Satellite-based enhancement information generation method and system based on low-orbit constellation

Abstract

The invention discloses a satellite-based enhancement information generation method and system based on a low-orbit constellation, and relates to a satellite navigation enhancement technology, and the method comprises the steps: decoding and processing Beidou PPP-B2b message information, so as to obtain a Beidou satellite high-precision orbit and a clock error; smoothing the pseudo-range observation value by using the low-orbit satellite carrier phase observation value; constructing an ionosphere-free combined observation value by using the observation data of the low-orbit satellite, and resolving the real-time position of the low-orbit satellite based on the obtained high-precision orbit and clock correction of the Beidou satellite to obtain the position information and clock correction information of the low-orbit satellite; performing satellite-based enhanced differential correction calculation by using the obtained low-orbit satellite position information, low-orbit satellite observation data and GNSS basic navigation messages to obtain a satellite-based enhanced orbit and clock differential correction; and carrying out pseudo-range residual error correction according to the obtained satellite-based enhancement difference correction number, and carrying out satellite-based enhancement integrity parameter calculation based on a correction result. According to the method, the position of the low-orbit satellite can be determined synchronously without depending on an external high-precision GNSS satellite orbit and clock error data, and the state of the low-orbit satellite is monitored.

Description

Technical Field

[0001] The present application relates to the field of satellite navigation enhancement technology, and in particular to a method and system for generating satellite-based enhancement information based on a low-orbit constellation. Background Art

[0002] The Satellite Based Augmentation System (SBAS) uses a certain number of monitoring stations to continuously track and observe the satellites of the Global Navigation Satellite System (GNSS), and uses pseudorange, carrier phase and other observation data to process differential and integrity information, which is broadcast to users in the service area via geostationary orbit (GEO) satellites to improve the real-time positioning accuracy and integrity warning capabilities of GNSS and improve the quality of GNSS services.

[0003] Because each SBAS is independently built by each country to provide regional augmentation services, users can only obtain SBAS accuracy and integrity enhancement within the coverage of the corresponding SBAS system, which to some extent restricts the widespread application of SBAS services. Considering that low-orbit constellations can cover the world, GNSS monitoring receivers are carried on low-orbit satellites, and the GNSS observation data carried by low-orbit satellites can be used to achieve continuous differential and integrity information processing of the entire flight arc of GNSS satellites, thereby improving the service and application capabilities of SBAS.

[0004] At present, the publicly available satellite-based augmentation information processing technologies are all realized by using the observation data from a limited number of ground monitoring stations. There is still a lack of methods to realize satellite-based augmentation information processing using the GNSS observation data on low-orbit satellites.

[0005] The current satellite-based augmentation information processing technology relies on the distribution of ground monitoring stations. Once a GNSS satellite flies out of the observation range of the ground monitoring station, the satellite’s satellite-based augmentation information cannot be generated, resulting in users only being able to obtain SBAS accuracy and integrity enhancement within the coverage range of the corresponding satellite-based augmentation system. Summary of the invention

[0006] The embodiments of the present application provide a method and system for generating satellite-based augmentation information based on a low-orbit constellation, which fully utilizes the Beidou satellite's own PPP-B2b signal, does not rely on external high-precision GNSS satellite orbit and clock error data, and synchronously realizes the position determination of low-orbit satellites and monitors the status of low-orbit satellites.

[0007] The embodiment of the present application provides a method for generating satellite-based augmentation information based on a low-orbit constellation, including:

[0008] Receive PPP-B2b signals broadcast by Beidou satellites to decode and process the message information to obtain high-precision orbit and clock error of Beidou satellites;

[0009] Detect whether cycle slips occur in the low-orbit satellite observation data according to the changes in the ionospheric residual detection quantity between epochs, and, when cycle slips do not occur, smooth the pseudo-range observation values ​​using the low-orbit satellite carrier phase observation values ​​to obtain smoothed pseudo-range observation values;

[0010] Using low-orbit satellite observation data, we construct ionosphere-free combined observation values, and solve the real-time position of the low-orbit satellite based on the acquired Beidou satellite high-precision orbit and clock error to obtain the position information and clock error information of the low-orbit satellite.

[0011] Using the obtained LEO satellite position information, LEO satellite observation data and GNSS basic navigation messages, satellite-based augmentation differential corrections are calculated to obtain satellite-based augmentation orbit and clock difference corrections;

[0012] The pseudorange residual is corrected according to the obtained SBAE differential correction number, and the SBAE integrity parameters are calculated based on the correction result.

[0013] Optionally, receive the PPP-B2b signal broadcast by the Beidou satellite to decode and process the message information to obtain the Beidou satellite's real-time high-precision orbit and clock error, including:

[0014] Combine the Beidou satellite orbit correction number in the PPP-B2b message with the Beidou broadcast ephemeris orbit to recover the Beidou satellite real-time high-precision orbit:

[0015]

[0016] in, Real-time high-precision orbit of Beidou satellite, is the satellite orbit calculated by broadcast ephemeris, are the unit vectors of the orbit in radial, tangential and normal directions respectively, is the satellite orbit correction in the PPP-B2b message, δO j is the position correction number, is the velocity correction number, radial, alonge, cross are radial, tangential and normal, t is the current time, t 0 It is the reference time of Beidou PPP-B2b message;

[0017] Combine the Beidou satellite clock correction in the PPP-B2b message with the Beidou broadcast ephemeris clock error to recover the Beidou satellite real-time high-precision clock error:

[0018]

[0019] in, is the real-time clock difference of BeiDou satellite j, is the satellite clock error calculated from the broadcast ephemeris, is the satellite clock correction in the PPP-B2b message, t is the epoch time, t 0 is the BeiDou PPP-B2b message reference time, and c is the speed of light.

[0020] Optionally, the change of the ionospheric residual detection quantity between epochs is used to detect whether the low-orbit satellite observation data has a cycle slip, where the detection quantity D GF satisfy:

[0021] D GF =N 1 (t)-N 1 (t-1)-f 1 / f 2 ·[N 2 (t)-N 2 (t-1)] (3)

[0022] Among them, f 1 and f 2 is the frequency of GNSS satellite frequency points L1 and L5, N 1 and N 2 is the ambiguity of frequency points L1 and L5.

[0023] Optionally, the pseudorange observation value is smoothed using the low-orbit satellite carrier phase observation value to obtain a smoothed pseudorange observation value that satisfies:

[0024]

[0025] in, is the pseudo-range observation value after smoothing at frequency point L1, is the pseudo-range observation value after smoothing at frequency point L5, P 1 and L 1 is the original pseudorange and carrier phase observation value of frequency point L1, P 2 and L 2 are the original pseudorange and carrier phase observation values ​​of frequency point L5, and τ is the smoothing time.

[0026] Optionally, the ionosphere-free combined observation value is constructed using the low-orbit satellite observation data, and the real-time position of the low-orbit satellite is solved based on the acquired Beidou satellite real-time high-precision orbit and clock error, and the position information and clock error information of the low-orbit satellite are obtained, including:

[0027] The following ionospheric-free combined observations are constructed to eliminate the ionospheric delay error;

[0028]

[0029] Among them, PIF and L IF is the obtained ionospheric-free combined pseudorange and carrier phase observation value, and is the pseudo-range observation after smoothing at frequency points L1 and L5, L 1 and L 2 is the carrier phase observation at frequency points L1 and L5;

[0030] Using the real-time high-precision orbit and clock error of Beidou satellites and the observation data of low-orbit satellites, the real-time position of low-orbit satellites is solved to obtain the position information and clock error information of low-orbit satellites, which meets the following requirements:

[0031]

[0032] in, and is the ionosphere-free combined pseudorange and carrier phase observation value from BeiDou satellite j to low-orbit satellite i; is the geometric distance between low-orbit satellite i and Beidou satellite j, δt i ,δt j They represent the low-orbit satellite clock error and Beidou satellite real-time high-precision clock error, d error is the error that can be modeled and corrected, ε P and ε L represents the noise of pseudorange and carrier phase measurements, N j represents the integer ambiguity; λ represents the wavelength, [x i ,y i ,z i ] is the position information of low-orbit star i; [X j ,Y j ,Z j ] is the real-time high-precision orbit of Beidou satellite j.

[0033] Optionally, the satellite-based augmentation differential corrections are calculated using the obtained low-orbit satellite position information, low-orbit satellite observation data and GNSS basic navigation messages, and the satellite-based augmentation orbit and clock differential corrections are obtained, including:

[0034] Based on the inverse single point positioning principle, formula (6) is solved, where [X j ,Y j ,Z j ] is an unknown parameter, and the GNSS clock error is calculated using the clock parameters broadcast by the navigation message;

[0035] Using formula (1), the orbit correction number δO is j , Solve as an unknown parameter to obtain the satellite-based augmented orbit correction ΔO j ;

[0036] Using the satellite-based orbit correction, we can solve formula (6), where δt i is an unknown parameter; then use formula (2) to correct the clock Solve as an unknown parameter to obtain the satellite-based augmented clock differential correction ΔT j .

[0037] Optionally, the satellite-based augmentation integrity parameters are calculated according to the obtained satellite-based augmentation orbit and clock differential correction number, and the obtained satellite-based augmentation integrity parameters include:

[0038] Using the ephemeris correction ΔO j , clock correction ΔT j and the low-orbit satellite clock error δt i The corrected pseudorange residual is expressed as:

[0039]

[0040] Calculate all pseudorange residuals within one update cycle of the satellite-based augmented differential correction of GNSS satellite j The mean and standard deviation The accuracy of the satellite-based augmentation integrity parameter dual frequency ranging error (DFRE) is characterized by standard deviation, which satisfies:

[0041]

[0042] The satellite-based augmentation integrity parameter DFRE is expressed as:

[0043]

[0044] The present application also proposes a satellite-based augmentation information generation system based on a low-orbit constellation, including a processor and a memory, wherein a computer program is stored in the memory, and when the computer program is executed by the processor, the steps of the satellite-based augmentation information generation method based on the low-orbit constellation are implemented as described above.

[0045] The method of the embodiment of the present application makes full use of the PPP-B2b signal broadcast by the Beidou satellite itself, does not rely on external high-precision GNSS satellite orbit and clock error data, and synchronously realizes the position determination of low-orbit satellites and monitors the status of low-orbit satellites.

[0046] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present application. Also, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0048] Figure 1 The basic process diagram of the method for generating satellite-based augmentation information based on a low-orbit constellation according to an embodiment of the present application is shown; DETAILED DESCRIPTION

[0049] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0050] The present application embodiment provides a method for generating satellite-based augmentation information based on a low-orbit constellation, such as Figure 1 As shown, the following steps are included:

[0051] In step S101, the PPP-B2b signal broadcasted by the Beidou satellite is received, and the message information is decoded and processed to obtain the real-time high-precision orbit and clock error of the Beidou satellite. In some embodiments, a monitoring receiver carried by a low-orbit satellite can be used to receive the open and free PPP-B2b signal broadcasted by the Beidou GEO satellite in real time, and the message information is decoded and processed to obtain the real-time high-precision orbit and clock error of the Beidou satellite.

[0052] In step S102, whether cycle slips occur in the low-orbit satellite observation data is detected according to the change of the ionospheric residual detection amount between epochs, and, in the case where cycle slips do not occur, the pseudo-range observation value is smoothed using the low-orbit satellite carrier phase observation value to obtain a smoothed pseudo-range observation value. The change of the ionospheric residual detection amount between epochs can be used to detect whether cycle slips occur in the low-orbit satellite carrier phase observation data. When it is determined that there is no cycle slip, the pseudo-range observation value is smoothed using the low-orbit satellite carrier phase observation value to obtain a smoothed pseudo-range observation value.

[0053] In step S103, an ionosphere-free combined observation value is constructed for the low-orbit satellite observation data, and based on the acquired Beidou satellite real-time high-precision orbit and clock error, the real-time position of the low-orbit satellite is solved to obtain the position information and clock error information of the low-orbit satellite.

[0054] In step S104, the satellite-based augmented differential corrections are solved using the obtained low-orbit satellite position information, low-orbit satellite observation data and GNSS basic navigation messages to obtain satellite-based augmented orbit and clock differential corrections.

[0055] In step S105, pseudorange residual correction is performed according to the obtained SBAS differential correction number, and SBAS integrity parameters are calculated based on the correction result to obtain SBAS integrity parameters.

[0056] The method of the embodiment of the present application makes full use of the Beidou satellite's own PPP-B2b signal, does not rely on external high-precision GNSS satellite orbit and clock error data, and synchronously realizes the position determination of low-orbit satellites and monitors the status of low-orbit satellites.

[0057] In some embodiments, receiving a PPP-B2b signal broadcasted by a Beidou satellite to decode and process the message information to obtain a real-time high-precision orbit and clock error of the Beidou satellite includes:

[0058] Combine the Beidou satellite orbit correction number in the PPP-B2b message with the Beidou broadcast ephemeris orbit parameters to recover the Beidou satellite real-time high-precision orbit:

[0059]

[0060] in, Real-time high-precision orbit of Beidou satellite, is the satellite orbit calculated by broadcast ephemeris, are the unit vectors of the orbit in radial, tangential and normal directions respectively, is the satellite orbit correction number in the PPP-B2b message, δO j is the position correction number, is the velocity correction number, radial, alonge, cross are radial, tangential and normal, t is the current time, t 0 It is the reference time of Beidou PPP-B2b message.

[0061] Combine the Beidou satellite high-precision clock correction number in the PPP-B2b message with the Beidou broadcast ephemeris clock error parameters to recover the Beidou satellite real-time high-precision clock error:

[0062]

[0063] in, is the real-time high-precision clock error of Beidou satellite j, is the satellite clock error calculated from the broadcast ephemeris, is the satellite clock correction in the PPP-B2b message, t is the epoch time, t 0 is the BeiDou PPP-B2b message reference time, and c is the speed of light.

[0064] In some embodiments, the detection of whether the low-orbit satellite observation data has a cycle slip is performed based on the change of the ionospheric residual detection quantity between epochs, wherein the detection quantity D GF satisfy:

[0065] D GF =N 1 (t)-N 1 (t-1)-f 1 / f 2 ·[N 2 (t)-N 2 (t-1)] (3)

[0066] Among them, f 1 and f 2 is the frequency of GNSS satellite frequency points L1 and L5, N 1 and N 2 is the ambiguity of frequency points L1 and L5, and t is the epoch time.

[0067] According to the test quantity D GF When it is determined that no cycle slip occurs, in some embodiments, the pseudorange observation value is smoothed using the low-orbit satellite carrier phase observation value to obtain a smoothed pseudorange observation value that satisfies:

[0068]

[0069] in, is the pseudo-range observation value after smoothing at frequency point L1, is the pseudo-range observation value after smoothing at frequency point L5, P 1 and L 1 is the original pseudorange and carrier phase observation value of frequency point L1, P 2 and L 2 are the original pseudorange and carrier phase observation values ​​of frequency point L5, and τ is the smoothing time.

[0070] In some embodiments, an ionosphere-free combined observation value is constructed for low-orbit satellite observation data, and the real-time position of the low-orbit satellite is solved based on the acquired Beidou satellite real-time high-precision orbit and clock error, and the position information and clock error information of the low-orbit satellite are obtained, including:

[0071] The following ionospheric-free combined observations are constructed to eliminate the ionospheric delay error;

[0072]

[0073] Among them, P IF and L IF is the obtained ionospheric-free combined pseudorange and carrier phase observation value, and is the pseudo-range observation after smoothing at frequency points L1 and L5, L 1 and L 2 is the carrier phase observation at frequency points L1 and L5.

[0074] Using the real-time high-precision orbit and clock error of Beidou satellites and the ionosphere-free combined observation values, the real-time position of the low-orbit satellite is solved to obtain the position information and clock error information of the low-orbit satellite, which meets the following requirements:

[0075]

[0076] in, and is the ionosphere-free combined pseudorange and carrier phase observation value from BeiDou satellite j to low-orbit satellite i; is the geometric distance between low-orbit satellite i and Beidou satellite j, δt i ,δt j They represent the low-orbit satellite clock error and Beidou satellite real-time high-precision clock error, d error is the error that can be modeled and corrected, ε P and ε L represents the noise of pseudorange and carrier phase measurements, N j represents the integer ambiguity; λ represents the wavelength, [x i ,y i ,z i ] is the position information of low-orbit star i; [X j ,Y j ,Z j ] is the real-time high-precision orbit of Beidou satellite j.

[0077] In some embodiments, the GNSS satellite orbit is solved using the obtained low-orbit satellite position information, low-orbit satellite observation data and GNSS basic navigation messages to obtain the GNSS satellite orbit differential correction number, including:

[0078] Based on the inverse single point positioning principle, formula (6) is solved, where [X j ,Y j ,Z j ] is an unknown parameter, and the GNSS clock error is calculated using the clock parameters broadcast by the navigation message;

[0079] Using formula (1), the orbit correction number δO is j , Solve as an unknown parameter to obtain the satellite-based augmented orbit correction ΔO j ;

[0080] Using the satellite-based orbit correction, we can solve formula (6), where δt i as the unknown parameter; and then use formula (2) to correct the clock Solve as an unknown parameter to obtain the satellite-based augmented clock differential correction ΔT j .

[0081] In some embodiments, performing residual correction according to the obtained GNSS satellite orbit differential correction number includes:

[0082] Using the ephemeris correction ΔO j , clock correction ΔT j and the low-orbit satellite clock error δt i The corrected pseudorange residual is expressed as:

[0083]

[0084] Calculate all pseudorange residuals within one update cycle of satellite-based augmented differential corrections The mean and standard deviation The accuracy of the satellite-based augmentation integrity parameter dual frequency range error (DFRE) is characterized by standard deviation, which satisfies:

[0085]

[0086] The satellite-based augmentation integrity parameter DFRE is expressed as:

[0087]

[0088] The method of this application solves the problem that satellite-based augmented information processing is subject to the influence of the layout of ground monitoring stations. This application makes full use of the PPP-B2b signal broadcast by the Beidou satellite itself, and does not rely on external high-precision GNSS satellite orbit and clock error data. This application can simultaneously determine the position of low-orbit satellites and monitor the status of low-orbit satellites, and the method of this application is combined with reality and easy to implement in engineering.

[0089] The present application also proposes a satellite-based augmentation information generation system based on a low-orbit constellation, including a processor and a memory, wherein a computer program is stored in the memory, and when the computer program is executed by the processor, the steps of the satellite-based augmentation information generation method based on the low-orbit constellation are implemented as described above.

[0090] It should be noted that in the various embodiments of the present application, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "includes a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0091] The serial numbers of the above-mentioned embodiments of the present application are for description only and do not represent the advantages or disadvantages of the embodiments.

[0092] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present application, or the part that contributes to the prior art, can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, a magnetic disk, or an optical disk), and includes a number of instructions for a terminal (which can be a mobile phone, a computer, a server, an air conditioner, or a network device, etc.) to execute the methods described in each embodiment of the present application.

[0093] The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present application, ordinary technicians in this field can also make many forms without departing from the purpose of the present application and the scope of protection of the claims, all of which are within the protection of the present application.

Claims

1. A method for generating satellite-based augmentation information based on a low-orbit constellation, characterized in that: include: Receive PPP-B2b signals broadcast by Beidou satellites to decode and process the message information to obtain high-precision orbit and clock error of Beidou satellites; Detect whether cycle slips occur in the low-orbit satellite observation data according to the changes in the ionospheric residual detection quantity between epochs, and, when cycle slips do not occur, smooth the pseudo-range observation values ​​using the low-orbit satellite carrier phase observation values ​​to obtain smoothed pseudo-range observation values; Using low-orbit satellite observation data, we construct ionosphere-free combined observation values, and based on the acquired Beidou satellite high-precision orbit and clock error, we solve the real-time position of the low-orbit satellite to obtain the position information and clock error information of the low-orbit satellite. Using the obtained LEO satellite position information, LEO satellite observation data and GNSS basic navigation messages, satellite-based augmentation differential corrections are calculated to obtain satellite-based augmentation orbit and clock differential corrections; The pseudorange residual is corrected according to the obtained SBAE differential correction number, and the SBAE integrity parameters are calculated based on the correction result.

2. The method for generating satellite-based augmentation information based on a low-orbit constellation according to claim 1, characterized in that: Receive the PPP-B2b signal broadcast by Beidou satellites to decode and process the message information to obtain the real-time high-precision orbit and clock error of Beidou satellites, including: Combine the Beidou satellite orbit correction number in the PPP-B2b message with the Beidou broadcast ephemeris orbit parameters to recover the Beidou satellite real-time high-precision orbit: in, Real-time high-precision orbit of Beidou satellite, is the satellite orbit calculated by broadcast ephemeris, are the unit vectors of the orbit in radial, tangential and normal directions respectively, is the satellite orbit correction number in the PPP-B2b message, δO j is the position correction number, is the velocity correction number, radial, alonge, cross are radial, tangential and normal, t is the current time, t0 is the Beidou PPP-B2b message reference time; Combine the Beidou satellite clock correction number in the PPP-B2b message with the Beidou broadcast ephemeris clock error parameter to recover the Beidou satellite real-time high-precision clock error: in, is the real-time high-precision clock error of Beidou satellite j, is the satellite clock error calculated from the broadcast ephemeris, is the satellite clock correction number in the PPP-B2b message, t is the epoch time, t0 is the Beidou PPP-B2b message reference time, and c is the speed of light.

3. The method for generating satellite-based augmentation information based on a low-orbit constellation according to claim 1, characterized in that: According to the change of ionospheric residual detection quantity between epochs, whether the low-orbit satellite observation data has cycle slips is detected, where the detection quantity D GF satisfy: D GF =N1(t)-N1(t-1)-f1 / f2·[N2(t)-N2(t-1)] (3) Among them, f1 and f2 are the frequencies of GNSS satellite frequency points L1 and L5, and N1 and N2 are the ambiguities of frequency points L1 and L5.

4. The method for generating satellite-based augmentation information based on a low-orbit constellation according to claim 3, characterized in that: The pseudorange observations are smoothed using the low-orbit satellite carrier phase observations to obtain smoothed pseudorange observations that satisfy: in, is the pseudo-range observation value after smoothing at frequency point L1, is the smoothed pseudorange observation value of frequency point L5, P1 and L1 are the original pseudorange and carrier phase observation values ​​of frequency point L1, P2 and L2 are the original pseudorange and carrier phase observation values ​​of frequency point L5, and τ is the smoothing time.

5. The method for generating satellite-based augmentation information based on a low-orbit constellation according to claim 4, characterized in that: Using the observation data of low-orbit satellites, the ionosphere-free combined observation value is constructed, and the position of the low-orbit satellite is solved based on the real-time high-precision orbit and clock error of the Beidou satellite. The position information and clock error information of the low-orbit satellite are obtained, including: The following ionospheric-free combined observations are constructed to eliminate the ionospheric delay error; Among them, P IF and L IF is the obtained ionospheric-free combined pseudorange and carrier phase observation value, and is the pseudo-range observation after smoothing at the frequency points L1 and L5, L1 and L2 are the carrier phase observations at the frequency points L1 and L5; Using the real-time high-precision orbit and clock error of Beidou satellites and the ionosphere-free combined observation values, the real-time position of the low-orbit satellite is solved to obtain the position information and clock error information of the low-orbit satellite, which meets the following requirements: in, and is the ionosphere-free combined pseudorange and carrier phase observation value from BeiDou satellite j to low-orbit satellite i; is the geometric distance between low-orbit satellite i and Beidou satellite j, δt i ,δt j They represent the low-orbit satellite clock error and Beidou satellite real-time high-precision clock error, d error is the error that can be modeled and corrected, ε P and ε L represents the noise of pseudorange and carrier phase measurements, N j represents the integer ambiguity; λ represents the wavelength, [x i ,y i ,z i ] is the position information of low-orbit star i; [X j ,Y j ,Z j ] is the real-time high-precision orbit of Beidou satellite j.

6. The method for generating satellite-based augmentation information based on a low-orbit constellation according to claim 5, characterized in that: Using the obtained low-orbit satellite position information, low-orbit satellite observation data and GNSS basic navigation messages, the GNSS satellite orbit is solved to obtain the satellite-based augmented orbit differential correction number, including: Based on the inverse point positioning principle, formula (6) is solved, where the real-time high-precision orbit of Beidou satellite j [X j ,Y j ,Z j ] is an unknown parameter, and the GNSS clock error is calculated using the clock parameters broadcast by the navigation message; Using formula (1), the orbit correction number δO is j , Solve as an unknown parameter to obtain the satellite-based enhanced orbit differential correction ΔO j ; Using the satellite-based orbit correction, we can solve formula (6), where δt i as the unknown parameter; and then use formula (2) to correct the clock Solve as an unknown parameter to obtain the satellite-based augmented clock differential correction ΔT j .

7. The method for generating satellite-based augmentation information based on a low-orbit constellation according to claim 6, characterized in that: The satellite-based augmentation integrity parameters are calculated based on the obtained satellite-based augmentation orbit and clock differential correction numbers, and the satellite-based augmentation integrity parameters obtained include: Using the ephemeris correction ΔO j , clock correction ΔT j and the low-orbit satellite clock error δt i The corrected pseudorange residual is expressed as: Calculate the total pseudorange residual ΔP within one update cycle of the satellite-based augmented differential correction i j The mean and standard deviation The accuracy of the satellite-based augmentation integrity parameter dual frequency range error (DFRE) is characterized by standard deviation, which satisfies: The satellite-based augmentation integrity parameter DFRE is expressed as:

8. A satellite-based augmentation information generation system based on a low-orbit constellation, characterized in that: It comprises a processor and a memory, wherein a computer program is stored in the memory, and when the computer program is executed by the processor, the steps of the method for generating satellite-based augmentation information based on a low-orbit constellation are implemented as described in any one of claims 1 to 7.

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