System and method for upgrading radio beacon differential station and being compatible with Beidou No.3

Abstract

The invention relates to the technical field of radio beacon differential stations, in particular to a system and method for upgrading a radio beacon differential station to be compatible with Beidou No.3. The system comprises a base station broadcasting station and an integrity monitoring station; the base station broadcasting station comprises a GNSS antenna, an RS base station, an RS server, an MSK modulator and a transmitter; the integrity monitoring station comprises a GNSS antenna, a beacon antenna, an IM integrity monitoring receiver and an IM server; by upgrading a GNSS board card and a differential generation algorithm of a base station receiver and a GNSS board card and a differential calculation algorithm of a perfect monitoring station receiver, receiving and calculation of Beidou No.3 navigation messages B1C and B2a signals are realized, and the system and the method are compatible with the Beidou No.3 navigation messages by upgrading the GNSS board card and the differential generation algorithm of the base station receiver and the GNSS board card and the differential calculation algorithm of the perfect monitoring station receiver. The problem that a radio beacon differential station is not compatible with a Beidou third-generation satellite system is solved, and feasible technical guidance and application schemes are provided for follow-up engineering practical application.

Description

Technical Field

[0001] The present invention relates to the technical field of radio beacon differential stations, and in particular to a system and method for upgrading a radio beacon differential station to be compatible with BeiDou-3. Background Art

[0002] As of 2019, my country's coastal radio beacon differential station system has completed the BeiDou dual-mode transformation project in two phases, realizing the dual-mode co-frequency broadcast of differential BeiDou and differential GPS, improving the system positioning accuracy and signal availability, and promoting the in-depth application of my country's independent BeiDou system in the field of navigation support. In 2020, the BeiDou-3 system was completed and provided services to the world. Compared with the BeiDou-2 system, the BeiDou-3 system added a new signal system, optimized the design of navigation messages, and further improved the accuracy of space signals. At the same time, the BeiDou-3 system uses a satellite-borne hydrogen atomic clock, which has increased its accuracy by an order of magnitude, thereby improving the accuracy of timing and time synchronization.

[0003] With the full opening of the BeiDou-3 system, conditions have been created for the upgrade of coastal radio beacon differential station systems to support the broadcasting of BeiDou-3 navigation messages. Upgrading to be compatible with BeiDou-3 navigation messages can, on the one hand, make full use of the main signals of the BeiDou-3 system and improve the utilization rate of differential positioning by future users; on the other hand, it can make full use of the high-orbit satellites of the BeiDou system's space segment hybrid constellation to provide DGNSS users in coastal low-latitude areas with stronger satellite positioning signal coverage and anti-obstruction capabilities, further improving the service efficiency and safety of coastal radio beacon differential station systems.

[0004] Qingdao Wangjiamai RBN / DGNSS station completed the Beidou and GPS dual-mode transformation in 2017, and realized the compatible broadcasting of differential GPS and differential BDS signals. At present, Wangjiamai RBN / DGNSS station adopts CATON9001 series RBN-DGNSS system, and the main equipment includes base station, integrity monitoring station, medium wave transmitter, industrial computer and supporting BSC software. It currently supports the reception and solution of Beidou-2 B1I, B2I and B3I navigation messages.

[0005] At the same time, the China Satellite Navigation System Management Office has also released the signal characteristics, navigation message structure and user algorithm of the public service signals B1C and B2a between the Beidou satellite navigation system space constellation and user terminals in 2020. This has fully met the implementation conditions for the RBN-DGNSS station to upgrade and be compatible with the Beidou-3 navigation message.

[0006] As the BeiDou-3 system provides services worldwide, the system has inherited and retained the B1I and B3I signals of the BeiDou-2 satellite, added the B1C public signal, upgraded the B2 signal, and replaced the original B2I signal with the newly designed B2a signal, thus improving the signal performance. As the main signal types of the future BeiDou navigation system, B1C and B2a are of great significance and value to be incorporated into the RBN-DGNSS coastal radio beacon differential station system of the ground-based augmentation system. Based on this practical need, it is necessary to carry out preliminary research and application verification work. By upgrading the current system's GNSS satellite receiving module, soft differential algorithm, standard protocol and other software and hardware modules, the system can be better integrated with the BeiDou satellite navigation system to serve coastal users.

[0007] At present, the radio beacon differential stations along the coast of the country are not compatible with the BeiDou-3 satellite system. Therefore, in view of the above situation, there is an urgent need to develop a system and method for upgrading radio beacon differential stations to be compatible with BeiDou-3 in order to overcome the shortcomings in current practical applications. Summary of the invention

[0008] The object of the present invention is to provide a system and method for upgrading a radio beacon differential station to be compatible with BeiDou-3, so as to solve the problems raised in the above-mentioned background technology.

[0009] To achieve the above object, the present invention provides the following technical solutions:

[0010] A system for upgrading a radio beacon differential station to be compatible with BeiDou-3, including a base station broadcasting station and a completeness monitoring station;

[0011] The base station broadcast station includes a GNSS antenna, an RS base station, an RS server, an MSK modulator and a transmitter; the integrity monitoring station includes a GNSS antenna, a beacon antenna, an IM integrity monitoring receiver and an IM server;

[0012] By upgrading the GNSS board and differential generation algorithm of the base station receiver and improving the GNSS board and differential decomposition algorithm of the monitoring station receiver, the reception and resolution of the BeiDou-3 navigation message B1C and B2a signals can be achieved.

[0013] As a further solution of the present invention: the differential generation algorithm is used to decode the satellite raw data stream received by the GNSS navigation satellite receiver in real time, calculate the pseudorange correction number, and package the pseudorange correction number into a standard RTCM2.X format message for broadcasting.

[0014] As a further solution of the present invention: the differential decomposition algorithm is used to decode the satellite raw data stream received by the GNSS satellite navigation receiver in real time, receive the RTCM2.X pseudorange correction message, decode the pseudorange correction message, and use the differential correction number to correct the observation value to complete the positioning solution.

[0015] As a further solution of the present invention: the algorithm also includes altitude angle weighting, anti-error algorithm and hybrid weighting model algorithm to improve positioning accuracy and stability.

[0016] As a further solution of the present invention: the hybrid weight determination model algorithm comprehensively considers the influence of the altitude angle and the signal-to-noise ratio, and adopts a hybrid model for weight determination.

[0017] A method for upgrading a radio beacon differential station to be compatible with BeiDou-3 adopts the system for upgrading a radio beacon differential station to be compatible with BeiDou-3 as described above, including upgrading the GNSS board and differential generation algorithm of a base station receiver and the GNSS board and differential resolution algorithm of a integrity monitoring station receiver on the basis of the original station, so as to realize the reception and resolution of BeiDou-3 navigation message B1C and B2a signals.

[0018] As a further solution of the present invention: the execution steps of the differential generation algorithm include: real-time decoding of the satellite raw data stream received by the GNSS navigation satellite receiver, calculating the pseudorange correction number, and packaging the pseudorange correction number into a standard RTCM2.X format message for broadcasting.

[0019] As a further solution of the present invention: the execution steps of the differential decomposition algorithm include: real-time decoding of the satellite raw data stream received by the GNSS satellite navigation receiver, receiving the RTCM2.X pseudorange correction message, decoding the pseudorange correction message, and using the differential correction number to correct the observation value to complete the positioning solution.

[0020] As a further solution of the present invention: when executing the differential generation algorithm or the differential decomposition algorithm, it also includes adopting the altitude angle weighting, the anti-error algorithm and the hybrid weighting model algorithm to improve the positioning accuracy and stability.

[0021] As a further solution of the present invention: the execution step of the hybrid weight determination model algorithm includes: comprehensively considering the influence of the altitude angle and the signal-to-noise ratio, and using the hybrid model for weight determination.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. This application can be used for coastal RBN-DGNSS station systems and ship-borne terminals with DGNSS functions. It can gradually upgrade China's coastal RBN-DGNSS station systems to be fully compatible with the reception and resolution of BeiDou-3 navigation messages, and gradually upgrade existing ship-borne DGNSS positioning terminals to enable ship-borne DGNSS positioning terminals to have the ability to receive and resolve BeiDou-3 navigation messages, which can be applied to the promotion and use of China's coastal RBN-DGNSS station systems. It solves the problem that the current national coastal radio beacon differential stations are not compatible with the BeiDou-3 satellite system, and provides feasible technical guidance and application solutions for subsequent engineering practice applications;

[0024] 2. This application has developed a differential generation algorithm and a differential resolution algorithm that support the BeiDou-3 satellite system. The algorithm adopts the design concept of software radio and can be deployed on a general server to run. It collects satellite ephemeris data and original observation data output by the GNSS module to perform data calculations and solutions. On the basis of being compatible with the original station broadcast signals, the algorithm adds data solutions for the BeiDou-3 main push signals B1C and B2a. At the same time, after adding the observation signal type, under the conditions of a significant increase in satellite observations and a limited station MSK modulation rate of 200bps, the broadcasting method, information content and quantity of pseudo-range differential data are optimized to meet the performance indicators required by the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a diagram of the station architecture after upgrading to be compatible with BeiDou-3 in an embodiment of the present invention.

[0026] Figure 2 4 is a flowchart of the reference station algorithm processing in an embodiment of the present invention.

[0027] Figure 3 1 is a flowchart of the differential decomposition algorithm processing in an embodiment of the present invention. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] The specific implementation of the present invention is described in detail below in conjunction with specific embodiments.

[0030] See also Figure 1-Figure 3 , a radio beacon differential station upgrade compatible with BeiDou-3 system provided by an embodiment of the present invention includes a reference station broadcasting station and a completeness monitoring station;

[0031] The base station broadcast station includes a GNSS antenna, an RS base station, an RS server, an MSK modulator and a transmitter; the integrity monitoring station includes a GNSS antenna, a beacon antenna, an IM integrity monitoring receiver and an IM server;

[0032] By upgrading the GNSS board and differential generation algorithm of the base station receiver and improving the GNSS board and differential decomposition algorithm of the monitoring station receiver, the reception and resolution of the BeiDou-3 navigation message B1C and B2a signals can be achieved.

[0033] The differential generation algorithm is used to decode the satellite raw data stream received by the GNSS navigation satellite receiver in real time, calculate the pseudorange correction number, and package the pseudorange correction number into a standard RTCM2.X format message for broadcasting.

[0034] The differential decomposition algorithm is used to decode the satellite raw data stream received by the GNSS satellite navigation receiver in real time, receive the RTCM2.X pseudorange correction message, decode the pseudorange correction message, and use the differential correction number to correct the observation value to complete the positioning solution.

[0035] The algorithm also includes altitude angle weighting, anti-error algorithm and hybrid weighting model algorithm to improve positioning accuracy and stability.

[0036] The hybrid weight determination model algorithm comprehensively considers the influence of the altitude angle and the signal-to-noise ratio, and adopts a hybrid model for weight determination.

[0037] The system for upgrading the radio beacon differential station to be compatible with BeiDou-3 in this application consists of a base station broadcast station and an integrity monitoring station. The broadcast station includes a GNSS antenna, an RS base station, an RS server, an MSK modulator and a transmitter, and the integrity monitoring station includes a GNSS antenna, a beacon antenna, an IM integrity monitoring receiver and an IM server, etc. Figure 1 shown.

[0038] In the process of researching and applying the key technologies for the upgrade of radio beacon differential stations to be compatible with BeiDou-3, the overall technical route of the research is to complete the upgrade and transformation work on the basis of the original station while keeping the original station architecture, software and hardware interfaces, and communication protocols unchanged as much as possible. The yellow part is the software module and hardware module upgraded in this study. In the station reference station part, the base station receiver GNSS board and differential generation algorithm are upgraded; in the integrity monitoring station part, the monitoring station receiver GNSS board and differential decomposition algorithm are upgraded, and finally the station is compatible with BeiDou-3. The BeiDou system types that can be broadcast include B1I / B2I / B3I / B1C / B2a.

[0039] This application can be used for coastal RBN-DGNSS station systems and ship-borne terminals with DGNSS functions, and can gradually upgrade China's coastal RBN-DGNSS station systems to be fully compatible with the reception and resolution of BeiDou-3 navigation messages, and gradually upgrade existing ship-borne DGNSS positioning terminals, so that ship-borne DGNSS positioning terminals have the ability to receive and resolve BeiDou-3 navigation messages, and can be applied to the promotion and use of China's coastal RBN-DGNSS station systems. It solves the problem that the current national coastal radio beacon differential stations are not compatible with the BeiDou-3 satellite system, and provides feasible technical guidance and application solutions for subsequent engineering practice applications.

[0040] A method for upgrading a radio beacon differential station to be compatible with BeiDou-3 adopts the above-mentioned system for upgrading a radio beacon differential station to be compatible with BeiDou-3, including upgrading the GNSS board and differential generation algorithm of a base station receiver and the GNSS board and differential resolution algorithm of a integrity monitoring station receiver on the basis of the original station, so as to realize the reception and resolution of BeiDou-3 navigation message B1C and B2a signals.

[0041] The execution steps of the differential generation algorithm include: real-time decoding of the satellite raw data stream received by the GNSS navigation satellite receiver, calculating the pseudo-range correction number, and packaging the pseudo-range correction number into a standard RTCM2.X format message for broadcasting.

[0042] The execution steps of the differential solution algorithm include: real-time decoding of the satellite raw data stream received by the GNSS satellite navigation receiver, receiving the RTCM2.X pseudo-range correction message, decoding the pseudo-range correction message, and using the differential correction number to correct the observation value to complete the positioning solution.

[0043] When executing the differential generation algorithm or the differential decomposition algorithm, it also includes adopting the altitude angle weighting, the anti-error algorithm and the hybrid weighting model algorithm to improve the positioning accuracy and stability.

[0044] The execution steps of the hybrid weight determination model algorithm include: comprehensively considering the influence of the altitude angle and the signal-to-noise ratio, and using the hybrid model to determine the weight.

[0045] The following is a detailed description of the key technologies and algorithms, as follows:

[0046] B1C and B2a signals are public service signals, and the relevant signal interface standard documents have been made public. The algorithm, based on the reception of the original signals, adds the reception of the original observation data of the B1C and B2a signals according to the standards. Based on the premise that the base station coordinates are known, the pseudorange correction number can be calculated. The correction number includes errors caused by the ionosphere, troposphere, satellite clock, multipath, etc. The mobile station can correct these errors in real time and perform positioning solutions with higher accuracy than single-point positioning.

[0047] The original observation equation of pseudorange:

[0048] but:

[0049] Since the base station coordinates are known, the satellite-to-ground distance It can be accurately obtained, and then the receiver clock error is obtained by using the least square method with base station coordinate constraints. The satellite clock error can be calculated from the satellite ephemeris. Using the above formula, the pseudorange correction number can be obtained.

[0050] Where: Pseudorange observations, Residual, Ionospheric delay, Tropospheric delay, Multipath effect, C: speed of light, t: time, PRC: pseudorange value.

[0051] After obtaining the pseudorange correction number, the pseudorange can be corrected directly. The troposphere and ionosphere values ​​no longer need to be obtained through model values. Compared with the model value, the pseudorange correction number (PRC) can better reflect the current error situation, so the positioning solution can obtain higher accuracy. The basic equation is:

[0052]

[0053] After obtaining higher-precision pseudorange observation values, the least squares method can be used to solve and obtain higher-precision coordinate values.

[0054] like Figure 2 As shown in the figure, the algorithm processing flow of the RS base station (differential generation algorithm) is as follows: the differential generation algorithm mainly completes the real-time decoding of the satellite raw data stream received by the GNSS navigation satellite receiver, and calculates the pseudo-range correction number based on the decoded observation value and ephemeris data according to the constructed algorithm model. The correction number includes errors caused by the ionosphere, troposphere, satellite clock, multipath, etc., and uses the known coordinates of the base station to package the above error values ​​into a standard RTCM2.X format message, that is, the pseudo-range correction number, and broadcast it.

[0055] like Figure 3As shown in the figure, the algorithm processing flow of the IM integrity monitoring station or mobile station (differential decomposition algorithm): The differential decomposition algorithm mainly completes the real-time decoding of the satellite raw data stream received by the GNSS satellite navigation receiver, and the decoded observation values ​​and ephemeris data are used according to the constructed algorithm model to perform single-point positioning calculation. At the same time, the RTCM2.X pseudo-range correction message is received in real time, and the pseudo-range correction message is decoded. If it is a grouped message, the independent satellite data of the epoch of nearly 30 seconds are collected and cached for combination. If not, the data of the latest epoch is used. At the same time, it is determined whether the data age exceeds the limit. If it does not exceed the limit, the observation value is corrected using the differential correction number to complete the RTD positioning, and the positioning result is Kalman filtered to output the final positioning result.

[0056] Among them, the single point positioning algorithm is as follows:

[0057]

[0058] Linearization:

[0059]

[0060] Where: is the pseudorange observation value at time Ti, is the residual, For the distance between the guard and the ground, is the ionospheric delay, is the tropospheric delay, t i (T i ) is the receiver clock error, is the multipath effect, t k (T i ) satellite clock error, is the radial velocity, ε(T i ) are other errors, Z, Y, Z are the spatial coordinate system, and C is the speed of light.

[0061] Among them, ionospheric delay and satellite clock error can be corrected by the model, and the radial motion distance of the satellite relative to the receiver can be accurately determined to the millimeter level by the radial velocity of the satellite relative to the receiver calculated by the satellite ephemeris and the receiver clock error calculated by the pseudo-range single point positioning. Multipath error is usually ignored. These items are grouped into one item, namely:

[0062]

[0063] Tropospheric delay can be calculated by i (T i ) is projected to the tilt direction through the projection function, that is:

[0064]

[0065] The simplified non-difference mathematical model is:

[0066]

[0067] The RTD base station algorithm uses the premise that the base station coordinates are known to calculate the pseudorange correction number. The correction number includes errors caused by the ionosphere, troposphere, satellite clock and multipath. The mobile station corrects these errors in real time and can perform positioning solutions with higher accuracy than single-point positioning.

[0068] Simplify the original observation equation of pseudorange:

[0069]

[0070] but:

[0071]

[0072] Since the base station coordinates are known, the satellite-to-ground distance It can be accurately obtained, and then the receiver clock error is obtained by the least square method with base station coordinate constraints. The satellite clock error can be calculated from the satellite ephemeris. Using the above formula, the pseudorange correction number can be obtained.

[0073] After obtaining the pseudorange correction number, the mobile station can directly correct the pseudorange. The troposphere and ionosphere values ​​no longer need to be obtained through model values. Compared with the model value, the pseudorange correction number (PRC) can better reflect the current error situation, so the positioning solution can obtain higher accuracy. The basic equation is:

[0074]

[0075] After obtaining higher-precision pseudorange observations, the least squares method can be used to solve and obtain higher-precision coordinate values; where: P is the pseudorange observation, V is the residual, p is the distance between the satellite and the ground, C is the speed of light, and PRC is the pseudorange correction number.

[0076] In positioning solution, in order to ensure the accuracy of positioning, different satellite observation values ​​must be weighted. The quality of satellite observation values ​​is generally positively correlated with the altitude angle, because the higher the altitude angle, the less interference is received. In both base station and mobile station algorithms, altitude angle weighting is used to obtain the optimal positioning results.

[0077] The trigonometric function height angle weighting formula is:

[0078] P = 1 / (cos(ele)*cos(ele));

[0079] Among them: ele is the altitude angle, P is the altitude angle weight.

[0080] It is very common for observation values ​​to be affected by gross errors. In both base station algorithms and mobile station algorithms, anti-error algorithms are used to obtain stable positioning results.

[0081] The robustness algorithm used in the algorithm is a three-segment weight function:

[0082]

[0083] in, is the normalized residual, K0=1.0~1.5 and K1=2.5~8.0 are constants.

[0084] With the correction numbers of BeiDou 3 multi-frequency data, when positioning at the mobile station, a suitable random model should be selected for solution. The existing random models include equal-weight model, altitude angle model and signal-to-noise ratio model. A single indicator is difficult to meet the high-precision positioning and navigation of the entire scene. The altitude angle model can effectively weaken the atmospheric residual error, but the weakening effect on the derivative error is not obvious. The SNR model can eliminate the influence of the derivative error very well, but the sensitivity to the atmospheric error is not as good as the altitude angle model. Therefore, this application comprehensively considers the influence of altitude angle and signal-to-noise ratio to maximize the benefits of BeiDou 3 multi-frequency data.

[0085] Altitude Angle Model:

[0086]

[0087] Where E is the altitude angle, and a and b are empirical values.

[0088] Signal-to-Noise Ratio Model:

[0089]

[0090] In the above formula, C / N0 is the signal-to-noise ratio, and a and b are empirical values.

[0091] This paper comprehensively considers the altitude angle and signal-to-noise ratio and adopts the following hybrid model:

[0092] δ 2 =w ele δ ele 2 +w snr δ snr 2 ;

[0093] where w ele is the weight of the altitude angle model, w snr is the weight of the signal-to-noise ratio model, satisfying w ele +w snr =1.

[0094] Expanded:

[0095]

[0096] The above model comprehensively considers the influence of SNR and altitude angle. In complex scenarios, it can better suppress jump points and is more accurate than the weighting of a single SNR model and altitude angle model.

[0097] Since the accuracy of carrier phase observations is almost two orders of magnitude higher than that of pseudorange observations, carrier phase observations are often used to smooth pseudoranges to improve the ranging accuracy of pseudoranges. However, the premise of using carrier phase is to accurately identify cycle slips to avoid errors. Beidou 3 multi-frequency data can greatly improve the accuracy of cycle slip detection.

[0098] In 1986, American scholar Goad proposed to use the ionospheric residual measured by dual-frequency carrier phase to detect and repair cycle slips, which is called the ionospheric residual method. When the ionosphere is relatively stable, the sampling interval is short (a few seconds), and the change of ionospheric delay is sub-centimeter level, if the ionospheric residual changes suddenly between two adjacent epochs, it means that the carrier phase observation value of L1 or L2 may have a cycle slip.

[0099] The ionospheric residual combined observation equation can be obtained by linearly combining the carrier phase observation equations on the L1 and L2 frequency bands:

[0100]

[0101] Where C is the speed of light, f1 and f2 are the original carrier frequencies, N1 and N2 are the original carrier integer ambiguities, and The original carrier phase observation, A is a constant.

[0102] The Beidou three satellite signals tracked by the GNSS receiver include B1I / B3I / B1c / B2a, which can realize multiple ionospheric residual combinations to detect and analyze cycle slips respectively, thereby improving the reliability of detection. By analyzing the frequencies between each frequency point, four ionospheric residual combinations are formed: B1I / B3I, B1I / B2a, B1c / B2a, B1c / B3I. It can be found that each frequency point is involved in two groups of ionospheric residual combinations. If both groups detect cycle slips, the frequency point is very likely to have a cycle slip and needs to be marked. If only one of the combinations has a cycle slip, and the other combination has not, the value of the cycle slip combination is further judged. If it only exceeds the threshold a little, it can be considered that no actual cycle slip has occurred. After accurately determining the cycle slip of each satellite, the phase smoothing pseudorange can be further used to further smooth the pseudorange value to improve the average positioning performance.

[0103] Therefore, in summary, this application has developed a differential generation algorithm and a differential decomposition algorithm that support the BeiDou-3 satellite system. The algorithm adopts the design concept of software radio and can be deployed on a general server to run. It collects satellite ephemeris data and original observation data output by the GNSS module to perform data calculations and solutions. On the basis of being compatible with the original station broadcast signals, the algorithm adds the data solution of the BeiDou-3 main push signals B1C and B2a. At the same time, after increasing the type of observation signals, under the conditions of a significant increase in satellite observations and a limited station MSK modulation rate of 200bps, the broadcasting method, information content and quantity of pseudo-range differential data are optimized to meet the performance indicators required by the system.

[0104] It should be noted that in the present invention, it should be understood that although this specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that those skilled in the art can understand.

Claims

1. A system for upgrading a radio beacon differential station to be compatible with BeiDou-3, characterized in that: Includes base station broadcasting station and integrity monitoring station; The base station broadcast station includes a GNSS antenna, an RS base station, an RS server, an MSK modulator and a transmitter; the integrity monitoring station includes a GNSS antenna, a beacon antenna, an IM integrity monitoring receiver and an IM server; By upgrading the GNSS board and differential generation algorithm of the base station receiver and improving the GNSS board and differential decomposition algorithm of the monitoring station receiver, the reception and resolution of the BeiDou-3 navigation message B1C and B2a signals can be achieved.

2. The system for upgrading the radio beacon differential station to be compatible with BeiDou-3 according to claim 1, characterized in that: The differential generation algorithm is used to decode the satellite raw data stream received by the GNSS navigation satellite receiver in real time, calculate the pseudorange correction number, and package the pseudorange correction number into a standard RTCM2.X format message for broadcasting.

3. The system for upgrading the radio beacon differential station to be compatible with BeiDou-3 according to claim 1, characterized in that: The differential decomposition algorithm is used to decode the satellite raw data stream received by the GNSS satellite navigation receiver in real time, receive the RTCM2.X pseudorange correction message, decode the pseudorange correction message, and use the differential correction number to correct the observation value to complete the positioning solution.

4. The system for upgrading the radio beacon differential station to be compatible with BeiDou-3 according to claim 1, characterized in that: The algorithm also includes altitude angle weighting, anti-error algorithm and hybrid weighting model algorithm to improve positioning accuracy and stability.

5. The system for upgrading the radio beacon differential station to be compatible with BeiDou-3 according to claim 4, characterized in that: The hybrid weight determination model algorithm comprehensively considers the influence of the altitude angle and the signal-to-noise ratio, and adopts a hybrid model for weight determination.

6. A method for upgrading a radio beacon differential station to be compatible with BeiDou-3, using the system for upgrading a radio beacon differential station to be compatible with BeiDou-3 as claimed in any one of claims 1 to 5, characterized in that: This includes upgrading the GNSS board and differential generation algorithm of the base station receiver and the GNSS board and differential decomposition algorithm of the integrity monitoring station receiver based on the original stations, so as to realize the reception and decomposition of the Beidou-3 navigation message B1C and B2a signals.

7. The method for upgrading the radio beacon differential station to be compatible with BeiDou-3 according to claim 6, characterized in that: The execution steps of the differential generation algorithm include: real-time decoding of the satellite raw data stream received by the GNSS navigation satellite receiver, calculating the pseudo-range correction number, and packaging the pseudo-range correction number into a standard RTCM2.X format message for broadcasting.

8. The method for upgrading a radio beacon differential station to be compatible with BeiDou-3 according to claim 6, characterized in that: The execution steps of the differential solution algorithm include: real-time decoding of the satellite raw data stream received by the GNSS satellite navigation receiver, receiving the RTCM2.X pseudo-range correction message, decoding the pseudo-range correction message, and using the differential correction number to correct the observation value to complete the positioning solution.

9. The method for upgrading a radio beacon differential station to be compatible with BeiDou-3 according to claim 6, characterized in that: When executing the differential generation algorithm or the differential decomposition algorithm, it also includes adopting the altitude angle weighting, the anti-error algorithm and the hybrid weighting model algorithm to improve the positioning accuracy and stability.

10. The method for upgrading a radio beacon differential station to be compatible with BeiDou-3 according to claim 9, characterized in that: The execution steps of the hybrid weight determination model algorithm include: comprehensively considering the influence of the altitude angle and the signal-to-noise ratio, and using the hybrid model to determine the weight.

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