Single Beidou global precision time service method and system based on broadcast ephemeris

Abstract

The invention discloses a single Beidou global precision time service method and system based on broadcast ephemeris, and the method comprises the steps: obtaining broadcast ephemeris data and satellite observation data transmitted by a Beidou satellite, and carrying out the analysis, and obtaining a real-time satellite orbit and a real-time satellite clock error; calculating an actual spatial distance error value of last time service of the broadcast ephemeris according to difference values between the real-time satellite orbit and the real-time satellite clock difference and a Beidou satellite precision product published by international GNSS service, and estimating an estimated spatial distance error value of the time service according to the actual spatial distance error value of the last time service; the satellite observation data and the space distance error estimation value are substituted into a broadcast ephemeris single Beidou PPP time service model based on the space distance error, and the receiver clock error is corrected; and carrying out clock taming according to the corrected receiver clock difference, and sending a tamed clock signal to the Beidou satellite receiver, so that the Beidou satellite receiver outputs corrected time information, and precise time service is completed. The method is higher in precision and better in stability.

Description

Technical Field

[0001] The present invention relates to satellite timing technology, and in particular to a single Beidou global precise timing method and system based on broadcast ephemeris. Background Art

[0002] Satellite timing technology has become a leader in the timing industry with its high precision and wide application fields, covering many important fields such as electricity, finance, smart transportation, smart life, Internet of Things, 5G communication and military. However, with the advancement of science and technology, traditional satellite timing methods - which rely on broadcast ephemeris and have an accuracy of 20 to 50 nanoseconds - have begun to fail to meet the needs of the high-precision technology industry. In order to improve the accuracy of timing, high-precision technologies such as common-view satellite timing, full-view satellite timing and precise point positioning (PPP) timing are currently used. Among these methods, PPP timing has the highest accuracy, but they all require network communication to achieve data exchange, which makes it difficult to guarantee the needs of time services in various environments. Therefore, traditional satellite timing technology seems to be unable to meet the high-precision technology needs in different environments. The successful networking of the Beidou-3 (BDS-3) global satellite navigation system has provided new possibilities for high-precision timing services. Using the broadcast ephemeris and observation values ​​of Beidou-3, combined with the PPP timing method, users can directly receive these data and achieve high-precision global timing without relying on network communication. This progress meets the needs of global users for high-precision time services and brings new solutions to the high-precision technology industry. However, the timing accuracy of the current timing method still needs to be improved. Summary of the invention

[0003] In view of the problems existing in the prior art, the purpose of the present invention is to provide a single Beidou global precise timing method, device and system based on broadcast ephemeris with higher timing accuracy.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0005] A single Beidou global precise timing method based on broadcast ephemeris comprises the following steps:

[0006] (1) Obtain the broadcast ephemeris data and satellite observation data sent by Beidou satellites, and parse the broadcast ephemeris data to obtain real-time satellite orbits and real-time satellite clock errors;

[0007] (2) Based on the differences between the real-time satellite orbit and real-time satellite clock error and the Beidou satellite precision products released by the international GNSS service, the actual value of the spatial distance error of the last broadcast ephemeris time is calculated, and based on the actual value of the spatial distance error, the Allan variance of the spatial distance error is estimated;

[0008] (3) Estimate the spatial distance error based on the Allan variance of the spatial distance error to obtain the estimated value of the spatial distance error for this timing;

[0009] (4) Establish a single Beidou PPP timing model based on broadcast ephemeris and spatial distance error;

[0010] (5) Substitute the satellite observation data and the estimated value of the spatial distance error into the broadcast ephemeris single Beidou PPP timing model and solve the model to obtain the corrected receiver clock error;

[0011] (6) Perform clock training based on the corrected receiver clock error, and send the trained clock signal to the Beidou satellite receiver, so that the Beidou satellite receiver outputs the corrected time information and completes precise timing.

[0012] Furthermore, step (2) specifically includes:

[0013] (2-1) Subtract the real-time satellite orbit from the precise satellite orbit of the Beidou satellite precision product, and use the difference as the real-time precise orbit difference; subtract the real-time satellite clock error from the precise satellite clock error of the Beidou satellite precision product, and use the difference as the real-time precise clock error difference;

[0014] (2-2) The real-time precise orbit difference and the real-time precise clock difference obtained in step (2-1) are used to calculate the actual value of the spatial distance error of the last time the broadcast ephemeris was broadcast:

[0015]

[0016] In the formula, Δρ C Indicates the actual value of the spatial distance error, is the line of sight vector from the satellite to the receiver, δx C Indicates the real-time precise orbit difference, δt C represents the real-time precise clock difference, c is the speed of light, r is the receiver, and the superscript C represents the Beidou satellite;

[0017] (2-3) According to the actual value of the real-time spatial distance error, the Allan variance of the spatial distance error is estimated according to the following formula:

[0018]

[0019] In the formula, is the Allan variance at the sampling interval τ; q0 represents phase-modulated white noise, q1 represents frequency-modulated white noise, q2 represents frequency-modulated random walk noise, and q3 represents random running noise. q0, q1, q2, and q3 are estimated by using the least squares method to estimate the actual value of the real-time spatial distance error.

[0020] Furthermore, step (3) specifically includes:

[0021] According to the Allan variance of the spatial distance error, the random walk is used to estimate the parameters of the spatial distance error to obtain the estimated value of the spatial distance error of this timing. Among them, the prior noise variance used by the random walk is:

[0022] w=(δ Allan (τ)·τ·c) 2

[0023] Where w is the prior noise variance, δ Allan (τ) is the Allan variance of the spatial distance error, c is the speed of light, and τ is the sampling time.

[0024] Furthermore, the broadcast ephemeris single Beidou PPP timing model based on spatial distance error described in step (4) is specifically:

[0025]

[0026] In the formula, IF is the ionosphere-free combined observation value, r represents the receiver, and C in the above table represents the Beidou satellite. is the pseudorange observation value, is the carrier observation value; is the estimated value of the spatial distance error of this timing, Indicates the spatial distance between the Beidou satellite and the receiver, dt r is the receiver clock error, dt C is the satellite clock error, is the tropospheric delay, is the pseudorange noise, is the floating point disambiguation degree, is the carrier noise.

[0027] Furthermore, step (6) specifically includes:

[0028] (6-1) The clock steering parameters are estimated using the estimated receiver clock error. The specific calculation formula is as follows:

[0029]

[0030] Where, dt r Indicates the receiver clock error, T0 is the initial frequency deviation of the crystal oscillator, A0 is the initial time deviation of the clock, is the random noise error of the crystal oscillator, A represents the frequency drift or frequency aging coefficient of the crystal oscillator, and the estimated clock driving parameters include A0 and A;

[0031] (6-2) synthesizing the tamed clock signal using direct digital frequency synthesis technology according to the clock driving parameters;

[0032] (6-3) The disciplined clock signal is sent to the Beidou satellite receiver, so that the Beidou satellite receiver outputs the corrected time information and completes precise timing.

[0033] A computer device comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the above method.

[0034] A single Beidou global precision timing system based on broadcast ephemeris, comprising:

[0035] Beidou satellite receiver, used to receive observation data and broadcast ephemeris data sent by Beidou satellites, and when receiving disciplined clock signals, output corrected time information to complete precise timing;

[0036] The parsing module is used to obtain the broadcast ephemeris data and satellite observation data sent by Beidou satellites, and parse the broadcast ephemeris data to obtain real-time satellite orbits and real-time satellite clock errors;

[0037] The spatial distance error estimation module is used to calculate the actual value of the spatial distance error of the last broadcast ephemeris timing according to the difference between the real-time satellite orbit and the real-time satellite clock difference and the Beidou satellite precision product released by the international GNSS service, and estimate the Allan variance of the spatial distance error according to the actual value of the spatial distance error. Then, the spatial distance error is estimated according to the Allan variance of the spatial distance error to obtain the estimated value of the spatial distance error of this timing;

[0038] The receiver clock error correction module is used to establish a broadcast ephemeris single Beidou PPP timing model based on the spatial distance error, substitute the satellite observation data and the estimated value of the spatial distance error into the broadcast ephemeris single Beidou PPP timing model, and correct the receiver clock error according to the broadcast ephemeris single Beidou PPP timing model;

[0039] The clock training module is used to train the clock according to the corrected receiver clock error and send the trained clock signal to the Beidou satellite receiver.

[0040] Compared with the prior art, the present invention has the following beneficial effects: the present invention not only improves the timing accuracy, but also expands the scope of application, especially in an environment without network coverage, it can also provide high-precision timing services. This technology can provide users in various environments with high-precision, stable and reliable time information. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a flow chart of an embodiment of a single Beidou global precise timing method based on broadcast ephemeris provided by the present invention;

[0042] Figure 2It is a structural diagram of an embodiment of a single Beidou global precision timing system based on broadcast ephemeris provided by the present invention;

[0043] Figure 3 It is a comparison chart of experimental results between the present invention and the traditional technology. DETAILED DESCRIPTION

[0044] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0045] Embodiment 1

[0046] This embodiment provides a single Beidou global precise timing method based on broadcast ephemeris, such as Figure 1 As shown, the following steps are included:

[0047] (1) Obtain the broadcast ephemeris data and satellite observation data sent by Beidou satellites, and parse the broadcast ephemeris data to obtain real-time satellite orbits and real-time satellite clock errors.

[0048] In this step, satellite observation data includes values ​​observed by Beidou satellites, such as pseudorange observation values ​​and carrier observation values, and broadcast ephemeris data is a type of data containing satellite orbit information and satellite clock correction parameters, which is transmitted and broadcasted from satellites via radio signals for use by receivers. Usually, the corresponding ICD (Interface Control Document) files, also known as "interface control documents", are used to parse satellite data.

[0049] (2) Based on the differences between the real-time satellite orbit and real-time satellite clock error and the Beidou satellite precision products released by the International GNSS Service (IGS), the actual value of the spatial distance error of the last broadcast ephemeris time is calculated, and based on the actual value of the spatial distance error, the Allan variance of the spatial distance error is estimated.

[0050] This step specifically includes:

[0051] (2-1) Subtract the real-time satellite orbit from the precise satellite orbit of the Beidou satellite precision product, and use the difference as the real-time precise orbit difference; subtract the real-time satellite clock error from the precise satellite clock error of the Beidou satellite precision product, and use the difference as the real-time precise clock error difference;

[0052] (2-2) The real-time precise orbit difference and the real-time precise clock difference obtained in step (2-1) are used to calculate the actual value of the spatial distance error of the last time the broadcast ephemeris was broadcast:

[0053]

[0054] In the formula, Δρ C Indicates the actual value of the spatial distance error, is the line of sight vector from the satellite to the receiver, δx C Indicates the real-time precise orbit difference, δt C represents the real-time precise clock difference, c is the speed of light, r is the receiver, and the superscript C represents the Beidou satellite;

[0055] (2-3) According to the actual value of the real-time spatial distance error, the Allan variance of the spatial distance error is estimated according to the following formula:

[0056]

[0057] In the formula, is the Allan variance at the sampling interval τ; q0 represents phase-modulated white noise, q1 represents frequency-modulated white noise, q2 represents frequency-modulated random walk noise, and q3 represents random running noise. q0, q1, q2, and q3 are estimated by using the least squares method to estimate the actual value of the real-time spatial distance error.

[0058] (3) Estimate the spatial distance error based on the Allan variance of the spatial distance error to obtain the estimated value of the spatial distance error for this timing.

[0059] Specifically, the random walk is used to estimate the parameters of the spatial distance error to obtain the estimated value of the spatial distance error of this timing. The prior noise variance used by the random walk is:

[0060] w=(δ Allan (τ)·τ·c) 2 (3)

[0061] Where w is the prior noise variance, δ Allan (τ) is the Allan variance of the spatial distance error, c is the speed of light, and τ is the sampling time.

[0062] (4) Establish a single Beidou PPP timing model based on broadcast ephemeris and spatial distance error.

[0063] Among them, the broadcast ephemeris single Beidou PPP timing model is specifically as follows:

[0064]

[0065] Where, IF is the ionosphere-free combined observation value. In this embodiment, the single Beidou uses the B1I / B3I combination to eliminate the ionosphere, r represents the receiver, and C in the above table represents the Beidou satellite. is the pseudorange observation value, is the carrier observation value; is the estimated value of the spatial distance error of this timing, Indicates the spatial distance between the Beidou satellite and the receiver, dt ris the receiver clock error including pseudorange hardware delay, dt C is the satellite clock error, is the tropospheric delay, is the pseudorange noise, is the floating point disambiguation degree, is the carrier noise.

[0066] (5) Substitute the satellite observation data and the estimated value of the spatial distance error into the broadcast ephemeris single Beidou PPP timing model and solve the model to obtain the corrected receiver clock error.

[0067] When correcting the receiver clock error, an error equation is constructed based on the single Beidou PPP timing model after substitution of the broadcast ephemeris, that is, the error equation of formula (4); then the Kalman filtering method is used to estimate the parameters of the error equation to obtain the corrected receiver clock error.

[0068] The parameter estimation steps of the error equation are as follows: first, according to the real-time satellite orbit and real-time satellite clock error parsed in step (1), the errors of satellite orbit and satellite clock error in the broadcast ephemeris single Beidou PPP timing model are eliminated; secondly, the satellite antenna phase center error, relativistic effect, atmospheric error, receiver antenna phase center error, and tidal use model are directly corrected; finally, the parameters of the tropospheric wet component, receiver clock error, ISB, receiver coordinates, and floating point resolution are estimated, among which the receiver coordinates are estimated statically, the receiver clock error is estimated using white noise, the ambiguity is estimated using a constant, and the tropospheric wet component is estimated using a random walk.

[0069] (6) Perform clock training based on the corrected receiver clock error, and send the trained clock signal to the Beidou satellite receiver, so that the Beidou satellite receiver outputs the corrected time information and completes precise timing.

[0070] This step specifically includes:

[0071] (6-1) The clock steering parameters are estimated using the estimated receiver clock error. The specific calculation formula is as follows:

[0072]

[0073] Where, dt r Indicates the receiver clock error, T0 is the initial frequency deviation of the crystal oscillator, A0 is the initial time deviation of the clock, is the random noise error of the crystal oscillator, A represents the frequency drift or frequency aging coefficient of the crystal oscillator, and the estimated clock driving parameters include A0 and A;

[0074] In order to improve the accuracy and reliability of data processing, the receiver clock error is preprocessed in real time by using the sliding window median detection method, and then the clock steering parameter is estimated;

[0075] (6-2) synthesizing the tamed clock signal using direct digital frequency synthesis technology according to the clock driving parameters;

[0076] (6-3) The disciplined 10MHz clock signal is sent to the Beidou satellite receiver, so that the Beidou satellite receiver outputs the corrected time information, specifically the 1PPS (pulse per second) signal and the UTC (coordinated universal time) time information, to complete the precise timing.

[0077] Embodiment 2

[0078] This embodiment provides a computer device, which provides services for implementing the method of the above-mentioned embodiment 1. The device may include: a memory storing a computer executable program; a processor coupled to the memory; the processor calls the computer executable program stored in the memory to execute the steps in the method described in the embodiment 1.

[0079] The memory may include computer system readable media in the form of volatile memory, such as random access memory (RAM) and / or cache memory. The device may further include other removable / non-removable, volatile / non-volatile computer system storage media. By way of example only, the memory may be used to read and write non-removable, non-volatile magnetic media (commonly referred to as "hard drives"). A program / utility having a set (at least one) of program modules may be stored in, for example, the memory, such program modules including but not limited to an operating system, one or more application programs, other program modules, and program data, each of which or some combination may include an implementation of a network environment. The computer executable program of the program module typically performs the functions and / or methods in the embodiments described in the present invention.

[0080] The processor executes various functional applications and data processing by running the program stored in the memory, such as implementing the method provided in the first embodiment of the present invention.

[0081] The code of the computer executable program can be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, C++, and conventional procedural programming languages ​​such as "C" language or similar programming languages.

[0082] Embodiment 3

[0083] This embodiment provides a single Beidou global precise timing system based on broadcast ephemeris. The system can be implemented in software and / or hardware, such as Figure 2 As shown, including:

[0084] Beidou satellite receiver, used to receive observation data and broadcast ephemeris data sent by Beidou satellites, and when receiving disciplined clock signals, output corrected time information to complete precise timing;

[0085] The parsing module is used to obtain the broadcast ephemeris data and satellite observation data sent by Beidou satellites, and parse the broadcast ephemeris data to obtain real-time satellite orbits and real-time satellite clock errors;

[0086] The spatial distance error estimation module is used to calculate the actual value of the spatial distance error of the last broadcast ephemeris timing according to the difference between the real-time satellite orbit and the real-time satellite clock difference and the Beidou satellite precision product released by the international GNSS service, and estimate the Allan variance of the spatial distance error according to the actual value of the spatial distance error. Then, the spatial distance error is estimated according to the Allan variance of the spatial distance error to obtain the estimated value of the spatial distance error of this timing;

[0087] The receiver clock error correction module is used to establish a broadcast ephemeris single Beidou PPP timing model based on the spatial distance error, substitute the satellite observation data and the estimated value of the spatial distance error into the broadcast ephemeris single Beidou PPP timing model, and correct the receiver clock error according to the broadcast ephemeris single Beidou PPP timing model;

[0088] The clock training module is used to train the clock according to the corrected receiver clock error and send the trained clock signal to the Beidou satellite receiver.

[0089] Among them, the spatial distance error estimation module specifically includes:

[0090] A difference calculation unit is used to make a difference between the real-time satellite orbit and the precise satellite orbit of the Beidou satellite precision product, and the difference is used as the real-time precise orbit difference; and to make a difference between the real-time satellite clock error and the precise satellite clock error of the Beidou satellite precision product, and the difference is used as the real-time precise clock error difference;

[0091] The space distance error actual value calculation unit is used to calculate the space distance error actual value of the last time the broadcast ephemeris is synchronized with the real-time precise orbit difference and the real-time precise clock difference:

[0092]

[0093] In the formula, Δρ C Indicates the actual value of the spatial distance error, is the line of sight vector from the satellite to the receiver, δx CIndicates the real-time precise orbit difference, δt C represents the real-time precise clock difference, c is the speed of light, r is the receiver, and the superscript C represents the Beidou satellite;

[0094] The spatial distance error Allan variance calculation unit is used to estimate the Allan variance of the spatial distance error according to the following formula based on the actual value of the real-time spatial distance error:

[0095]

[0096] In the formula, is the Allan variance at the sampling interval τ; q0 represents phase-modulated white noise, q1 represents frequency-modulated white noise, q2 represents frequency-modulated random walk noise, and q3 represents random running noise. q0, q1, q2, and q3 are estimated by using the least squares method to estimate the actual value of the real-time spatial distance error.

[0097] The spatial distance error estimation unit is used to estimate the spatial distance error according to the Allan variance of the spatial distance error to obtain the estimated value of the spatial distance error of this timing. Specifically, the spatial distance error is estimated by using random walk to obtain the estimated value of the spatial distance error of this timing; wherein the priori noise variance used by the random walk is:

[0098] w=(δ Allan (τ)·τ·c) 2 (3)

[0099] Where w is the prior noise variance, δ Allan (τ) is the Allan variance of the spatial distance error, c is the speed of light, and τ is the sampling time.

[0100] The receiver clock error correction module specifically includes:

[0101] The model acquisition unit is used to obtain the broadcast ephemeris single Beidou PPP timing model, specifically:

[0102]

[0103] Where, IF is the ionosphere-free combined observation value. In this embodiment, the single Beidou uses the B1I / B3I combination to eliminate the ionosphere, r represents the receiver, and C in the above table represents the Beidou satellite. is the pseudorange observation value, is the carrier observation value; is the estimated value of the spatial distance error of this timing, Indicates the spatial distance between the Beidou satellite and the receiver, dt r is the receiver clock error including pseudorange hardware delay, dt C is the satellite clock error, is the tropospheric delay, is the pseudorange noise, is the floating point disambiguation degree, is the carrier noise;

[0104] The correction unit is used to substitute the satellite observation data and the estimated value of the space distance error into the broadcast ephemeris single Beidou PPP timing model, and solve the model to obtain the corrected receiver clock error.

[0105] The clock taming module specifically includes:

[0106] The clock control parameter estimation unit is used to estimate the clock control parameter using the estimated receiver clock difference. The specific calculation formula is as follows:

[0107]

[0108] Where, dt r Indicates the receiver clock error, T0 is the initial frequency deviation of the crystal oscillator, A0 is the initial time deviation of the clock, is the random noise error of the crystal oscillator, A represents the frequency drift or frequency aging coefficient of the crystal oscillator, and the estimated clock driving parameters include A0 and A;

[0109] In order to improve the accuracy and reliability of data processing, the receiver clock error is preprocessed in real time by using the sliding window median detection method, and then the clock steering parameter is estimated;

[0110] A clock signal synthesis unit, used for synthesizing a tamed clock signal using a direct digital frequency synthesis technique according to clock driving parameters;

[0111] The signal sending unit is used to send the disciplined 10MHz clock signal to the Beidou satellite receiver, so that the Beidou satellite receiver outputs the corrected time information, specifically the 1PPS (pulse per second) signal and UTC (coordinated universal time) time information, to complete precise timing.

[0112] The system provided in the embodiment of the present invention can be used to execute the method provided in the first embodiment of the present invention, and has the corresponding functions and beneficial effects of the execution method.

[0113] It is worth noting that in the embodiment of the above system, the various units and modules included are only divided according to functional logic, but are not limited to the above division, as long as the corresponding functions can be achieved; in addition, the specific names of the functional units are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of the present invention.

[0114] The embodiments described above are only illustrative, wherein the modules described as separate components may or may not be physically separated, and the components displayed as modules may or may not be physical modules, i.e., they may be located in one place, or they may be distributed on multiple network modules. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, or of course, it can be implemented only by hardware, as long as the function or effect can be achieved.

[0115] The present invention was tested, and the experimental results are as follows Figure 3 As shown, by comparing the timing results calculated by the present invention with the results obtained by the traditional satellite timing method, it can be obviously observed that compared with the traditional satellite timing based on broadcast ephemeris, the timing accuracy of the present invention will be improved by 2 orders of magnitude. Compared with the traditional PPP timing based on broadcast ephemeris, the present invention can effectively reduce the fluctuation of the timing results and improve the long-term stability of the timing.

[0116] It should be understood that the above embodiments and descriptions only describe the principles, main features and advantages of the present invention. Without departing from the spirit and scope of the present invention, the present invention may be subject to various changes and improvements, and these changes and improvements all fall within the scope of protection of the present invention.

Claims

1. A single Beidou global precise timing method based on broadcast ephemeris, characterized in that: The steps include: (1) Obtain the broadcast ephemeris data and satellite observation data sent by Beidou satellites, and parse the broadcast ephemeris data to obtain real-time satellite orbits and real-time satellite clock errors; (2) Based on the differences between the real-time satellite orbit and real-time satellite clock error and the Beidou satellite precision products released by the international GNSS service, the actual value of the spatial distance error of the last broadcast ephemeris time is calculated, and based on the actual value of the spatial distance error, the Allan variance of the spatial distance error is estimated; (3) Estimate the spatial distance error based on the Allan variance of the spatial distance error to obtain the estimated value of the spatial distance error for this timing; (4) Establish a single Beidou PPP timing model based on broadcast ephemeris and spatial distance error; (5) Substitute the satellite observation data and the estimated value of the spatial distance error into the broadcast ephemeris single Beidou PPP timing model and solve the model to obtain the corrected receiver clock error; (6) Perform clock training based on the corrected receiver clock error, and send the trained clock signal to the Beidou satellite receiver, so that the Beidou satellite receiver outputs the corrected time information and completes precise timing.

2. The single Beidou global precise timing method based on broadcast ephemeris according to claim 1, characterized in that: Step (2) specifically includes: (2-1) Subtract the real-time satellite orbit from the precise satellite orbit of the Beidou satellite precision product, and use the difference as the real-time precise orbit difference; subtract the real-time satellite clock error from the precise satellite clock error of the Beidou satellite precision product, and use the difference as the real-time precise clock error difference; (2-2) The real-time precise orbit difference and the real-time precise clock difference obtained in step (2-1) are used to calculate the actual value of the spatial distance error of the last time the broadcast ephemeris was broadcast: In the formula, Δρ C Indicates the actual value of the spatial distance error, is the line of sight vector from the satellite to the receiver, δx C Indicates the real-time precise orbit difference, δt C represents the real-time precise clock difference, c is the speed of light, r is the receiver, and the superscript C represents the Beidou satellite; (2-3) According to the actual value of the real-time spatial distance error, the Allan variance of the spatial distance error is estimated according to the following formula: In the formula, is the Allan variance at the sampling interval τ; q0 represents phase-modulated white noise, q1 represents frequency-modulated white noise, q2 represents frequency-modulated random walk noise, and q3 represents random running noise. q0, q1, q2, and q3 are estimated by using the least squares method to estimate the actual value of the real-time spatial distance error.

3. The single Beidou global precise timing method based on broadcast ephemeris according to claim 1, characterized in that: Step (3) specifically includes: According to the Allan variance of the spatial distance error, the random walk is used to estimate the parameters of the spatial distance error to obtain the estimated value of the spatial distance error of this timing. Among them, the prior noise variance used by the random walk is: w=(δ Allan (t)·t·c) 2 Where w is the prior noise variance, δ Allan (τ) is the Allan variance of the spatial distance error, c is the speed of light, and τ is the sampling time.

4. The single Beidou global precise timing method based on broadcast ephemeris according to claim 1, characterized in that: The broadcast ephemeris single Beidou PPP timing model based on spatial distance error described in step (4) is specifically: In the formula, IF is the ionosphere-free combined observation value, r represents the receiver, and C in the above table represents the Beidou satellite. is the pseudorange observation value, is the carrier observation value; is the estimated value of the spatial distance error of this timing, Indicates the spatial distance between the Beidou satellite and the receiver, dt r is the receiver clock error, dt C is the satellite clock error, is the tropospheric delay, is the pseudorange noise, is the floating point disambiguation degree, is the carrier noise.

5. The single Beidou global precise timing method based on broadcast ephemeris according to claim 1, characterized in that: Step (5) comprises: (5-1) Substitute the satellite observation data and the estimated value of the spatial distance error into the broadcast ephemeris single Beidou PPP timing model, and construct the error equation based on the substituted broadcast ephemeris single Beidou PPP timing model; (5-2) The Kalman filtering method is used to estimate the parameters of the error equation to obtain the corrected receiver clock error.

6. The single Beidou global precise timing method based on broadcast ephemeris according to claim 5, characterized in that: Step (5-2) includes: (5-2-1) Eliminate the satellite orbit and satellite clock error in the broadcast ephemeris single Beidou PPP timing model according to the real-time satellite orbit and real-time satellite clock error parsed in step (1); (5-2-2) Direct correction of satellite antenna phase center error, relativistic effect, atmospheric error, receiver antenna phase center error, and tidal use model; (5-2-3) Parameter estimation is performed on the tropospheric wet component, receiver clock error, ISB, receiver coordinates, and floating-point deambiguity. The receiver coordinates are estimated using static parameters, the receiver clock error is estimated using white noise, the ambiguity is estimated using a constant, and the tropospheric wet component is estimated using a random walk.

7. The single Beidou global precise timing method based on broadcast ephemeris according to claim 1, characterized in that: Step (6) specifically includes: (6-1) The clock steering parameters are estimated using the estimated receiver clock error. The specific calculation formula is as follows: Where, dt r Indicates the receiver clock error, T0 is the initial frequency deviation of the crystal oscillator, A0 is the initial time deviation of the clock, is the random noise error of the crystal oscillator, A represents the frequency drift or frequency aging coefficient of the crystal oscillator, and the estimated clock driving parameters include A0 and A; (6-2) synthesizing the tamed clock signal using direct digital frequency synthesis technology according to the clock driving parameters; (6-3) The disciplined clock signal is sent to the Beidou satellite receiver, so that the Beidou satellite receiver outputs the corrected time information and completes precise timing.

8. The single Beidou global precise timing method based on broadcast ephemeris according to claim 7, characterized in that: Before estimating the clock steering parameters, the receiver clock error is preprocessed using the sliding window median detection method.

9. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: The processor executes the computer program to implement the method according to any one of claims 1 to 8.

10. A single Beidou global precision timing system based on broadcast ephemeris, characterized in that: include: Beidou satellite receiver, used to receive observation data and broadcast ephemeris data sent by Beidou satellites, and when receiving disciplined clock signals, output corrected time information to complete precise timing; The parsing module is used to obtain the broadcast ephemeris data and satellite observation data sent by Beidou satellites, and parse the broadcast ephemeris data to obtain real-time satellite orbits and real-time satellite clock errors; The spatial distance error estimation module is used to calculate the actual value of the spatial distance error of the last broadcast ephemeris timing according to the difference between the real-time satellite orbit and the real-time satellite clock difference and the Beidou satellite precision product released by the international GNSS service, and estimate the Allan variance of the spatial distance error according to the actual value of the spatial distance error. Then, the spatial distance error is estimated according to the Allan variance of the spatial distance error to obtain the estimated value of the spatial distance error of this timing; The receiver clock error correction module is used to establish a broadcast ephemeris single Beidou PPP timing model based on the spatial distance error, substitute the satellite observation data and the estimated value of the spatial distance error into the broadcast ephemeris single Beidou PPP timing model, and correct the receiver clock error according to the broadcast ephemeris single Beidou PPP timing model; The clock training module is used to train the clock according to the corrected receiver clock error and send the trained clock signal to the Beidou satellite receiver.

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