Filtering positioning method and system for single-frequency user of Beidou satellite-based enhancement system

Abstract

The invention discloses a filtering positioning method for a single-frequency user of a Beidou satellite-based enhancement system, and relates to the satellite navigation positioning technology, and the method comprises the steps: obtaining pseudo-range observation values, carrier phase observation values, navigation messages and BDSBAS single-frequency enhancement messages of N GPS satellites at a current moment tk, and obtaining a user state variable estimation value and a covariance matrix of the user state variable estimation value at a previous moment tk-1; carrier phase smoothing pseudo-range measurement at the current moment tk is constructed; according to the constructed carrier phase smooth pseudo-range measurement, calculating the corrected orbit and clock error parameters of the tkGPS satellite at the current moment; the troposphere delay error and the ionosphere delay error at the current moment tk are calculated, and the satellite pseudo-range measurement error at the current moment tk is corrected; and estimating the position parameter of the user at the current moment tk based on Kalman filtering. According to the method, the high-frequency component in the positioning error can be effectively suppressed, and the user positioning precision is remarkably improved.

Description

Technical Field

[0001] The present application relates to the field of satellite navigation and positioning technology, and in particular to a filtering positioning method and system for single-frequency users of a Beidou satellite-based augmentation system. Background Art

[0002] The BeiDou Satellite Based Augmentation System (BDSBAS) realizes independent integrity monitoring of visible Global Navigation Satellite System (GNSS) satellites through widely distributed monitoring stations. It complies with relevant ICAO standards and can provide integrity services for high-life safety users represented by civil aviation.

[0003] The Beidou Satellite-Based Augmentation System broadcasts single-frequency augmentation messages through the B1C frequency of the SBAS GEO (Geosynchronous Earth Orbit) satellite. The messages contain the orbit / clock correction number of the augmented satellite, the grid ionospheric delay correction number (GIVD), the user ranging error index (UDREI), the grid ionospheric error index (GIVEI), the degradation parameters and other integrity parameters. Civil aviation users perform error correction and least squares solution according to the methods specified in RTCA DO-229E and the national standard GB / T 42832.1-2023 to obtain the user's enhanced positioning position and protection level.

[0004] The B1C single-frequency augmentation message of the Beidou Satellite-Based Augmentation System is broadcast over a wide area. In addition to civil aviation users, users in other industries can also receive and use the public messages. Using the BDSBAS B1C single-frequency augmentation message and the least squares positioning method specified in DO-229F issued by the International Civil Aviation Organization can improve the user positioning accuracy to a certain extent. However, it belongs to a single epoch solution. During the calculation process, the current epoch cannot inherit the information of the previous epoch. The positioning results of each epoch are independent of each other, and there are a large number of high-frequency errors that affect the user positioning accuracy.

[0005] At present, the BDSBAS B1C single-frequency enhanced positioning method specified in RTCA DO-229E is a least squares positioning algorithm suitable for civil aviation users. The least squares positioning algorithm belongs to single-epoch solution, and the solution epoch cannot inherit the positioning information of the previous epoch. The positioning error contains a large number of high-frequency errors, and the accuracy improvement is limited. It cannot meet the needs of other industries for high-precision positioning, which restricts the application and promotion of BDSBAS B1C single-frequency services. Summary of the invention

[0006] The embodiment of the present application provides a filtering positioning method and system for single-frequency users of the Beidou Satellite-Based Augmentation System, which is used to introduce a Kalman filtering method into the BDSBAS B1C single-frequency enhanced positioning method to achieve the integration of the previous and next epochs of the positioning information, which can effectively suppress the high-frequency components in the positioning error and significantly improve the user positioning accuracy.

[0007] The present application embodiment provides a filtering positioning method for a single-frequency user of a Beidou satellite-based augmentation system, including:

[0008] Get the current time t k The pseudo-range observation values ​​and carrier phase observation values ​​of N GPS satellites, navigation messages, BDSBAS single-frequency enhancement messages, and the last time t k-1 The estimated values ​​of the user state variables and their covariance matrix;

[0009] Construct the current time t k Carrier phase smoothed pseudorange measurement;

[0010] According to the constructed carrier phase smoothed pseudorange measurement, calculate the current time t k Corrected orbit and clock parameters of GPS satellites; and,

[0011] Calculate the current time t k The tropospheric delay error and ionospheric delay error of the current time t k Correction of satellite pseudorange measurement errors;

[0012] Estimate the current time t based on Kalman filtering k The user's position parameters.

[0013] Optionally, construct the current time t k The carrier phase smoothed pseudorange measurement includes:

[0014] The carrier phase smoothed pseudorange measurements are calculated as follows:

[0015]

[0016] In the formula, represents the current time t k Carrier phase smoothed pseudorange measurement of satellite i; represents the current time t k is the original pseudorange measurement of star i at the current moment; Indicates t k-1 The original pseudorange measurement of satellite i at time i; Yes k Carrier phase measurement of satellite i at time i; Yes k-1The carrier phase measurement of satellite i at time λ is the wavelength of the signal corresponding to the frequency point, and τ is the smoothing time.

[0017] Optionally, the current time t is calculated based on the constructed carrier phase smoothed pseudorange measurement k The corrected orbit and clock parameters of GPS satellites include:

[0018] Use GPS L1C / A frequency navigation message to calculate GPS satellite orbit clock error parameters;

[0019] The BDSBAS B1C single-frequency augmentation message is parsed to obtain the augmented GPS satellite orbit / clock error correction number, and the satellite orbit and clock error are corrected.

[0020] Optionally, calculate the current time t k The tropospheric delay errors include:

[0021] Using the tropospheric delay error model, calculate the tropospheric delay error of satellite i To correct the carrier phase smoothed pseudorange.

[0022] Optionally, calculate the current time t k The ionospheric delay errors include:

[0023] Calculate the ionospheric delay error of satellite i using the ionospheric model parameters broadcast in the navigation message

[0024] Optionally, for the current time t k The satellite pseudorange measurement error correction includes:

[0025] The smoothed pseudorange measurement values ​​are corrected for tropospheric and ionospheric errors to meet the following requirements:

[0026]

[0027] in, Represents the error correction for the troposphere and ionosphere.

[0028] Optionally, the current time t is estimated based on Kalman filtering k The user's location parameters include:

[0029] Predicting state variables:

[0030]

[0031] in, is the current time t k The predicted value of the user state variable, is the previous time t k-1 The estimated value of the user state variable, By t k-1 to k The state transfer matrix is ​​as follows:

[0032]

[0033] Prediction covariance:

[0034]

[0035] in, is the current time t k The predicted value of the user state variable covariance matrix, is the previous time t k-1 The covariance matrix of the estimated values ​​of the user state variables, is the noise variance matrix of the state transfer process, t is t k-1 to k time difference;

[0036] Calculate the filter gain matrix to satisfy:

[0037]

[0038] in, is the current time t k The Kalman filter gain matrix, is the design matrix of the measurement equation, is the measurement noise variance matrix of the measurement equation;

[0039] Defining the Design Matrix satisfy:

[0040]

[0041] in, is the unit direction vector from satellite i to user receiver R,

[0042] The estimated state parameters satisfy:

[0043]

[0044] in, is the estimated current time t k The estimated value of the user state variable, is the current time t k The observation vector, the observation vector satisfy:

[0045]

[0046] Optionally, the method further includes: outputting a user position estimate and performing subsequent epoch estimation.

[0047] An embodiment of the present application also proposes a filtering positioning system for single-frequency users of a Beidou satellite-based augmentation system, including a processor and a memory, wherein a computer program is stored in the memory, and when the computer program is executed by the processor, the steps of the filtering positioning method for single-frequency users of the Beidou satellite-based augmentation system as described above are implemented.

[0048] The method of the embodiment of the present application introduces a Kalman filtering method into the BDSBAS B1C single-frequency enhanced positioning method to achieve the integration of the previous and next epochs of the positioning information, which can effectively suppress the high-frequency components in the positioning error and significantly improve the user positioning accuracy.

[0049] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present application. Also, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0051] Figure 1 The basic process flow of the filtering positioning method for single-frequency users of the Beidou satellite-based augmentation system in an embodiment of the present application is schematically illustrated. DETAILED DESCRIPTION

[0052] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0053] The present application embodiment provides a filtering positioning method for a single-frequency user of a Beidou satellite-based augmentation system, such as Figure 1 As shown, the following steps are included:

[0054] In step S101, at the current time t k , get the current time t k Pseudorange observations of N GPS satellites and carrier phase observations Navigation message, BDSBAS single frequency enhanced message, and obtain the last time t k-1 Estimated value of user state variable and its covariance matrix in Yes k-1 The user's location and estimated clock error at the moment, Yes k-1 The estimated value of the first-order derivative of the user's position and clock error at the current moment; if the current moment is the initial epoch, then and The value of can be obtained by using the current time t k The pseudorange least squares positioning solution of .

[0055] In step S102, construct the current time t k In some embodiments, construct the current time t k The carrier phase smoothed pseudorange measurement includes:

[0056] The carrier phase smoothed pseudorange measurements are calculated as follows:

[0057]

[0058] In the formula, represents the current time t k Carrier phase smoothed pseudorange measurement of satellite i; represents the current time t k is the original pseudorange measurement of star i at the current moment; Indicates t k-1 The original pseudorange measurement of satellite i at time i; Yes k Carrier phase measurement of satellite i at time i; Yes k-1 The carrier phase measurement of satellite i at time λ is the wavelength of the signal corresponding to the frequency point, and τ is the smoothing time, for example, the value is 100.

[0059] In step S103, the current time t is calculated based on the constructed carrier phase smoothed pseudorange measurement. k The corrected orbit and clock parameters of GPS satellites.

[0060] In step S104, the current time t is calculated. k The tropospheric delay error and ionospheric delay error of the current time t k Correction of satellite pseudorange measurement errors;

[0061] In step S105, the current time t is estimated based on the Kalman filter. k The user's position parameters.

[0062] In estimating the current time t k After obtaining the user's position parameters, the user's position estimate can be output to perform subsequent epoch estimation, and then the filtering positioning of the single-frequency user can be repeatedly performed.

[0063] The method of the embodiment of the present application introduces a Kalman filter method into the BDSBAS B1C single-frequency enhanced positioning method to achieve the integration of the previous and next epochs of positioning information, which can effectively suppress high-frequency positioning errors and significantly improve the user positioning accuracy.

[0064] In some embodiments, the current time t is calculated based on the constructed carrier phase smoothed pseudorange measurement. k The corrected orbit and clock parameters of GPS satellites include:

[0065] Use the GPS L1C / A frequency navigation message to calculate the GPS satellite orbit clock error parameters. For the specific calculation method, refer to the requirements in the GPS signal space interface specification.

[0066] Parse the BDSBAS B1C single-frequency augmentation message to obtain the enhanced GPS satellite orbit / clock error correction number, and correct the satellite orbit and clock error. The parsing and use of the BDSBAS B1C single-frequency augmentation message can refer to the description of the BDSBAS single-frequency augmentation message in the relevant national standards. k The orbital clock error parameters corrected by the N GPS satellites that are enhanced at all times The first three items are the satellite i at t k The three-dimensional orbital position of satellite i at time t k The star clock error at the moment.

[0067] In some embodiments, the current time t is calculated k The tropospheric delay error of satellite i is calculated by using the tropospheric delay error model. The carrier phase smoothed pseudorange is corrected, and the tropospheric model calculation method refers to the relevant chapters of the RTCA DO-229E appendix.

[0068] In some embodiments, the current time t is calculated k The ionospheric delay error of satellite i is calculated by using the ionospheric model parameters broadcast in the navigation message. For specific calculation methods, please refer to the requirements in the GPS signal space interface specification.

[0069] In some embodiments, for the current time t k The satellite pseudorange measurement error correction includes:

[0070] The smoothed pseudorange measurement values ​​are corrected for tropospheric and ionospheric errors to meet the following requirements:

[0071]

[0072] in, Represents the error correction for the troposphere and ionosphere.

[0073] In some embodiments, the current time t is estimated based on Kalman filtering. k The user's location parameters include:

[0074] Predicting state variables:

[0075]

[0076] in, is the current time t k The predicted value of the user state variable, is the previous time t obtained in step S101 k-1 The estimated value of the user state variable, By t k-1 to k The state transfer matrix is ​​as follows:

[0077]

[0078] Prediction covariance:

[0079]

[0080] in, is the current time t k One-step prediction value of the user state variable covariance matrix, is the previous time t obtained in step S101 k-1 The covariance matrix of the estimated values ​​of the user state variables, is the noise variance matrix of the state transfer process, t is t k-1 to k time difference;

[0081] Calculate the filter gain matrix to satisfy:

[0082]

[0083] in, is the current time t k The Kalman filter gain matrix, is the design matrix of the measurement equation, is the measurement noise variance matrix of the measurement equation;

[0084] Defining the Design Matrix satisfy:

[0085]

[0086] in, is the unit direction vector from satellite i to user receiver R,

[0087]

[0088] The estimated state parameters satisfy:

[0089]

[0090] in, is the estimated current time t k The estimated value of the user state variable, is the current time t k The observation vector, the observation vector satisfy:

[0091]

[0092] In some embodiments, the user position estimate is output and the subsequent epoch estimation is performed. Specifically, the estimated user state variable estimate may be output. The first three items are the user’s current time t k The position result is output.

[0093] The method of this application proposes a filtering positioning method suitable for single-frequency users of the Beidou Satellite-Based Augmentation System, which improves the positioning accuracy of BDSABS B1C single-frequency users and expands the industry application of enhanced services. The method of this application introduces the Kalman filter positioning algorithm based on the use of B1C single-frequency enhanced message correction numbers to achieve the inheritance of the previous and next epochs of user positioning information, which can effectively filter the high-frequency components in the user positioning error, improve the user positioning accuracy, and meet the needs of more industry users.

[0094] An embodiment of the present application also proposes a filtering positioning system for single-frequency users of a Beidou satellite-based augmentation system, including a processor and a memory, wherein a computer program is stored in the memory, and when the computer program is executed by the processor, the steps of the filtering positioning method for single-frequency users of the Beidou satellite-based augmentation system as described above are implemented.

[0095] It should be noted that in the various embodiments of the present application, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "includes a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0096] The serial numbers of the above-mentioned embodiments of the present application are for description only and do not represent the advantages or disadvantages of the embodiments.

[0097] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present application, or the part that contributes to the prior art, can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, a magnetic disk, or an optical disk), and includes a number of instructions for a terminal (which can be a mobile phone, a computer, a server, an air conditioner, or a network device, etc.) to execute the methods described in each embodiment of the present application.

[0098] The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present application, ordinary technicians in this field can also make many forms without departing from the purpose of the present application and the scope of protection of the claims, all of which are within the protection of the present application.

Claims

1. A filtering positioning method for single-frequency users of Beidou satellite-based augmentation system, characterized in that: include: Get the current time t k The pseudo-range observation values ​​and carrier phase observation values ​​of N GPS satellites, navigation messages, BDSBAS single-frequency enhancement messages, and the last time t k-1 The estimated values ​​of the user state variables and their covariance matrix; Construct the current time t k Carrier phase smoothed pseudorange measurement; According to the constructed carrier phase smoothed pseudorange measurement, calculate the current time t k Corrected orbit and clock parameters of GPS satellites; and, Calculate the current time t k The tropospheric delay error and ionospheric delay error of the current time t k Correction of satellite pseudorange measurement errors; Estimate the current time t based on Kalman filtering k The user's position parameters.

2. The filtering positioning method for single-frequency users of the Beidou satellite-based augmentation system as claimed in claim 1, characterized in that: Construct the current time t k The carrier phase smoothed pseudorange measurement includes: The carrier phase smoothed pseudorange measurements are calculated as follows: In the formula, represents the current time t k Carrier phase smoothed pseudorange measurement of satellite i; represents the current time t k The raw pseudorange measurements of satellite i; Indicates t k-1 The original pseudorange measurement of satellite i at time i; Yes k Carrier phase measurement of satellite i at time i; Yes k-1 The carrier phase measurement of satellite i at time λ is the wavelength of the signal corresponding to the frequency point, and τ is the smoothing time.

3. The filtering positioning method for single-frequency users of the Beidou satellite-based augmentation system as claimed in claim 2, characterized in that: According to the constructed carrier phase smoothed pseudorange measurement, calculate the current time t k The corrected orbit and clock parameters of GPS satellites include: Use GPS L1C / A frequency navigation message to calculate GPS satellite orbit clock error parameters; The BDSBAS B1C single-frequency augmentation message is parsed to obtain the augmented GPS satellite orbit / clock error correction number, and the satellite orbit and clock error are corrected.

4. The filtering positioning method for single-frequency users of the Beidou satellite-based augmentation system as claimed in claim 2, characterized in that: Calculate the current time t k The tropospheric delay errors include: Using the tropospheric delay error model, calculate the tropospheric delay error of satellite i To correct the carrier phase smoothed pseudorange.

5. The filtering positioning method for single-frequency users of the Beidou satellite-based augmentation system as claimed in claim 4, characterized in that: Calculate the current time t k The ionospheric delay errors include: Calculate the ionospheric delay error of satellite i using the ionospheric model parameters broadcast in the navigation message 6. The filtering positioning method for single-frequency users of the Beidou satellite-based augmentation system as claimed in claim 5, characterized in that: For the current time t k The satellite pseudorange measurement error correction includes: The smoothed pseudorange measurement values ​​are corrected for tropospheric and ionospheric errors to meet the following requirements: in, Represents the error correction for the troposphere and ionosphere.

7. The filtering positioning method for single-frequency users of the Beidou satellite-based augmentation system as claimed in claim 6, characterized in that: Estimate the current time t based on Kalman filtering k The user's location parameters include: Predicting state variables: in, is the current time t k The predicted value of the user state variable, is the previous time t k-1 The estimated value of the user state variable, By t k-1 to k The state transfer matrix is ​​as follows: Prediction covariance: in, is the current time t k The predicted value of the user state variable covariance matrix, is the previous time t k-1 The covariance matrix of the estimated values ​​of the user state variables, is the noise variance matrix of the state transfer process, t is t k-1 to k time difference; Calculate the filter gain matrix to satisfy: in, is the current time t k The Kalman filter gain matrix, is the design matrix of the measurement equation, is the measurement noise variance matrix of the measurement equation; Defining the Design Matrix satisfy: in, is the unit direction vector from satellite i to user receiver R, The estimated state parameters satisfy: in, is the estimated current time t k The estimated value of the user state variable, is the current time t k The observation vector, the observation vector satisfy:

8. The filtering positioning method for single-frequency users of the Beidou satellite-based augmentation system as claimed in claim 1, characterized in that: Also includes: Outputs the user position estimate, performing post-epoch estimation.

9. A filtering positioning system for single-frequency users of the Beidou satellite-based augmentation system, characterized in that: It comprises a processor and a memory, wherein a computer program is stored in the memory, and when the computer program is executed by the processor, the steps of the filtering positioning method for single-frequency users of the Beidou satellite-based augmentation system as described in any one of claims 1 to 8 are implemented.

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