asynchronous observation data described in the present invention is, as a preferred embodiment, in step S2,

[0031]

[0032] in, is the calculated value of the satellite-to-ground geometric distance, is the satellite clock error calculation value, is the calculated value of tropospheric delay error, is the calculated value of ionospheric delay error, is the calculated value corrected for relativistic effects, Calculated value of satellite code hardware delay.

[0033] The navigation satellite UERE monitoring method based on multi-station asynchronous observation data described in the present invention is, as a preferred embodiment, in step S3,

[0034]

[0035] in, is the comprehensive residual error, Including navigation message parameter errors, atmospheric delay correction residual errors, measurement noise and multipath errors.

[0036] The navigation satellite UERE monitoring method based on multi-station asynchronous observation data of the present invention is preferably used in step S4 to first determine whether the number of satellites is greater than or equal to 2. If so, If not, return to step S1.

[0037] The navigation satellite UERE monitoring method based on multi-station asynchronous observation data described in the present invention is, as a preferred embodiment, in step S5,

[0038]

[0039] The navigation satellite UERE monitoring method based on multi-station asynchronous observation data described in the present invention is, as a preferred embodiment, in step S6,

[0040]

[0041] in, is the comprehensive residual error, Including navigation message parameter residual error, atmospheric delay correction residual error, measurement noise residual error and multipath residual error.

[0042] The present application discloses a navigation satellite user equivalent range error (UERE) monitoring method based on multi-station asynchronous observation data. The method comprises the following steps: firstly, reading the observation data of the global tracking station whose station clock is not synchronized to obtain the information such as the observation epoch time, the number of satellites, the satellite number and the corresponding pseudo-range observation; then, reading the satellite fixed coordinates at the time of signal transmission of the broadcast ephemeris calculation and taking into account the correction of the earth's rotation, fixing the known coordinates of the measuring station, calculating the real geometric distance from the satellite to the measuring station, and calculating the satellite clock error, tropospheric delay, ionospheric delay, satellite TGD, relativistic effect and other error correction values ​​according to the models such as the navigation message and the atmospheric correction, and calculating the pseudo-range calculation value according to the geometric distance and various error correction values; subtracting the pseudo-range observation value from the pseudo-range calculation value to obtain the pseudo-range observation value minus the calculation value OMC; then, based on the "median station clock elimination method", subtracting the OMC of each satellite in the same epoch from the median OMC of the epoch to obtain the single-station UERE of each satellite; finally, based on the "minimum multi-station comprehensive method", calculating the minimum absolute value of the UERE of the satellite to be monitored in all the measuring stations in the same epoch, and using the corresponding value as the final UERE monitoring result of the satellite in the epoch.

[0043] The present invention has the following advantages:

[0044] (1) The monitoring calculation of UERE involved in the prior art, such as the patent "CN114814891A A method for monitoring the integrity of a satellite navigation system", is based on the ground monitoring station of the Beidou satellite navigation system. The station clocks are strictly synchronized (i.e., the receiver clock error is 0 or accurately known), and the system monitoring stations are regionally deployed. Therefore, it is also necessary to use inter-satellite links and other means to achieve global continuous monitoring. The method of the present invention is applicable to global tracking stations whose station clocks are not synchronized (i.e., the true value of the receiver clock error is unknown), and global continuous monitoring of the navigation satellite UERE can be achieved without the use of other monitoring means.

[0045] (2) The present invention is based on the global tracking station data with asynchronous station clocks, and adopts the median method to eliminate the station clocks, thereby reducing the requirements of UERE monitoring on the synchronization of tracking station clocks, expanding the station selection conditions for UERE monitoring, and improving the station selection range, redundancy and uniformity of global monitoring, thereby realizing UERE global continuous monitoring;

[0046] (3) The present invention adopts the minimum value method for multi-station UERE comprehensive method, which greatly reduces the monitoring false alarms or missed alarms caused by the single station's own equipment, surrounding environment, local space environment or model anomalies, low altitude angle, etc., thereby improving the accuracy and reliability of UERE global continuous monitoring results. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 It is a flow chart of a navigation satellite UERE monitoring method based on multi-station asynchronous observation data;

[0048] Figure 2 This is a navigation satellite UERE monitoring method based on multi-station asynchronous observation data. Based on the "median station clock elimination method", the UERE monitoring result sequence diagram of the B1I frequency point of the Beidou PRN25 satellite at the global tracking station;

[0049] Figure 3 This is a navigation satellite UERE monitoring method based on multi-station asynchronous observation data. It is a sequence diagram of the UERE monitoring results of the B1I frequency point of the Beidou PRN25 satellite based on the "minimum multi-station comprehensive method". DETAILED DESCRIPTION

[0050] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0051] Example 1

[0052] like Figure 1 As shown in the figure, a navigation satellite UERE monitoring method based on multi-station asynchronous observation data is provided. The method is based on the pseudorange observations of global multiple redundant tracking stations with known coordinates but unsynchronized station clocks. The pseudorange observation minus the calculated value (Observed Minus Computed, OMC) is calculated using broadcast ephemeris and related error correction models, and the single-station UERE is calculated by the "median station clock elimination method". Then, the "minimum multi-station comprehensive method" is used to calculate the final UERE monitoring value, so as to realize global continuous, accurate and reliable monitoring of UERE of Beidou / GNSS and other navigation satellites. The specific steps are as follows:

[0053] Step (1) Calculation of single-station UERE based on the “median station clock elimination method”

[0054] Read the observation data of the tracking station to obtain the observation epoch time, satellite number, satellite number and corresponding pseudo-range observation information; the pseudo-range observation value obtained by the tracking station terminal r measuring the navigation signal frequency j of satellite s at a certain epoch time is It can be expressed as follows:

[0055]

[0056] In the formula, is the geometric distance between the satellite and the ground, dt r is the receiver clock error, dt s is the satellite clock error, is the tropospheric delay error, μ j is the ionospheric delay influence coefficient of frequency point j, is the ionospheric delay error corresponding to the frequency point f1, d relais the correction for relativistic effects, d r,j is the receiver code hardware delay, This is the satellite code hardware delay. is the multipath error, μ j Ionospheric delay effect coefficient;

[0057]

[0058] Step (2), based on the known coordinates of the receiver, navigation message, atmospheric correction and other models, the pseudorange calculation value can be obtained

[0059] Read the broadcast ephemeris to calculate the satellite's fixed coordinates at the time of signal transmission and take into account the earth's rotation correction. The known coordinates of the fixed station are calculated to calculate the true geometric distance from the satellite to the station. At the same time, according to the navigation message, atmospheric correction and other models, the satellite clock error, tropospheric delay, ionospheric delay, satellite TGD, relativistic effect and other error correction values ​​are calculated. The pseudorange calculation value is calculated according to the following formula

[0060]

[0061] In the formula, is the calculated value of the satellite-to-ground geometric distance, is the satellite clock error calculation value, is the calculated value of tropospheric delay error, is the calculated value of ionospheric delay error, is the calculated value corrected for relativistic effects, Calculated value of satellite code hardware delay.

[0062] Step (3) is to make a difference between the pseudorange observation value and the pseudorange calculation value, that is, to subtract equation (1) from equation (2), and obtain the pseudorange observation value minus the calculated value OMC. At this time, OMC mainly includes residual errors such as receiving clock error, pseudorange noise and multipath error, as shown in the following equation:

[0063]

[0064] In the formula, It is a comprehensive residual error including navigation message parameters, atmospheric delay correction, measurement noise and multipath errors.

[0065] Traversing all observed satellites of the epoch, obtaining the OMC value of each satellite at a certain epoch of the tracking station;

[0066] Step (4), the n satellites whose epoch terminal is r The values ​​(S = 1, 2, ..., n) are sorted from small to large, and the following sequence is obtained based on the sorting results:

[0067] OMC1≤OMC2≤…≤OMC n-1 ≤OMC n (4)

[0068] Step (5), calculate the OMC median of the OMC sequence after the epoch is sorted according to the following formula.

[0069]

[0070] Step (6), subtract the median of the OMC sequence of the epoch (which seems to be the true value of the receiver clock error) from the OMC of each satellite (such as satellite S) in the epoch according to the following formula to obtain the UERE of each satellite.

[0071] From step (3), it can be seen that the receiver clock error (including the receiver code hardware delay) has the greatest impact in OMC. However, since the tracking station is not strictly time synchronized, the receiver clock error is unknown and cannot be eliminated directly. One solution is to use the "median method" to eliminate the station clock, that is, take the median of the OMC of all satellites in the same epoch as the receiver clock error, and subtract the OMC of all satellites in the epoch from it to obtain the UERE calculated value of each satellite. Because in theory, the receiver clock error should be the same for all satellites in the same epoch, and the number of visible satellites of major GNSS systems at any location in the world is basically more than 5. Taking the GPS system as an example, its publicly released single-star integrity risk probability is 1e -5 (That is, theoretically, the total number of integrity events for the entire GPS constellation in a year does not exceed 2). Further calculations show that the probability of two or more satellites failing at the same time is about 4.98e -8 (Theoretically, it will not happen once in a hundred years) and can be ignored. Therefore, the median method ensures that the space signal of the satellite corresponding to the selected OMC median has no integrity failure, and the median's anti-gross error characteristics make it closer to the true value of the receiver clock error.

[0072]

[0073] In the formula, It represents the comprehensive residual error including navigation message parameters, atmospheric delay correction, measurement noise and multipath errors.

[0074] Traversing all tracking stations to obtain the UERE of the satellite observed by all tracking stations at the epoch time;

[0075] Step (7), final UERE calculation based on the “minimum multi-station comprehensive method”

[0076] The minimum absolute value of UERE of each satellite in all stations at the same epoch is calculated according to the following formula, and it is selected as the final UERE monitoring result of the satellite at the epoch. According to step (6), the UERE value of the satellite to be monitored at a single tracking station at a certain epoch can be obtained. In the case of global uniform multiple redundant station selection, a single satellite will be observed by multiple tracking stations at the same time, so that multiple UERE monitoring results of the satellite can be calculated at the same epoch. However, since a single station may be affected by changes in the surrounding environment of the station or signal interference, the quality of the observation data of the station may be reduced or the parameters of the received navigation message may be abnormal; and due to the influence of abnormal space environments such as active ionospheric environment and the limited accuracy of the broadcast ionosphere model, the residual error of ionospheric correction of low-altitude angle observation satellites at stations in some areas increases sharply. The above situations may lead to a situation where the satellite downlink signal is normal but the UERE monitoring result of the station is abnormal. If the UERE monitoring result of the satellite by the station is accepted at this time, it will cause a false alarm. The main purpose of considering using UERE to monitor the status of the downlink signal of the navigation satellite is to monitor whether there is an abnormality in the space signal at the satellite end, rather than to monitor the abnormalities of the user-end environment, terminal equipment and space environment. Therefore, one solution is: first sort the absolute values ​​of UERE of the satellite at multiple stations at the same epoch, and then select the UERE corresponding to the minimum absolute value in the sequence as the final UERE monitoring result of the satellite at this epoch, and then compare it with the alarm threshold or threshold to determine whether it exceeds the limit. Definition: Assuming that there are m stations observing satellite s frequency point j at the same epoch, the calculation method of UERE of satellite s frequency point j after integrating multiple stations is:

[0077]

[0078] In the formula, Min() is the minimum value function, || is the absolute value symbol;

[0079] Examples:

[0080] In order to truly and effectively reflect the UERE calculation and monitoring effect, the present invention uses the observation data of 43 global tracking stations of the International GNSS Monitoring and Assessment System (iGMAS) and the International GNSS Service Organization (IGS) on April 29, 2024. The station clocks of all tracking stations are not synchronized, and the true value of the receiver clock error is unknown. The B1I frequency point of the Beidou C25 satellite, which has a healthy satellite status and normal space signal on that day, is used as a monitoring calculation example.

[0081] like Figure 2The figure shows the UERE result sequence of each station calculated by the above global tracking station based on the “median station clock elimination method” according to steps (1) to (6) on April 29, 2024. It can be seen that under the premise that the satellite is healthy and the space signal is normal, the UERE timing variation range of each station basically reaches ±10 meters, and the short-term UERE of some stations even reaches 20 to 50 meters. This is because a single station may be affected by the surrounding environment shielding or signal interference, resulting in a decrease in the quality of observation data or even abnormalities, or local space environment abnormalities such as ionospheric scintillation and activity, abnormalities in the local area model of the broadcast ionosphere, and low altitude angles, which may cause the ionospheric correction residuals of some affected stations to increase sharply. The above situations may cause the satellite downlink signal to be normal but the UERE monitoring results of individual stations are too large or even abnormal. If the UERE monitoring results of the station are accepted at this time, it will cause false alarms.

[0082] Considering that UERE is mainly used to monitor the accuracy of satellite-side space signals (mainly broadcast orbits and clock errors) for abnormalities, rather than to monitor abnormalities in user-side environments, terminal equipment, and local space environments. Figure 2 Based on the monitoring results, the UERE monitoring results after multi-station integration are calculated according to step (7) based on the “minimum multi-station integration method”, such as Figure 3 It can be seen that under the premise that the satellite is healthy and the space signal is normal, the UERE after multi-station integration basically changes within ±2.5 meters, which can greatly reduce the monitoring errors caused by the single station's own equipment, surrounding environment, local space environment or model anomalies and low altitude angles, thereby improving the accuracy and reliability of the global continuous monitoring results of navigation satellite UERE.

[0083] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A navigation satellite UERE monitoring method based on multi-station asynchronous observation data, characterized in that: The following steps are involved: S1. Read the observation data of the tracking station to obtain the pseudo-range observation value of the navigation signal frequency j of the satellite s measured by the tracking station terminal r at a certain epoch time: S2, read the broadcast ephemeris to calculate the satellite's fixed coordinates at the time of signal transmission and perform earth rotation correction, and calculate the true geometric distance from the satellite to the measuring station based on the satellite coordinates and the known coordinates of the tracking station terminal r; According to the known coordinates of the receiver, the navigation message, and the atmospheric correction model, the satellite clock error calculation value, the tropospheric delay error calculation value, the ionospheric delay error calculation value, the relativistic effect correction calculation value, and the satellite code hardware delay calculation value are obtained; The pseudorange calculation value is obtained according to the true geometric distance from the satellite to the measuring station, the satellite clock error calculation value, the tropospheric delay error calculation value, the ionospheric delay error calculation value, the relativistic effect correction calculation value, and the satellite end code hardware delay calculation value. S3, the pseudo-range observation value The pseudorange calculated value Subtract the pseudorange observation value from the calculated value Return to step S1, and cyclically calculate the pseudo-range observation value minus the calculated value of all satellites at the same epoch time After the calculation is completed, all the pseudo-range observations minus the calculated values ​​are stored. Go to step S4; S4, tracking the n satellites whose station terminals are r at the epoch time The values ​​are sorted from small to large, S = 1, 2, ..., n, and the pseudorange observation value minus the calculated value sequence is obtained according to the sorting result: OMC1≤OMC2≤…≤OMC n-1 ≤OMC n ; S5. Calculate the OMC median Mdn(OMC) according to the pseudorange observation value minus the calculated value sequence; S6, the epoch time of each satellite Subtract the median Mdn(OMC) of the OMC sequence at the epoch to obtain the UERE of each satellite; Return to step S1, traverse all tracking station terminals r, and obtain the satellites observed by all tracking stations at the epoch time. S7. Use the minimum value multi-station comprehensive method to obtain the UERE monitoring results after multi-station comprehensive analysis Among them, Min() is the minimum value function, || is the absolute value, and m is the total number of tracking station terminals that observe satellite S; A navigation satellite UERE monitoring method based on multi-station asynchronous observation data was completed.

2. The method for monitoring UERE of a navigation satellite based on multi-station asynchronous observation data according to claim 1, characterized in that: In step S1, in, is the geometric distance between the satellite and the ground, dt r is the receiver clock error, dt s is the satellite clock error, is the tropospheric delay error, μ j is the ionospheric delay influence coefficient of frequency point j, is the ionospheric delay error, d rela is the correction for relativistic effects, d r,j is the receiver code hardware delay, This is the satellite code hardware delay. is the multipath error.

3. The method for monitoring UERE of a navigation satellite based on multi-station asynchronous observation data according to claim 2, characterized in that: Among them, f1 is the default frequency point of the ionospheric delay error calculation value.

4. The method for monitoring UERE of a navigation satellite based on multi-station asynchronous observation data according to claim 1, characterized in that: In steps S1 and S2, after reading the tracking station observation data and navigation ephemeris, the satellite PRN number and time are matched in the navigation ephemeris according to the satellite PRN number read from the observation data. After the match is successful, the satellite coordinates, satellite clock error and satellite station geometric distance are calculated. If the match is unsuccessful, the ephemeris is read continuously for matching until the ephemeris data is finished.

5. The method for monitoring UERE of a navigation satellite based on multi-station asynchronous observation data according to claim 1, characterized in that: In step S2, in, is the calculated value of the satellite-to-ground geometric distance, is the satellite clock error calculation value, is the calculated value of tropospheric delay error, is the calculated value of ionospheric delay error, is the calculated value corrected for relativistic effects, Calculated value of satellite code hardware delay.

6. The method for monitoring UERE of a navigation satellite based on multi-station asynchronous observation data according to claim 1, characterized in that: In step S3, in, is the comprehensive residual error, Including navigation message parameter errors, atmospheric delay correction residual errors, measurement noise and multipath errors.

7. The method for monitoring UERE of a navigation satellite based on asynchronous observation data of multiple stations according to claim 1, characterized in that: In step S4, first determine whether the number of satellites is greater than or equal to 2. If so, proceed If not, it cannot be solved.

8. The navigation satellite UERE monitoring method based on multi-station asynchronous observation data according to claim 1 is characterized in that: In step S5, 9. The method for monitoring UERE of a navigation satellite based on multi-station asynchronous observation data according to claim 1, characterized in that: In step S6, in, is the comprehensive residual error, Including navigation message parameter residual error, atmospheric delay correction residual error, measurement noise residual error and multipath residual error.

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