Analysis method for influence of satellite-ground synchronization accuracy on user timing deviation
By superimposing noise simulation and modeling in the satellite-ground synchronization accuracy analysis, the clock difference parameter estimate value is calculated, and the impact analysis problem of the satellite-ground synchronization accuracy on user timing deviation is solved, and the timing accuracy and reliability of the navigation system are improved.
Patent Information
- Application Number
- CN202310441476.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-04-23
- Publication Date
- 2025-07-08
- Estimated Expiration
- 2043-04-23
AI Technical Summary
The prior art cannot effectively analyze the impact of star-ground synchronization accuracy on user timing deviation, resulting in insufficient timing accuracy of navigation systems.
By superimposing noise on the clock difference data for simulation, a star-ground clock difference model is established, the clock difference parameter estimate value is calculated, and the clock difference prediction error is analyzed. The timing results are calculated based on the pseudorange and carrier phase observations, and the clock difference prediction error is included, and the timing error and uncertainty are calculated.
It realizes accurate analysis of user timing deviations by star-ground synchronization accuracy, improves the timing accuracy and reliability of the navigation system, is low in cost and wide in scope of application.
Smart Images
Figure CN116506301B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of satellite communication. More specifically, it relates to a method for analyzing the influence of satellite-ground synchronization accuracy on user timing deviation. Background Art
[0002] Global Navigation Satellite System (GNSS) mainly includes the GPS system of the United States, the GLONASS system of Russia, the Galileo system of Europe, and the Beidou Satellite Navigation System (BDS) of China. They are designed to provide all-weather, high-precision positioning, navigation, and timing (PNT) services for global users. The satellite navigation system consists of three parts: the space segment, the ground segment, and the user segment. The atomic clock is the heart of major satellite navigation and positioning systems, which provides a highly stable time-frequency reference signal for the satellite navigation system and plays a decisive role in the navigation and positioning, speed measurement, and timing accuracy of the navigation system.
[0003] The core of the navigation system is time measurement. In the satellite navigation system, a time error of 1 ns is equivalent to a distance error of 0.3 m. The atomic clock provides a reference signal for the navigation system. The main factors affecting time measurement are: the performance of the atomic clock itself and the satellite-ground time synchronization accuracy. High-precision atomic clocks are configured in both the space segment and the ground segment of the satellite navigation system. However, as the service duration of on-board atomic clocks continues to increase, their performance indicators will inevitably change, and the accuracy and stability indicators of the atomic clocks will decline. Due to the objective reason that on-board atomic clocks cannot be calibrated on-site, the method of satellite-ground time synchronization is adopted to ensure that the atomic clocks of each satellite are synchronized with the atomic clock of the main control station in the ground segment, thereby maintaining the time reference of the navigation system.
[0004] The higher the satellite-ground synchronization accuracy and the smaller the error, the higher the timing accuracy. The satellite-ground synchronization accuracy plays a crucial role in the entire navigation system. The present invention provides a method for analyzing the influence of satellite-ground synchronization accuracy on user timing deviation, which can specifically analyze the influence of synchronization accuracy on user timing results. Summary of the Invention
[0005] An object of the present invention is to provide a method for analyzing the influence of satellite-ground synchronization accuracy on user timing deviation to solve at least one of the problems existing in the prior art.
[0006] To achieve the above object, the present invention adopts the following technical solutions:
[0007] In the first aspect of the present invention, a method for analyzing the influence of satellite-ground synchronization accuracy on user timing deviation is provided, including:
[0008] Superimpose noise on the clock difference data and simulate the satellite-ground synchronization data to obtain satellite-ground clock difference simulation data;
[0009] Model the satellite-ground clock difference simulation data to obtain a clock difference model;
[0010] Calculate the estimated values of the clock difference parameters of the satellite-ground clock difference simulation data;
[0011] Calculate the clock difference prediction error based on the estimated values of the clock difference parameters and the clock difference model.
[0012] Preferably, the method further includes
[0013] Calculate the timing error caused by the satellite-ground synchronization accuracy based on the clock difference prediction error, and analyze the influence of the satellite-ground synchronization accuracy on the user's timing deviation.
[0014] Preferably, the method further includes
[0015] Calculate the uncertainty of the clock difference parameters according to the expression of the estimated values of the clock difference parameters, and calculate the clock difference estimation uncertainty and the confidence probability interval according to the uncertainty propagation law.
[0016] Preferably, the method further includes
[0017] The clock difference data is ideal clock difference data.
[0018] Preferably, the superimposing noise to simulate the satellite-ground clock difference data includes
[0019] Superimpose Gaussian white noise on the ideal clock difference data to simulate the satellite-ground synchronization data, and obtain the satellite-ground clock difference simulation data.
[0020] Preferably, the modeling of the satellite-ground clock difference simulation data includes
[0021] Use a quadratic polynomial to model the satellite-ground clock difference data.
[0022] Preferably, the calculating the estimated values of the clock difference parameters of the satellite-ground clock difference simulation data includes
[0023] Perform least squares fitting on the satellite-ground clock difference data simulation data, and calculate the estimated values of the clock difference parameters.
[0024] Preferably, the calculating the timing error caused by the satellite-ground synchronization accuracy according to the clock difference prediction error includes
[0025] When using pseudorange observations or carrier phase observations to solve the timing result, the same part of the clock difference prediction errors of all satellites participating in the calculation is included in the timing result.
[0026] In a second aspect of the present invention, there is provided a computer device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, the method provided in the first aspect of the present invention is implemented.
[0027] In a third aspect of the present invention, there is provided a computer-readable storage medium, on which a computer program is stored. When the program is executed by a processor, the method provided in the first aspect of the present invention is implemented.
[0028] The beneficial effects of the present invention are as follows:
[0029] The present invention is used to analyze the influence of satellite-ground synchronization accuracy on user timing deviation. The method is simple and effective, with low cost and a wider application range, and can specifically analyze the influence of satellite-ground synchronization accuracy on user timing results. BRIEF DESCRIPTION OF THE DRAWINGS
[0030] The following further describes in detail the specific embodiments of the present invention with reference to the accompanying drawings.
[0031] Figure 1 The flowchart of the method for analyzing the influence of satellite-ground synchronization accuracy according to the present invention is shown. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0032] To more clearly illustrate the present invention, the present invention will be further described below with reference to preferred embodiments and the accompanying drawings. Similar components in the drawings are denoted by the same reference numerals. Those skilled in the art should understand that the content specifically described below is illustrative rather than restrictive, and should not be used to limit the protection scope of the present invention.
[0033] The purpose of the present invention is to establish a method for analyzing the influence of satellite-ground synchronization accuracy on user timing deviation based on ideal clock offset data. This method can be used to analyze the influence of satellite-ground synchronization accuracy on user timing deviation, and further can also analyze the uncertainty of clock offset estimation.
[0034] Figure 1 The data processing flow of the method for analyzing the influence of satellite-ground synchronization accuracy according to the present invention is shown.
[0035] Based on the ideal clock offset data, satellite-ground synchronization data is simulated by superimposing noise to obtain satellite-ground clock offset simulation data.
[0036] The satellite-ground clock offset simulation data is modeled and calculated to obtain the estimated value of the clock offset parameter of the satellite-ground clock offset simulation data.
[0037] After obtaining the estimated value of the clock offset parameter, the clock offset data at a future moment is predicted according to the adopted model polynomial, and is epoch-aligned with the simulation clock offset data to obtain the corresponding clock offset prediction error.
[0038] Further calculate the timing error caused by the satellite-ground synchronization accuracy according to the prediction error of the on-board clock of the visible satellite, and analyze the uncertainty of the clock error estimation.
[0039] Simulate the satellite-ground synchronization data
[0040] Specifically, when analyzing the influence of the synchronization accuracy on the user's timing deviation, it is assumed that the on-board atomic clock is in an ideal state with very good stability, that is, the satellite-ground clock difference is always a fixed value.
[0041] At this time, the noise introduced in the satellite-ground synchronization process can be regarded as Gaussian white noise.
[0042] Simulate the satellite-ground clock difference data (satellite-ground synchronization data) by superimposing Gaussian white noise on the ideal and stable clock difference, and obtain the satellite-ground clock difference simulation data.
[0043] Model the satellite-ground clock difference simulation data
[0044] Specifically, after simulating and obtaining the satellite-ground clock difference simulation data, model the satellite-ground clock difference simulation data according to the on-board clock difference model.
[0045] In actual situations, the deviation of the on-board atomic clock relative to the system time at time t can be represented by a quadratic polynomial, which involves four parameters; it includes three clock difference parameters and the reference time of the clock difference parameters of this group.
[0046] The present invention uses a quadratic polynomial to model the satellite-ground clock difference simulation data.
[0047] Calculate the estimated values of the clock difference parameters of the satellite-ground clock difference simulation data
[0048] Specifically, through the least square fitting of the satellite-ground clock difference simulation data, the estimators of the clock difference parameters are calculated. The least square estimation method finds the best function matching of the parameters by minimizing the sum of the squares of the residuals. Using the least square estimation method, the three clock difference parameters can be simply obtained, and the sum of the squares of the errors between the clock difference values corresponding to the estimated values of the clock difference parameters and the actual clock difference data is minimized.
[0049] Assume that a given set of observed values is (t i , D i )(i = 1, 2,..., n), establish a clock difference model using a quadratic polynomial, and for the clock difference data D1, D2, D3,..., D n Adopt second-order least square fitting, and the minimum value point of the fitting function is the clock difference parameter to be solved. Take the partial derivatives of the fitting function with respect to the three clock difference parameters respectively, and then solve the system of partial derivative equations to obtain the estimated values of the clock difference parameters.
[0050] Specifically, substitute the calculated estimated values of the clock difference parameters into the clock difference model to predict the on-board clock difference at future times.
[0051] The prediction error of the clock error parameter refers to the difference between each clock error data predicted using the clock error model parameters and the original clock error data, and each clock error data corresponds to a prediction error. The degree of coincidence (clock error prediction error) between the predicted value and the simulated value of the clock error data is used as the basis for subsequent analysis.
[0052] The time series of the superimposed white noise is different in each simulation, which has different effects on the least squares fitting of the clock error simulation data, resulting in different solved clock error parameters, and further affecting the prediction of the clock error data, leading to a large difference in the clock error prediction error obtained in each simulation.
[0053] Based on this, in order to more accurately analyze the relationship between the time synchronization accuracy and the prediction error, a large number of simulations can be carried out, and the average of the prediction error statistical values corresponding to multiple simulations is calculated and used as the evaluation basis for analyzing the relationship between the synchronization accuracy and the prediction error.
[0054] Analysis of the influence of satellite-ground synchronization accuracy on the user's timing deviation includes
[0055] Each satellite corresponds to a clock error prediction error. When the user uses the pseudorange observation value or the carrier phase observation value to solve the timing result, the clock error prediction error will inevitably affect its timing result. The clock error prediction errors caused by the synchronization accuracy of each visible satellite are generally different. When solving the observation equation, the same part of the clock error prediction errors of all the satellites participating in the calculation will be included in the user's timing result.
[0056] Analysis of the uncertainty of clock error estimation includes
[0057] According to the obtained expression of the clock error parameter estimation value, the corresponding residual and the standard deviation estimation value of a single measurement are calculated. Further calculate the uncertainty of the clock error parameter, and the clock error estimation uncertainty and the corresponding confidence probability interval can be calculated according to the law of propagation of uncertainty.
[0058] A specific embodiment
[0059] Let the ideal clock error sequence be (t i , D i '), D i ' is a set of data per second, and the data duration is 12 hours. According to the analysis result of introducing noise in the actual time synchronization process, the noise introduced in the synchronization process is random noise. Assume that a Gaussian white noise with a mean of 0 and a standard deviation of 0.3 ns is superimposed, and the clock error sequence after adding the noise is (t i , D i ).
[0060] Use a quadratic polynomial to model the clock error sequence D i For the clock error sequences D1, D2, D3,..., D of 2 hoursn Perform second-order least squares fitting. The minimum point of the fitting function is the clock error parameter to be solved. Take the partial derivatives of the fitting function with respect to the three clock error parameters respectively, and then solve the equations to obtain the estimated values of the clock error parameters.
[0061] Using the estimated values of the clock error parameters obtained from the solution, substitute them into the quadratic polynomial model to predict the clock error sequence at future times. Assume predicting the clock error sequence for the next 10 hours, denoted as Y n+i , and the corresponding simulated clock error sequence is D n+i , when the time scales of the two are aligned and subtracted, it is the clock error prediction error at the corresponding time, denoted as δ n+i .
[0062] When the user uses the pseudorange observation value or the carrier phase observation value to solve the user's timing result, assume the visible satellite S k 's clock error prediction error caused by the synchronization accuracy is When solving the equation, the same part of the clock error prediction errors of all satellites participating in the calculation (that is, the minimum value in) is included in the timing result.
[0063] Substitute the expression of the estimated value of the clock error parameter into the residual equation to obtain the residual ν i , and further calculate the estimated value s of the standard deviation of a single measurement. From the expressions of the estimated values of the clock error parameters a, b, c and the standard deviation s of a single measurement, the estimated uncertainties u(a), u(b), u(c) of the clock error parameters can be obtained. The three parameters a, b, c are independent of each other, and the clock error estimated uncertainty can be expressed as:
[0064]
[0065] In the formula:
[0066] u(a), u(b), u(c), u(x) are the uncertainties introduced by a, b, c and x respectively, and c1, c2, c3, c4 are the sensitivity coefficients of a, b, c and x respectively.
[0067]
[0068] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by terms such as "upper" and "lower" is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention. Unless otherwise clearly specified and defined, the terms "installed", "connected" and "coupled" shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.
[0069] It should also be noted that in the description of the present invention, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the phrase "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the said element.
[0070] Obviously, the above embodiments of the present invention are only examples for clearly illustrating the present invention, rather than limitations on the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation manners here. Any obvious changes or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.
Claims
1. A method for analyzing the influence of satellite-ground synchronization accuracy on user timing deviation, characterized in that Including: Superimpose noise on the clock difference data and simulate the satellite-ground synchronization data to obtain satellite-ground clock difference simulation data; Model the satellite-ground clock difference simulation data to obtain a clock difference model; Calculate the estimated value of the clock difference parameter of the satellite-ground clock difference simulation data; Calculate the clock difference prediction error based on the estimated value of the clock difference parameter and the clock difference model; The method further includes Calculate the uncertainty of the clock difference parameter according to the expression of the estimated value of the clock difference parameter, and calculate the clock difference estimation uncertainty and the confidence probability interval according to the uncertainty propagation law.
2. The method according to claim 1, wherein The method further includes Calculate the timing error caused by the satellite-ground synchronization accuracy according to the clock difference prediction error, and analyze the influence of the satellite-ground synchronization accuracy on the user's timing deviation.
3. The method according to claim 1, wherein The method further includes The clock difference data is ideal clock difference data.
4. The method according to claim 1, wherein The superimposed noise simulation of the satellite-ground clock difference data includes Superimpose Gaussian white noise on the ideal clock difference data to simulate the satellite-ground synchronization data to obtain satellite-ground clock difference simulation data.
5. The method according to claim 1, characterized in that, The modeling of the satellite-ground clock difference simulation data includes Use a quadratic polynomial to model the satellite-ground clock difference data.
6. The method according to claim 1, characterized in that, The calculation of the estimated value of the clock difference parameter of the satellite-ground clock difference simulation data includes Perform least squares fitting on the satellite-ground clock difference simulation data to calculate the estimated value of the clock difference parameter.
7. The method according to claim 1, characterized in that, The calculation of the timing error caused by the satellite-ground synchronization accuracy according to the clock difference prediction error includes When using the pseudo-range observation value or the carrier phase observation value to solve the timing result, the same part of the clock difference prediction error of all the satellites participating in the calculation is included in the timing result.
8. A computer device, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, When the processor executes the program, the method described in any one of claims 1-7 is implemented.
9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, the method described in any one of claims 1-7 is implemented.