A method for monitoring the integrity of low-orbit satellite real-time filtering timing and orbit determination

Abstract

The invention discloses a method for monitoring the integrity of real-time filtering timing and orbit determination of a low-orbit satellite, comprising: obtaining a complete upper bound covariance matrix of a low-orbit satellite system observation model of a current epoch; calculating an upper bound form covariance matrix of unknown parameters in the low-orbit satellite system observation model according to the complete upper bound covariance matrix; the unknown parameters include clock error and orbit parameters; obtaining a first upper bound form standard deviation of the clock error and a second upper bound form standard deviation of the orbit parameter according to corresponding elements of the clock error and the orbit parameter in the upper bound form covariance matrix; determining a first influence of deviation transmission of multiple epochs on the clock error and a second influence on the orbit parameter; obtaining a first protection level according to the first upper bound form standard deviation and the first influence, and obtaining a second protection level according to the second upper bound form standard deviation and the second influence; and performing integrity monitoring of real-time filtering timing and orbit determination of the low-orbit satellite based on the first protection level and the second protection level to improve the accuracy of integrity monitoring.

Description

Technical Field

[0001] The invention belongs to the technical field of satellite navigation, and in particular relates to a method for monitoring the integrity of real-time filtering timing and orbit determination of a low-orbit satellite. Background Art

[0002] Thanks to the low altitude, high speed and low cost of low-orbit satellites, low-orbit enhanced GNSS (Global Navigation Satellite System) positioning, navigation and timing have a series of advantages such as strong signal strength, short convergence time and multipath effect whitening, and have received more and more attention in recent years. In order to better utilize low-orbit navigation signals to achieve high-precision real-time positioning and timing on the ground, precise and reliable low-orbit satellite real-time orbit star clock products are an important prerequisite and guarantee, and the integrity of orbit star clock products is also the basis for future low-orbit enhanced GNSS ground positioning, navigation and timing integrity monitoring.

[0003] The existing general integrity monitoring methods usually perform standard single-point positioning for the smooth pseudorange used in civil aviation. Among them, the existing general integrity monitoring methods are divided into the ARAIM (Advanced Receiver Autonomous Integrity Monitoring) algorithm based on broadcast ephemeris solution, and the DFMC (Dual-Frequency Multi-Constellation) SBAS integrity monitoring algorithm for the dual-frequency multi-system SBAS (Satellite-Based Augmentation System) precise star clock ephemeris solution. The working principle of these two integrity monitoring algorithms is to calculate the protection level of the aircraft positioning result and compare it with the alarm threshold according to the integrity risk given in advance. When the protection level exceeds the alarm threshold, the system is judged to be unavailable and an alarm is issued to the system and the user.

[0004] However, the existing general civil aviation integrity monitoring method mainly uses carrier smoothed pseudorange observations and low-precision broadcast GNSS star clock ephemeris for non-filtered single-point positioning. This method is not suitable for real-time orbit determination and timing of precise orbit determination satellites using carrier phase and pseudorange observations and real-time precise GNSS star clock ephemeris in a filtered manner. Summary of the invention

[0005] In order to solve the above problems existing in the prior art, the present invention provides a method for monitoring the integrity of real-time filtering timing and orbit determination of a low-orbit satellite.

[0006] The technical problem to be solved by the present invention is achieved through the following technical solutions:

[0007] In a first aspect, the present invention provides a method for monitoring the integrity of real-time filtering timing and orbit determination of a low-orbit satellite, comprising:

[0008] Get the complete upper bound covariance matrix of the low-orbit satellite system observation model for the current epoch;

[0009] Calculate the upper bound form covariance matrix of unknown parameters in the low-orbit satellite system observation model according to the complete upper bound covariance matrix; the unknown parameters include clock errors and orbital parameters;

[0010] Obtaining a first upper bound form standard deviation of the clock error and a second upper bound form standard deviation of the orbital parameter according to corresponding elements of the clock error and the orbital parameter in the upper bound form covariance matrix;

[0011] Determining a first effect of bias propagation for a plurality of epochs on the clock error and a second effect of the bias propagation on the orbital parameters;

[0012] Obtaining a first protection level according to the first upper bound formal standard deviation and the first impact, and obtaining a second protection level according to the second upper bound formal standard deviation and the second impact;

[0013] Based on the first protection level and the second protection level, integrity monitoring of real-time filtering timing and orbit determination of low-orbit satellites is performed.

[0014] Optionally, obtain the complete upper bound covariance matrix of the low-orbit satellite system observation model for the current epoch, including:

[0015] Determine a first upper bound covariance matrix of an ionospheric-free combination of carrier phase observations and pseudorange observations of a low-orbit satellite system observation model at a current epoch;

[0016] A second upper bound covariance matrix is ​​obtained by using an upper bound covariance matrix of ambiguity parameters with time constraints between the previous epoch and the current epoch; the upper bound covariance matrix of the ambiguity parameters is obtained by using an upper bound covariance matrix of ambiguity parameters solved by the low-orbit satellite system observation model in the previous epoch;

[0017] A complete upper bound covariance matrix of the low-orbit satellite system observation model is obtained according to the first upper bound covariance matrix and the second upper bound covariance matrix.

[0018] Optionally, obtaining a complete upper bound covariance matrix of the low-orbit satellite system observation model according to the first upper bound covariance matrix and the second upper bound covariance matrix includes:

[0019] ;

[0020] in, represents the complete upper bound covariance matrix; represents the first upper bound covariance matrix; represents the second upper bound covariance matrix; It represents the operation of forming a block diagonal matrix with the matrix in brackets; Represents the current epoch.

[0021] Optionally, calculating the upper bound form covariance matrix of unknown parameters in the low-orbit satellite system observation model according to the complete upper bound covariance matrix includes:

[0022] ;

[0023] in, represents the upper bound form covariance matrix; Represents the transpose operation of a matrix; express The design matrix below; , express The design matrix corresponding to the observation equation under ; express The design matrix corresponding to the time constraint equation below.

[0024] Optionally, determining a first effect of bias propagation of a plurality of epochs on the clock error and a second effect of the bias propagation on the orbital parameter comprises:

[0025] Get to The deviation of the deviation in the filter solution is The influence of unknown parameters in ;in, represents the first epoch, Indicates the current epoch the previous epoch of ;

[0026] from The influences corresponding to the clock error and the orbital parameter are extracted respectively, and a first influence of the deviation transfer on the clock error and a second influence of the deviation transfer on the orbital parameter are obtained.

[0027] Optionally, performing integrity monitoring of real-time filtering timing and orbit determination of low-orbit satellites based on the first protection level and the second protection level includes:

[0028] The first protection level is compared with a preset low-orbit satellite clock error alarm threshold, and the second protection level is compared with a preset low-orbit satellite orbit error alarm threshold, and an alarm is issued when the first protection level exceeds the low-orbit satellite clock error alarm threshold and / or the second protection level exceeds the low-orbit satellite orbit error alarm threshold.

[0029] Optionally, obtaining a first protection level according to the first upper bound formal standard deviation and the first impact includes:

[0030] ;

[0031] in, Indicates the first protection level; represents the calculation factor; represents the standard deviation of the first upper bound form; represents the first impact; Represents the current epoch.

[0032] Optionally, obtaining a second protection level according to the second upper bound formal standard deviation and the second impact includes:

[0033] ;

[0034] in, Indicates the second level of protection; represents the calculation factor; represents the second upper bound form standard deviation; represents the second impact; Represents the current epoch.

[0035] In a second aspect, the present invention provides a low-orbit satellite real-time filtering timing and orbit determination integrity monitoring device, comprising:

[0036] An acquisition module, used to obtain the complete upper bound covariance matrix of the low-orbit satellite system observation model of the current epoch;

[0037] An upper bound form covariance matrix calculation module is used to calculate the upper bound form covariance matrix of unknown parameters in the low-orbit satellite system observation model according to the complete upper bound covariance matrix; the unknown parameters include clock errors and orbital parameters;

[0038] A standard deviation determination module, used for obtaining a first upper bound form standard deviation of the clock error and a second upper bound form standard deviation of the orbit parameter according to corresponding elements of the clock error and the orbit parameter in the upper bound form covariance matrix;

[0039] An impact determination module, configured to determine a first impact of bias transfer of a plurality of epochs on the clock error and a second impact of the bias transfer on the orbital parameter;

[0040] a protection level determination module, configured to obtain a first protection level according to the first upper bound formal standard deviation and the first impact, and to obtain a second protection level according to the second upper bound formal standard deviation and the second impact;

[0041] An integrity monitoring module is used to perform integrity monitoring of real-time filtering timing and orbit determination of low-orbit satellites based on the first protection level and the second protection level.

[0042] Optional, get module, specifically used for:

[0043] Determine a first upper bound covariance matrix of an ionosphere-free combination of carrier phase observations and pseudorange observations of a low-orbit satellite system observation model at a current epoch; obtain a second upper bound covariance matrix through an upper bound covariance matrix of ambiguity parameters with time constraints between a previous epoch and a current epoch; obtain a complete upper bound covariance matrix of the low-orbit satellite system observation model according to the first upper bound covariance matrix and the second upper bound covariance matrix; the upper bound covariance matrix of the ambiguity parameters is obtained by an upper bound covariance matrix of the ambiguity parameters solved by the low-orbit satellite system observation model at a previous epoch.

[0044] Optionally, the acquisition module obtains a complete upper bound covariance matrix of the low-orbit satellite system observation model according to the first upper bound covariance matrix and the second upper bound covariance matrix, including:

[0045] ;

[0046] in, represents the complete upper bound covariance matrix; represents the first upper bound covariance matrix; represents the second upper bound covariance matrix; It represents the operation of forming a block diagonal matrix with the matrix in brackets; Represents the current epoch.

[0047] Optional, upper bound form covariance matrix calculation module, specifically used to perform the following calculations:

[0048] ;

[0049] in, represents the upper bound form covariance matrix; Represents the transpose operation of a matrix; express The design matrix below; , express The design matrix corresponding to the observation equation under ; express The design matrix corresponding to the time constraint equation below.

[0050] Optionally, an impact determination module is used to:

[0051] Get to The deviation of the deviation in the filter solution is The influence of unknown parameters in ;in, represents the first epoch, Indicates the current epoch the previous epoch of The influences corresponding to the clock error and the orbital parameter are extracted respectively, and a first influence of the deviation transfer on the clock error and a second influence of the deviation transfer on the orbital parameter are obtained.

[0052] Optional integrity monitoring module, specifically used for:

[0053] The first protection level is compared with a preset low-orbit satellite clock error alarm threshold, and the second protection level is compared with a preset low-orbit satellite orbit error alarm threshold, and an alarm is issued when the first protection level exceeds the low-orbit satellite clock error alarm threshold and / or the second protection level exceeds the low-orbit satellite orbit error alarm threshold.

[0054] Optionally, the protection level determination module obtains a first protection level according to the first upper bound formal standard deviation and the first impact, including:

[0055] ;

[0056] in, Indicates the first protection level; represents the calculation factor; represents the standard deviation of the first upper bound form; represents the first impact; Represents the current epoch.

[0057] Optionally, the protection level determination module obtains the second protection level according to the second upper bound formal standard deviation and the second impact, including:

[0058] ;

[0059] in, Indicates the second level of protection; represents the calculation factor; represents the second upper bound form standard deviation; represents the second impact; Represents the current epoch.

[0060] In a method for monitoring the integrity of real-time filtering timing and orbit determination of a low-orbit satellite provided by the present invention, first, according to the corresponding elements in the covariance matrix of the upper bound form of unknown parameters of the clock error and the orbit parameter in the observation model of the low-orbit satellite system, the first upper bound form standard deviation of the clock error and the second upper bound form standard deviation of the orbit parameter are obtained, and then the first influence of the deviation transfer on the clock error and the second influence on the orbit parameter are obtained through the deviation transfer of multiple epochs, and then the first protection level is obtained according to the first upper bound form standard deviation and the first influence, and the second protection level is obtained according to the second upper bound form standard deviation and the second influence, and the integrity monitoring of the real-time filtering timing and orbit determination of the low-orbit satellite is performed based on the first protection level and the second protection level. In this way, in the integrity monitoring of the real-time filtering timing and orbit determination of the low-orbit satellite based on the first protection level and the second protection level, the protection level is calculated by introducing the influence of the deviation transfer on the clock error and the orbit parameter, so as to further improve the accuracy of the integrity monitoring.

[0061] The present invention will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 It is a flow chart of a method for monitoring the integrity of real-time filtering timing and orbit determination of a low-orbit satellite provided by an embodiment of the present invention;

[0063] Figure 2 It is a structural schematic diagram of a low-orbit satellite real-time filtering timing and orbit determination integrity monitoring device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0064] The present invention is further described in detail below with reference to specific embodiments, but the embodiments of the present invention are not limited thereto.

[0065] The existing integrity monitoring method mainly relies on the integrity risk given in advance to calculate the protection level of the aircraft positioning result, resulting in low integrity monitoring accuracy. In order to solve this problem, the embodiment of the present invention provides a low-orbit satellite real-time filtering timing and orbit determination integrity monitoring method, see Figure 1 , Figure 1 1 is a flow chart of a method for monitoring the integrity of a low-orbit satellite real-time filtering timing and orbit determination provided by an embodiment of the present invention, which specifically includes the following steps:

[0066] Step S101, obtaining the complete upper bound covariance matrix of the low-orbit satellite system observation model of the current epoch.

[0067] In the embodiment of the present invention, the epoch is a specific time specified for specifying celestial coordinates or orbital parameters. A low-orbit satellite system refers to a satellite operating in a low orbit, such as some earth observation satellites or communication satellites. An observation model refers to a satellite carrier phase and pseudorange observation model.

[0068] In an embodiment of the present invention, the complete upper bound covariance matrix is ​​a covariance matrix containing all relevant parameters of the low-orbit satellite system observation model at the current epoch. The covariance matrix can be used to describe the relationship between multiple random variables.

[0069] Step S102, calculating the upper bound form covariance matrix of unknown parameters in the low-orbit satellite system observation model according to the complete upper bound covariance matrix; the unknown parameters include clock errors and orbital parameters.

[0070] In an embodiment of the present invention, the upper bound form covariance matrix of the unknown parameters in the low-orbit satellite system observation model can be calculated based on the complete upper bound covariance matrix containing the unknown parameters of the low-orbit satellite system observation model. The upper bound form covariance matrix describes the uncertainty of each unknown parameter and the correlation between them, and its diagonal elements give the variance of each unknown parameter, and the standard deviation of each unknown parameter can be obtained by the square root.

[0071] Specifically, the unknown parameters may include clock error and orbital parameters. The clock error is the difference between the low-orbit satellite system clock and the universal time, and the orbital parameters are used to describe the position and motion state of the satellite in its orbit.

[0072] Step S103, obtaining the first upper bound form standard deviation of the clock error and the second upper bound form standard deviation of the orbital parameter according to the corresponding elements in the upper bound form covariance matrix of the clock error and the orbital parameter.

[0073] In the embodiment of the present invention, the first upper bound form standard deviation refers to the standard deviation related to the clock error, which is calculated from the diagonal elements corresponding to the clock error in the upper bound form covariance matrix and is used to indicate the degree of uncertainty of the clock error.

[0074] In an embodiment of the present invention, the second upper bound form standard deviation refers to the standard deviation related to the orbital parameters, which is calculated from the diagonal elements corresponding to the orbital parameters in the upper bound form covariance matrix and is used to indicate the degree of uncertainty of the orbital parameters.

[0075] Step S104, determining a first impact of the bias transfer of multiple epochs on the clock error and a second impact of the bias transfer on the orbital parameters.

[0076] In the embodiment of the present invention, the upper bound deviation caused by the real-time GNSS orbit satellite clock combination error of each epoch is , including the upper bound deviation vector of SISRE (space signal ranging error) of each low-orbit satellite system , which acts on the ionosphere-free combination of carrier phase observation and pseudorange observation in the low-orbit satellite system observation model of all epochs, will affect the unknown parameters in the low-orbit satellite system observation model of each epoch, and transfer to the next epoch through ambiguity parameters, which is called bias transfer. The unknown parameters include clock errors and orbital parameters. Among them, , is the total number of systems.

[0077] Specifically, as in the first epoch It will affect the unknown parameters in the low-orbit satellite system observation model of all subsequent epochs. It will also affect the unknown parameters in the low-orbit satellite system observation model of all subsequent epochs until the epoch It will also The unknown parameters in the low-orbit satellite system observation model of the current epoch are affected. After derivation, the unknown parameters under each epoch can be obtained. In the The maximum sum of the influences of the epochs on the unknown parameters in the observation model of the low-orbit satellite system. Then, according to the elements corresponding to the clock error and orbital parameters in the maximum sum, the first influence of the bias transfer of multiple epochs on the clock error and the second influence of the bias transfer on the orbital parameters can be obtained.

[0078] Step S105, obtaining a first protection level according to the first upper bound form standard deviation and the first impact, and obtaining a second protection level according to the second upper bound form standard deviation and the second impact.

[0079] In the embodiment of the present invention, the protection level is the main indicator for integrity monitoring, wherein the first upper limit form standard deviation and the first influence are the upper limit form standard deviation and influence corresponding to the clock error, so the first protection level is an indicator for monitoring the clock error; the second upper limit form standard deviation and the second influence are the upper limit form standard deviation and influence corresponding to the orbit parameter, so the second protection level is an indicator for monitoring the orbit error. By combining the first protection level and the second protection level, the integrity of the real-time filtering timing and orbit determination of the low-orbit satellite can be monitored.

[0080] Step S106: Perform integrity monitoring of low-orbit satellite real-time filtering timing and orbit determination based on the first protection level and the second protection level.

[0081] In the embodiment of the present invention, integrity monitoring refers to ensuring the reliability of data related to the low-orbit satellite system by real-time monitoring of the performance and status of the low-orbit satellite system. The goal of integrity monitoring is to promptly issue an alarm when an abnormality occurs in the low-orbit satellite real-time orbit determination and timing system to prevent users from relying on erroneous information.

[0082] The protection level is the main indicator for integrity monitoring. Therefore, through the first and second protection levels, the clock error and orbit parameters of the low-orbit satellite system can be detected in real time to ensure the safety and accuracy of the low-orbit satellite real-time orbit determination and timing system.

[0083] In an embodiment of the present invention, first, the first upper bound form standard deviation of the clock error and the second upper bound form standard deviation of the orbit parameter are obtained according to the corresponding elements in the covariance matrix of the upper bound form of the unknown parameters in the low-orbit satellite system observation model of the clock error and the orbit parameter, and then the first influence of the deviation transfer on the clock error and the second influence on the orbit parameter are obtained through the deviation transfer of multiple epochs, and then the first protection level is obtained according to the first upper bound form standard deviation and the first influence, and the second protection level is obtained according to the second upper bound form standard deviation and the second influence, and the integrity monitoring of the low-orbit satellite real-time filtering timing and orbit determination is performed based on the first protection level and the second protection level. In this way, in the integrity monitoring of the low-orbit satellite real-time filtering timing and orbit determination based on the first protection level and the second protection level, the protection level is calculated by introducing the influence of the deviation transfer on the clock error and orbit parameters, so as to further improve the accuracy of the integrity monitoring.

[0084] In one implementation, obtaining a complete upper bound covariance matrix of a low-orbit satellite system observation model at a current epoch includes:

[0085] (1) Determine the first upper bound covariance matrix of the ionosphere-free combination of carrier phase observations and pseudorange observations of the low-orbit satellite system observation model at the current epoch;

[0086] (2) In the GNSS system, the ambiguity parameters are solved by the low-orbit satellite system observation model in each epoch. Therefore, the second upper-bound covariance matrix can be obtained here by the upper-bound covariance matrix of the ambiguity parameters with time constraints between the previous epoch and the current epoch. The upper-bound covariance matrix of the ambiguity parameters is obtained by the upper-bound covariance matrix of the ambiguity parameters solved by the low-orbit satellite system observation model in the previous epoch.

[0087] (3) According to the first upper bound covariance matrix and the second upper bound covariance matrix, the complete upper bound covariance matrix of the low-orbit satellite system observation model is obtained.

[0088] Specifically, before determining the first upper bound covariance matrix of the ionosphere-free combination of the carrier phase observation and the pseudorange observation of the low-orbit satellite system observation model at the current epoch, the noise and bias related parameters related to the low-orbit satellite system observation model are first determined.

[0089] In the embodiment of the present invention, the carrier phase and pseudo-range observation noise, and the multipath effect of low-orbit satellite in an open environment are characterized as noise, and the upper standard deviation is and The specific value can be defined based on empirical data. The GNSS real-time orbit clock error is characterized as noise and bias. The upper standard deviation of SISRE is determined based on empirical data using a two-step method. and upper bound deviation .

[0090] Then, the first upper bound covariance matrix of the ionosphere-free combination of carrier phase observation and pseudorange observation of the low-orbit satellite system observation model at the current epoch for integrity calculation is constructed through the noise and bias-related parameters related to the low-orbit satellite system observation model determined above, and its expression is:

[0091] ;

[0092] in, express The first upper bound covariance matrix when ; It represents the operation of forming a block diagonal matrix with the matrix in brackets; Next The weight matrix related to the elevation angle of all observed GNSS satellites in a GNSS system is used express; Indicates the current epoch; is the ionospheric-free combined expansion factor of the carrier phase observation and pseudorange observation at the current epoch; Indicates The first upper bound standard deviation of the carrier phase of the GNSS system; Indicates The second upper bound standard deviation of the pseudorange observations of the GNSS system; Indicates The upper bound standard deviation of the GNSS real-time orbit satellite clock SISRE of each GNSS system; ; is the total number of GNSS systems used.

[0093] After obtaining the first upper bound covariance matrix, the inter-epoch time constraints of the integer ambiguity parameters in the filter are considered in the sequential least squares method. The second upper bound covariance matrix of the time constraint equation is obtained, thereby obtaining the complete upper bound covariance matrix of the low-orbit satellite system observation model when solving the epoch .

[0094] In an embodiment of the present invention, a second upper bound covariance matrix is ​​obtained by using an upper bound covariance matrix of ambiguity parameters with time constraints between the previous epoch and the current epoch; wherein the upper bound covariance matrix of ambiguity parameters is obtained by using an upper bound covariance matrix of ambiguity parameters solved by an observation model of a low-orbit satellite system in the previous epoch.

[0095] The calculation method of the second upper bound covariance matrix includes:

[0096] ;

[0097] in, express The upper bound form of the lower unknown parameters is the covariance matrix; Indicated in The unknown parameters are Matrix for selecting fuzzy parameters with time constraints.

[0098] In the embodiment of the present invention, the complete upper bound covariance matrix of the low-orbit satellite system observation model is obtained according to the first upper bound covariance matrix and the second upper bound covariance matrix. The calculation methods include:

[0099] ;

[0100] in, represents the second upper bound covariance matrix; represents the first upper bound covariance matrix; Indicates the current epoch.

[0101] In one implementation, the upper bound form covariance matrix of unknown parameters in the low-orbit satellite system observation model is calculated based on the complete upper bound covariance matrix, including:

[0102] ;

[0103] in, represents the upper bound form covariance matrix; Represents the transpose operation of a matrix; express The design matrix below; , express The design matrix corresponding to the observation equation under ; express The design matrix corresponding to the time constraint equation under the epoch.

[0104] On this basis, and Depend on The elements corresponding to the clock error and orbital parameters are obtained by taking the square root.

[0105] In one implementation, determining a first effect of bias transfer on a clock error and a second effect of bias transfer on an orbit parameter for a plurality of epochs includes:

[0106] (1) Obtain to The noise and deviation of the deviation transfer in the filtering solution The influence of unknown parameters in ;in, represents the first epoch, Indicates the current epoch the previous epoch of ;

[0107] (2) From The corresponding influences of clock error and orbital parameters are extracted from the paper, and the first influence of deviation transfer on clock error and the second influence of deviation transfer on orbital parameters are obtained.

[0108] The following will to The noise and deviation are solved in the filter, that is, the deviation transfer in the filter The influence of unknown parameters in The specific calculation process is described in detail:

[0109] In the first epoch The initial impact on the unknown parameters can be expressed as :

[0110] ;

[0111] in, express The projection matrix of the observation domain to the result domain under is equal to ; express The design matrix corresponding to the observation equation under ; Indicates the initialization of the GNSS system , the number of its elements is equal to the number of observations, and each element corresponds to the upper bound deviation of the GNSS system SISRE where the corresponding observation satellite is located.

[0112] In the filter, the blur parameter Transfer, yes The influence of unknown parameters in It can be expressed as:

[0113] ;

[0114] in, express The projection matrix of the observation domain to the result domain corresponding to the time constraint equation under is equal to The rows in that correspond to the time constraint equations; express The design matrix corresponding to the time constraint equation below; Indicated in The unknown parameters of Matrix for selecting fuzzy parameters with time constraints.

[0115] And so on. Upper bound deviation vector of the lower LEO satellite system right The influence of unknown parameters for:

[0116] ;

[0117] in, express The projection matrix of the observation domain to the result domain corresponding to the time constraint equation under is equal to The rows in that correspond to the time constraint equations; express The design matrix corresponding to the time constraint equation below; Indicated in The unknown parameters are Matrix for selecting fuzzy parameters with time constraints; express Deviation The influence of unknown parameters; Indicates from 1 to Variables; express The projection matrix of the observation domain to the result domain corresponding to the time constraint equation under is equal to The rows in that correspond to the time constraint equations; express The design matrix corresponding to the time constraint equation below; Indicated in The unknown parameters are Matrix for selecting fuzzy parameters with time constraints.

[0118] Considering that the actual deviation may be positive or negative, The upper bound deviation vector right The maximum influence of the unknown parameters under :

[0119] ;

[0120] time, except outside, The filter will have such an impact on the unknown parameters. Therefore, the noise and deviation at each epoch are The maximum sum of the unknown parameters for:

[0121] ;

[0122] in, express The projection matrix from the observation domain to the result domain; Indicates Bias transfer pairs The influence of unknown parameters of the epoch can be expressed as:

[0123] ;

[0124] Considering the computational efficiency, After the deviation transfer in the expression converges to a certain time, its transfer effect can be ignored, that is, when Reach a certain threshold back, The calculation of .

[0125] In getting After that, the effect of deviation transfer on clock error and orbit parameters is The elements corresponding to the clock error and orbital parameters are and .

[0126] In one implementation, integrity monitoring of real-time filtering timing and orbit determination of a low-orbit satellite is performed based on the first protection level and the second protection level, including:

[0127] The first protection level is compared with the preset low-orbit satellite clock error alarm threshold, and the second protection level is compared with the preset low-orbit satellite orbit error alarm threshold, and an alarm is issued when the first protection level exceeds the low-orbit satellite clock error alarm threshold and / or the second protection level exceeds the low-orbit satellite orbit error alarm threshold.

[0128] In the embodiment of the present invention, the low-orbit satellite clock error alarm threshold Refers to the maximum tolerance of the pre-set clock error. Low-orbit satellite orbit error alarm threshold Refers to the maximum tolerance value of the pre-set orbit error.

[0129] When the first protection level exceeds the low-orbit satellite clock error alarm threshold and / or the second protection level exceeds the low-orbit satellite orbit error alarm threshold, an alarm is issued specifically in the following situations:

[0130] If the value of the first protection level exceeds the low-orbit satellite clock error alarm threshold, and the value of the second protection level does not exceed the low-orbit satellite orbit error alarm threshold, it means that the satellite clock performs abnormally and triggers an alarm related to the satellite clock.

[0131] If the value of the second protection level exceeds the low-orbit satellite orbit error alarm threshold, and the value of the first protection level does not exceed the low-orbit satellite clock error alarm threshold, it means that the orbit performance is abnormal and triggers an alarm corresponding to the orbit.

[0132] If the value of the first protection level exceeds the low-orbit satellite clock error alarm threshold, and the second protection level exceeds the low-orbit satellite orbit error alarm threshold, it means that both the satellite clock and the orbit are abnormal, triggering alarms related to the satellite clock and alarms corresponding to the orbit.

[0133] In the process of monitoring the integrity of the real-time filtering timing and orbit determination of low-orbit satellites, after an alarm occurs, relevant technical personnel can take corresponding measures and carry out relevant processing based on the specific alarm information.

[0134] Specifically, the clock error alarm threshold and the orbit error alarm threshold can be pre-set by technical personnel based on experience and are not limited here.

[0135] In one implementation, obtaining a first protection level according to a first upper bound form standard deviation and a first impact includes:

[0136] ;

[0137] in, Indicates the first protection level; represents the calculation factor; represents the first upper bound form standard deviation; Indicates the first impact.

[0138] In one implementation, obtaining a second protection level according to a second upper bound form standard deviation and a second impact includes:

[0139] ;

[0140] Indicates the second level of protection; represents the calculation factor; represents the second upper bound form standard deviation; Indicates the second impact.

[0141] in, The factor can be calculated based on the integrity risk and the inverse cumulative distribution function of the standard normal distribution The calculation results are:

[0142] ;

[0143] in, Indicates integrity risk.

[0144] Based on the same inventive concept, the embodiment of the present invention also provides a low-orbit satellite real-time filtering timing and orbit determination integrity monitoring device, see Figure 2 , Figure 2 1 is a schematic diagram of the structure of a low-orbit satellite real-time filtering timing and orbit determination integrity monitoring device provided by an embodiment of the present invention, the integrity monitoring device comprising:

[0145] An acquisition module 201 is used to acquire a complete upper bound covariance matrix of a low-orbit satellite system observation model at a current epoch;

[0146] The upper bound form covariance matrix calculation module 202 is used to calculate the upper bound form covariance matrix of unknown parameters in the low-orbit satellite system observation model according to the complete upper bound covariance matrix; the unknown parameters include clock errors and orbital parameters;

[0147] A standard deviation determination module 203 is used to obtain a first upper bound form standard deviation of the clock error and a second upper bound form standard deviation of the orbit parameter according to corresponding elements of the clock error and the orbit parameter in the upper bound form covariance matrix;

[0148] An impact determination module 204, configured to determine a first impact of bias transfer of a plurality of epochs on the clock error and a second impact of bias transfer on the orbital parameters;

[0149] A protection level determination module 205, configured to obtain a first protection level according to a first upper bound form standard deviation and a first impact, and to obtain a second protection level according to a second upper bound form standard deviation and a second impact;

[0150] The integrity monitoring module 206 is used to perform integrity monitoring of real-time filtering timing and orbit determination of low-orbit satellites based on the first protection level and the second protection level.

[0151] In an embodiment of the present invention, first, the first upper bound form standard deviation of the clock error and the second upper bound form standard deviation of the orbit parameter are obtained according to the corresponding elements in the covariance matrix of the upper bound form of the unknown parameters in the low-orbit satellite system observation model of the clock error and the orbit parameter, and then the first influence of the deviation transfer on the clock error and the second influence on the orbit parameter are obtained through the deviation transfer of multiple epochs, and then the first protection level is obtained according to the first upper bound form standard deviation and the first influence, and the second protection level is obtained according to the second upper bound form standard deviation and the second influence, and the integrity monitoring of the low-orbit satellite real-time filtering timing and orbit determination is performed based on the first protection level and the second protection level. In this way, in the integrity monitoring of the low-orbit satellite real-time filtering timing and orbit determination based on the first protection level and the second protection level, the protection level is calculated by introducing the influence of the deviation transfer on the clock error and orbit parameters, so as to further improve the accuracy of the integrity monitoring.

[0152] Optional, get module, specifically used for:

[0153] Determine the first upper bound covariance matrix of the ionosphere-free combination of carrier phase observations and pseudorange observations of the low-orbit satellite system observation model in the current epoch; obtain the second upper bound covariance matrix through the upper bound covariance matrix of the ambiguity parameters with time constraints between the previous epoch and the current epoch; obtain the complete upper bound covariance matrix of the low-orbit satellite system observation model according to the first upper bound covariance matrix and the second upper bound covariance matrix; the upper bound covariance matrix of the ambiguity parameters is obtained by the upper bound covariance matrix of the ambiguity parameters solved by the low-orbit satellite system observation model in the previous epoch.

[0154] Optionally, the acquisition module obtains a complete upper bound covariance matrix of the low-orbit satellite system observation model according to the first upper bound covariance matrix and the second upper bound covariance matrix, including:

[0155] ;

[0156] in, represents the complete upper bound covariance matrix; represents the first upper bound covariance matrix; represents the second upper bound covariance matrix; It represents the operation of forming a block diagonal matrix with the matrix in brackets; Indicates the current epoch.

[0157] Optional, upper bound form covariance matrix calculation module, specifically used to perform the following calculations:

[0158] ;

[0159] in, represents the upper bound form covariance matrix; Represents the transpose operation of a matrix; express The design matrix below; , express The design matrix corresponding to the observation equation under ; express The design matrix corresponding to the time constraint equation below.

[0160] Optionally, an impact determination module is used to:

[0161] Get to The deviation of the deviation in the filter solution is The influence of unknown parameters in ;in, represents the first epoch, Indicates the current epoch the previous epoch of The corresponding influences of clock error and orbital parameters are extracted from the paper, and the first influence of deviation transfer on clock error and the second influence of deviation transfer on orbital parameters are obtained.

[0162] Optional integrity monitoring module, specifically used for:

[0163] The first protection level is compared with the preset low-orbit satellite clock error alarm threshold, and the second protection level is compared with the preset low-orbit satellite orbit error alarm threshold, and an alarm is issued when the first protection level exceeds the low-orbit satellite clock error alarm threshold and / or the second protection level exceeds the low-orbit satellite orbit error alarm threshold.

[0164] Optionally, the protection level determination module obtains the first protection level according to the first upper bound formal standard deviation and the first impact, including:

[0165] ;

[0166] in, Indicates the first protection level; represents the calculation factor; represents the first upper bound form standard deviation; Indicates the first impact; Indicates the current epoch.

[0167] Optionally, the protection level determination module obtains the second protection level according to the second upper bound formal standard deviation and the second impact, including:

[0168] ;

[0169] in, Indicates the second level of protection; represents the calculation factor; represents the second upper bound form standard deviation; Indicates the second influence; Indicates the current epoch.

[0170] It should be noted that the terms "first", "second", etc. are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Instead, they are merely examples of devices and methods consistent with some aspects of the present invention.

[0171] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification.

[0172] Although the present invention is described herein in conjunction with various embodiments, in the process of implementing the claimed invention, those skilled in the art can understand and implement other changes to the disclosed embodiments by viewing the drawings and the disclosed content. In the description of the present invention, the term "comprising" does not exclude other components or steps, "one" or "an" does not exclude multiple situations, and "multiple" means two or more, unless otherwise clearly and specifically limited. In addition, certain measures are recorded in different embodiments, but this does not mean that these measures cannot be combined to produce good results.

[0173] As for the device embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0174] It should be noted that the device of an embodiment of the present invention is a device that applies the above-mentioned method for monitoring the integrity of real-time filtering, timing and orbit determination of low-orbit satellites. All embodiments of the above-mentioned method for monitoring the integrity of real-time filtering, timing and orbit determination of low-orbit satellites are applicable to the device and can achieve the same or similar beneficial effects.

[0175] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A method for monitoring the integrity of real-time filtering timing and orbit determination of low-orbit satellites, characterized in that: include: Get the complete upper bound covariance matrix of the low-orbit satellite system observation model for the current epoch; Calculate the upper bound form covariance matrix of unknown parameters in the low-orbit satellite system observation model according to the complete upper bound covariance matrix; the unknown parameters include clock errors and orbital parameters; Obtaining a first upper bound form standard deviation of the clock error and a second upper bound form standard deviation of the orbital parameter according to corresponding elements of the clock error and the orbital parameter in the upper bound form covariance matrix; Determining a first effect of bias propagation for a plurality of epochs on the clock error and a second effect of the bias propagation on the orbital parameters; Obtaining a first protection level according to the first upper bound formal standard deviation and the first impact, and obtaining a second protection level according to the second upper bound formal standard deviation and the second impact; Based on the first protection level and the second protection level, integrity monitoring of real-time filtering timing and orbit determination of low-orbit satellites is performed.

2. The integrity monitoring method according to claim 1, characterized in that: Get the complete upper bound covariance matrix of the low-orbit satellite system observation model for the current epoch, including: Determine a first upper bound covariance matrix of an ionospheric-free combination of carrier phase observations and pseudorange observations of a low-orbit satellite system observation model at a current epoch; A second upper bound covariance matrix is ​​obtained by using an upper bound covariance matrix of ambiguity parameters with time constraints between the previous epoch and the current epoch; the upper bound covariance matrix of the ambiguity parameters is obtained by using an upper bound covariance matrix of ambiguity parameters solved by the low-orbit satellite system observation model in the previous epoch; A complete upper bound covariance matrix of the low-orbit satellite system observation model is obtained according to the first upper bound covariance matrix and the second upper bound covariance matrix.

3. The integrity monitoring method according to claim 2, characterized in that: Obtaining a complete upper bound covariance matrix of the low-orbit satellite system observation model according to the first upper bound covariance matrix and the second upper bound covariance matrix, including: ； in, represents the complete upper bound covariance matrix; represents the first upper bound covariance matrix; represents the second upper bound covariance matrix; It represents the operation of forming a block diagonal matrix with the matrix in brackets; Represents the current epoch.

4. The integrity monitoring method according to claim 3, characterized in that: Calculating the upper bound form covariance matrix of unknown parameters in the low-orbit satellite system observation model according to the complete upper bound covariance matrix includes: ； in, represents the upper bound form covariance matrix; Represents the transpose operation of a matrix; express The design matrix below; , express The design matrix corresponding to the observation equation under ; express The design matrix corresponding to the time constraint equation below.

5. The integrity monitoring method according to claim 1, characterized in that: Determining a first effect of bias propagation of a plurality of epochs on the clock error and a second effect of the bias propagation on the orbital parameters comprises: Get to The deviation of the deviation in the filter solution is The influence of unknown parameters in ;in, represents the first epoch, Indicates the current epoch the previous epoch of ; from The influences corresponding to the clock error and the orbital parameter are extracted respectively, and a first influence of the deviation transfer on the clock error and a second influence of the deviation transfer on the orbital parameter are obtained.

6. The integrity monitoring method according to claim 1, characterized in that: Based on the first protection level and the second protection level, integrity monitoring of real-time filtering timing and orbit determination of low-orbit satellites is performed, including: The first protection level is compared with a preset low-orbit satellite clock error alarm threshold, and the second protection level is compared with a preset low-orbit satellite orbit error alarm threshold, and an alarm is issued when the first protection level exceeds the low-orbit satellite clock error alarm threshold and / or the second protection level exceeds the low-orbit satellite orbit error alarm threshold.

7. The integrity monitoring method according to claim 1, characterized in that: Obtaining a first protection level according to the first upper bound formal standard deviation and the first impact includes: ； in, Indicates the first protection level; represents the calculation factor; represents the standard deviation of the first upper bound form; represents the first impact; Represents the current epoch.

8. The integrity monitoring method according to claim 1, characterized in that: Obtaining a second protection level according to the second upper bound form standard deviation and the second impact includes: ； in, Indicates the second level of protection; represents the calculation factor; represents the second upper bound form standard deviation; represents the second impact; Represents the current epoch.

9. A low-orbit satellite real-time filtering timing and orbit determination integrity monitoring device, characterized in that: include: An acquisition module is used to obtain the complete upper bound covariance matrix of the low-orbit satellite system observation model of the current epoch; An upper bound form covariance matrix calculation module is used to calculate the upper bound form covariance matrix of unknown parameters in the low-orbit satellite system observation model according to the complete upper bound covariance matrix; the unknown parameters include clock errors and orbital parameters; A standard deviation determination module, used for obtaining a first upper bound form standard deviation of the clock error and a second upper bound form standard deviation of the orbit parameter according to corresponding elements of the clock error and the orbit parameter in the upper bound form covariance matrix; An impact determination module, configured to determine a first impact of bias transfer of a plurality of epochs on the clock error and a second impact of the bias transfer on the orbital parameter; a protection level determination module, configured to obtain a first protection level according to the first upper bound formal standard deviation and the first impact, and to obtain a second protection level according to the second upper bound formal standard deviation and the second impact; An integrity monitoring module is used to perform integrity monitoring of real-time filtering timing and orbit determination of low-orbit satellites based on the first protection level and the second protection level.

10. The integrity monitoring device according to claim 9, characterized in that: The acquisition module is specifically used for: Determine a first upper bound covariance matrix of an ionosphere-free combination of carrier phase observations and pseudorange observations of a low-orbit satellite system observation model at a current epoch; obtain a second upper bound covariance matrix through an upper bound covariance matrix of ambiguity parameters with time constraints between a previous epoch and a current epoch; obtain a complete upper bound covariance matrix of the low-orbit satellite system observation model according to the first upper bound covariance matrix and the second upper bound covariance matrix; the upper bound covariance matrix of the ambiguity parameters is obtained by an upper bound covariance matrix of the ambiguity parameters solved by the low-orbit satellite system observation model at a previous epoch.

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