A high-precision beidou time service method based on dual-frequency combination and pulse phase alignment

Abstract

The present application relates to the field of satellite high-precision time service, and particularly relates to a high-precision Beidou time service method based on double-frequency combination and pulse phase alignment, comprising: determining double-carrier frequency values, estimating the noise variance of each frequency pseudo-range in real time through signal-to-noise ratio mapping; determining the initial weight from the frequency and introducing a fine-tuning parameter to obtain the optimal fine-tuning parameter corresponding to the minimum combined pseudo-range noise variance and determine the optimized pseudo-range of each satellite. The theoretical value of the pseudo-range is obtained from the initial state vector of the receiver, a residual error and a weight diagonal matrix are constructed from the optimized pseudo-range, and the state vector is iteratively updated in combination with the observation matrix until the state correction vector meets the stopping condition. According to the final receiver clock error, the coarse propagation time delay is obtained, and in combination with the relative time delay variation of the pulse phase alignment, the final fused time delay is obtained as the time service reference. The present application improves the accuracy of high-precision Beidou time service.

Description

Technical Field

[0001] This invention relates to the field of satellite high-precision timing technology, and in particular to a high-precision BeiDou timing method based on dual-frequency combination and pulse phase alignment. Background Technology

[0002] With the full completion of the BeiDou Navigation Satellite System, high-precision time synchronization has important applications in critical infrastructure such as power dispatching, communication base stations, and financial transactions. Traditional BeiDou time synchronization methods mainly rely on single-frequency pseudorange observation or carrier phase measurement. However, in practical applications, satellite signals experience significant propagation delay errors when passing through the ionosphere. This error is inversely proportional to the square of the signal frequency, making it difficult for single-frequency receivers to effectively eliminate. Furthermore, during pseudocode correlation peak detection, the receiver's time delay estimation accuracy is limited by sampling rate constraints and multipath interference, making it difficult to achieve sub-nanosecond time synchronization requirements.

[0003] Existing BeiDou timing methods have two main problems: First, single-frequency timing cannot effectively eliminate the dynamic error of ionospheric delay, especially during periods of ionospheric activity or in high-latitude regions, where timing errors can reach tens of nanoseconds, making it difficult to meet the nanosecond-level timing requirements of high-precision application scenarios; Second, traditional pseudocode delay estimation methods are limited by sampling resolution and noise interference, resulting in insufficient pulse alignment accuracy, which prevents the full utilization of the advantages of carrier phase measurement and limits further improvement in timing accuracy. Summary of the Invention

[0004] This invention provides a high-precision BeiDou timing method based on dual-frequency combination and pulse phase alignment, which solves the problems of ionospheric delay error being difficult to eliminate and insufficient pulse alignment accuracy in existing BeiDou timing methods.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] This invention provides a high-precision BeiDou timing method based on dual-frequency combination and pulse phase alignment, comprising: Determine the values ​​of the dual carrier frequencies in the receiver; obtain the signal-to-noise ratio (SNR) corresponding to each carrier frequency; and estimate the pseudorange noise variance corresponding to each carrier frequency in real time through the SNR mapping. The initial weights of the two carrier frequencies are determined by the numerical values ​​of the two carrier frequencies. Fine-tuning parameters are introduced into the initial weights to obtain the fine-tuning weights of the two frequencies. The noise variance of the combined pseudorange is obtained by using the pseudorange noise variance corresponding to the two carrier frequencies and the fine-tuning weights of the two frequencies. The fine-tuning parameters that minimize the noise variance of the combined pseudorange are determined and denoted as the optimal fine-tuning parameters. The optimized pseudorange observation values ​​for each satellite are determined by using the optimal fine-tuning parameters. Obtain the receiver's initial state vector, which includes the receiver's initial three-dimensional spatial coordinates and initial receiver clock error; determine the pseudorange theoretical value using the state vector and compare it with the optimized pseudorange observation value to construct a residual vector and a weighted diagonal matrix; construct an observation matrix based on the geometric distances between all satellites and the receiver. The state correction vector is obtained by using the observation matrix, residual vector, and weight diagonal matrix; the state vector is updated by using the state correction vector to obtain the updated state vector; the iteration continues by using the updated state vector until the updated state correction vector meets the stopping iteration condition. Based on the receiver clock error and the speed of light in the final updated state correction vector, a rough propagation delay is obtained; By aligning the pulse phase, the relative delay change of each carrier frequency is obtained; by coarsely propagating the delay and the relative delay change, the final fusion delay is obtained and used as the final receiver clock bias for timing.

[0007] Furthermore, the pseudorange noise variance is specifically expressed by the formula:

[0008] In the formula, This represents the signal-to-noise ratio corresponding to each carrier frequency. This represents the pseudorange noise variance corresponding to each carrier frequency. This represents the proportionality constant.

[0009] Furthermore, obtaining the noise variance of the combined pseudorange includes: The initial weights of the two frequencies are as follows:

[0010]

[0011] The fine-tuning weights for the dual frequencies are as follows:

[0012]

[0013] The formula for the noise variance of the combined pseudorange is:

[0014] Will and Substituting into the noise variance formula for the combined pseudorange, we obtain the noise variance formula including the fine-tuning parameter, which is as follows:

[0015] In the formula, and For the receiver's two carrier frequencies, This represents the initial weight of the first carrier frequency. This represents the initial weight of the second carrier frequency. This indicates the fine-tuning weight for the first carrier frequency. This indicates the fine-tuning weight of the second carrier frequency. This represents the pseudorange noise variance corresponding to the first carrier frequency of the receiver. This represents the pseudorange noise variance corresponding to the second carrier frequency of the receiver. The noise variance represents the combined pseudorange. The formula for the noise variance including fine-tuning parameters. This indicates fine-tuning of parameters.

[0016] Furthermore, the optimized pseudorange observations for each satellite include:

[0017]

[0018]

[0019] In the formula, This represents the optimal fine-tuning weight for the first carrier frequency. This represents the optimal fine-tuning weight for the second carrier frequency. This represents the optimal fine-tuning parameters. This represents the pseudorange observation value at the first carrier frequency. This represents the pseudorange observation value of the second carrier frequency. This represents the optimized pseudorange observation value for each satellite.

[0020] Further, the state vector includes:

[0021] In the formula, The receiver's three-dimensional spatial coordinates, For receiver clock error, This is the transpose symbol for a vector. At the speed of light, This is due to clock skew.

[0022] Further, the residual vector and the weight diagonal matrix include: Based on the geometric distance between each satellite and the receiver and the receiver clock error, the theoretical pseudorange value of each satellite is obtained; based on the optimized pseudorange observation value and the theoretical pseudorange value of each satellite, the residual of each satellite is obtained; a residual vector is constructed using the residuals, and the weight of each satellite is determined; a weight diagonal matrix is ​​constructed using the weight of each satellite. The process for determining the weight of each satellite is as follows:

[0023] In the formula, Indicates the first The residual of each satellite For empirical threshold parameters, It is the absolute value symbol. Indicates the first The weight of each satellite.

[0024] Furthermore, the observation matrix includes:

[0025] In the formula, For the first The observation vector of each satellite, For the first The cosine value of the X-axis direction from the satellite to the receiver. For the first The cosine value of the Y-axis direction from the satellite to the receiver. For the first The cosine value of the Z-axis direction from the satellite to the receiver; The observation vectors of all satellites are combined into an observation matrix. ; In the formula, This is the observation vector for the first satellite.

[0026] Further, the state correction vector includes:

[0027] Solving for the state correction vector ; In the formula, This is a weighted diagonal matrix. This is the residual vector.

[0028] Furthermore, the stopping iteration condition includes: Less than a preset reference threshold or reaches the maximum preset number of iterations, where State correction vector The norm of .

[0029] Furthermore, the final fusion latency includes: The carrier signal is continuously tracked by a phase-locked loop, and the carrier phase measurement values ​​between adjacent epochs are recorded. and Then calculate the difference. The carrier phase change is obtained; based on the carrier phase change, the relative time delay change for each carrier frequency is obtained; the relative time delay change for each carrier frequency is specifically expressed by the formula:

[0030] in, This represents the carrier phase observation value at time t1. This represents the carrier phase observation value at time t2. This indicates the amount of carrier phase change. This represents the numerical value for each carrier frequency. This represents the relative time delay change for each carrier frequency. Pi; Calculate the average relative delay change between the two carrier frequencies; use the sum of the coarse propagation delay and the average relative delay change as the final fusion delay; use the final fusion delay as the final receiver clock bias for timing.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows: The numerical values ​​of the dual carrier frequencies in the receiver are determined; the signal-to-noise ratio (SNR) corresponding to each carrier frequency is obtained, and the pseudorange noise variance corresponding to each carrier frequency is estimated in real time through the SNR mapping; the pseudorange noise variance is mapped in real time through the SNR, enabling subsequent weight adjustments to adapt to changes in signal quality and improving optimization reliability; the initial weights of the dual frequencies are determined through the numerical values ​​of the dual carrier frequencies, and fine-tuning parameters are introduced into the initial weights to obtain the fine-tuning weights of the dual frequencies; the noise variance of the combined pseudorange is obtained through the pseudorange noise variance corresponding to the two carrier frequencies and the fine-tuning weights of the dual frequencies; and the method that minimizes the noise variance of the combined pseudorange is determined. The corresponding fine-tuning parameters are denoted as optimal fine-tuning parameters. The optimized pseudorange observation value for each satellite is determined using these optimal fine-tuning parameters. By introducing fine-tuning parameters and minimizing the combined noise variance, noise amplification caused by dual-frequency combination is effectively suppressed, improving single-satellite pseudorange accuracy. The initial state vector of the receiver is obtained, containing the receiver's initial three-dimensional spatial coordinates and initial receiver clock error. The theoretical pseudorange value is determined using the state vector, and its difference from the optimized pseudorange observation value is used to construct a residual vector and a weighted diagonal matrix. An observation matrix is ​​constructed based on the geometric distances between all satellites and the receiver. The residual and weighted diagonal matrix are constructed using the difference between the optimized and theoretical pseudorange values. A weighted matrix is ​​used to provide the foundation for robust iteration and enhance the ability to identify anomalies. A state correction vector is obtained through the observation matrix, residual vector, and weighted diagonal matrix. The state vector is updated using the state correction vector, and iteration continues until the updated state correction vector meets the stopping condition. Weighted least squares iteration is used to update the state vector, gradually eliminating gross errors and ensuring the robustness and stability of receiver position and clock error calculations. A coarse propagation delay is obtained based on the receiver clock error and speed of light in the final updated state correction vector. Finally, the receiver position and clock error are extracted from the converged state vector. The receiver clock error, combined with the speed of light, yields a coarse time delay, providing a reliable reference for subsequent high-precision fusion. Pulse phase alignment is used to obtain the relative time delay change for each carrier frequency. The final fusion time delay is obtained by combining the coarse propagation delay and the relative time delay change, serving as the final receiver clock error for timing. Pulse phase alignment technology is used to extract carrier phase changes, obtaining a high-resolution relative time delay to compensate for pseudorange noise. The coarse time delay is fused with the relative carrier phase change to achieve nanosecond-level timing accuracy, meeting the high-security, domestically produced timing requirements. This addresses the problems of ionospheric delay error elimination and insufficient pulse alignment accuracy in existing BeiDou timing methods. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This invention provides a flowchart illustrating the steps of a high-precision BeiDou timing method based on dual-frequency combination and pulse phase alignment. Detailed Implementation

[0034] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0035] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0036] To address the problems existing in the background technology, a high-precision BeiDou timing method based on dual-frequency combination and pulse phase alignment was designed, which has important practical significance.

[0037] like Figure 1 As shown, this invention provides a high-precision BeiDou timing method based on dual-frequency combination and pulse phase alignment, comprising the following steps: Step S1: Determine the values ​​of the dual carrier frequencies in the receiver; obtain the signal-to-noise ratio (SNR) corresponding to each carrier frequency, and estimate the pseudorange noise variance corresponding to each carrier frequency in real time through the SNR mapping; determine the initial weights of the dual frequencies through the values ​​of the dual carrier frequencies, introduce fine-tuning parameters into the initial weights to obtain the fine-tuning weights of the dual frequencies; obtain the noise variance of the combined pseudorange through the pseudorange noise variances corresponding to the two carrier frequencies and the fine-tuning weights of the dual frequencies; determine the fine-tuning parameters that minimize the noise variance of the combined pseudorange, and denot them as the optimal fine-tuning parameters; determine the optimized pseudorange observation values ​​for each satellite through the optimal fine-tuning parameters.

[0038] It should be noted that, in order to eliminate ionospheric delay while minimizing the measurement noise of the combined pseudorange, a dynamic weighted combination coefficient is introduced. This is because, although traditional dual-frequency combination can eliminate ionospheric delay, it amplifies the original noise of the two carrier frequencies (typically by about 2 to 3 times). The weights of the two carrier frequencies can be dynamically adjusted according to the real-time signal-to-noise ratio, minimizing the noise variance of the combined signal while satisfying the ionospheric elimination constraint. This improves the signal-to-noise ratio of the pseudorange of a single satellite and the final timing accuracy.

[0039] Specifically, the values ​​of the dual-carrier frequencies in the receiver are determined as follows: and The signal-to-noise ratio (SNR) for each carrier frequency is obtained, and the pseudorange noise variance for each carrier frequency is estimated in real time through SNR mapping; where two carrier frequencies correspond to the same receiver.

[0040] The pseudorange noise variance corresponding to each carrier frequency is specifically expressed by the following formula:

[0041] In the formula, This represents the signal-to-noise ratio corresponding to each carrier frequency. This represents the pseudorange noise variance corresponding to each carrier frequency. This represents a proportionality constant, which is an empirical value. In this embodiment, the proportionality constant is 50, but there is no specific limitation on the proportionality constant. The implementer can determine it according to the specific situation.

[0042] It should be noted that a higher SNR indicates a stronger signal, smaller measurement error, and lower pseudorange noise variance; conversely, a lower SNR indicates a weaker signal, larger measurement error, and higher pseudorange noise variance. These two are physically negatively correlated; therefore, the pseudorange noise variance can be determined by mapping the negative correlation between signal-to-noise ratio (SNR).

[0043] Step S11: Traditional fixed combination coefficient (only eliminating the ionosphere):

[0044]

[0045] This formula is obtained by solving the following two constraints simultaneously.

[0046] Dynamic weighting introduces fine-tuning parameters on this basis. ;

[0047]

[0048] Here, fine-tuning parameters are introduced. The purpose of adding one weight and subtracting another is to ensure that the sum of the two weights is 1.

[0049] Constraint 1: .

[0050] The derivation process is as follows: Because the ionospheric delay is inversely proportional to the square of the carrier frequency, and because the pseudorange of each carrier frequency can be expressed as: and In the formula, The geometric distance between the receiver and the satellite. For ionospheric related quantities, and For two carrier frequencies, and The pseudorange corresponding to the two carrier frequencies; The existing formula for the linear combination of dual-frequency pseudorange is:

[0051] Will and Substituting into the dual-frequency pseudorange combination formula, we get:

[0052]

[0053] To eliminate the ionosphere, we need to let Thus, terms containing A disappear.

[0054] In the formula, This is the pseudorange after the dual-frequency combination.

[0055] Constraint 2: .

[0056] Step S12: Optimal fine-tuning parameters Solve for; The formula for the noise variance of the combined pseudorange is:

[0057] Will and Substituting into the noise variance formula for the combined pseudorange, we obtain the noise variance formula including the fine-tuning parameter, which is as follows:

[0058] When the noise variance including the fine-tuning parameters is minimized, the weights of the two carrier frequencies are optimal; and because the fine-tuning parameters The coefficient of the quadratic term is greater than 0, therefore for By taking the derivative and setting it to zero, we can obtain the optimal fine-tuning parameters. The specific parameters of the optimal fine-tuning parameters are expressed by the following formula:

[0059] In the formula, and For the receiver's two carrier frequencies, This represents the initial weight of the first carrier frequency. This represents the initial weight of the second carrier frequency. This indicates the fine-tuning weight for the first carrier frequency. This indicates the fine-tuning weight of the second carrier frequency. This represents the pseudorange noise variance corresponding to the first carrier frequency of the receiver. This represents the pseudorange noise variance corresponding to the second carrier frequency of the receiver. The noise variance represents the combined pseudorange. The formula for the noise variance including fine-tuning parameters. This indicates fine-tuning of parameters.

[0060] Step S13: Calculate the optimized pseudorange for a single satellite;

[0061]

[0062]

[0063] In the formula, This represents the optimal fine-tuning weight for the first carrier frequency. This represents the optimal fine-tuning weight for the second carrier frequency. This represents the optimal fine-tuning parameters. This represents the pseudorange observation value at the first carrier frequency. This represents the pseudorange observation value of the second carrier frequency. This represents the optimized pseudorange observation value for each satellite.

[0064] At this point, optimized pseudorange observations for each satellite have been obtained, the first-order ionosphere has been eliminated, and the combined noise has been minimized.

[0065] Step S2: Obtain the receiver's initial state vector, which includes the receiver's initial three-dimensional spatial coordinates and initial receiver clock error; determine the pseudorange theoretical value using the state vector and compare it with the optimized pseudorange observation value to construct a residual vector and a weighted diagonal matrix; construct an observation matrix based on the geometric distances between all satellites and the receiver; obtain a state correction vector using the observation matrix, residual vector, and weighted diagonal matrix; update the state vector using the state correction vector to obtain the updated state vector; continue iterating using the updated state vector until the updated state correction vector meets the stopping iteration condition; obtain the coarse propagation delay based on the receiver clock error and speed of light in the final updated state correction vector.

[0066] It should be noted that, in order to suppress the impact of "bad satellites" severely affected by multipath interference or noise pollution on the final solution in pseudorange observations from multiple satellites, robust estimation is used. Even if step S1 optimizes the pseudorange data quality of each satellite, some satellites may still have large residual errors due to reflection, obstruction, or interference. Ordinary least squares treats all satellites equally, which means that even one bad satellite can skew the receiver clock error (timing result).

[0067] The goal of this step is to utilize all satellites. The receiver clock error was calculated. (Time synchronization result) and receiver location.

[0068] Specifically, the receiver's state vector is constructed; specifically represented as:

[0069] In the formula, The three-dimensional spatial coordinates of the receiver (the actual position to be estimated). For receiver clock error, At the speed of light, Due to clock skew, This is the transpose symbol for a vector.

[0070] Step S21: Construct the observation equations (for each satellite i); The observation equation is specifically expressed by the following formula:

[0071]

[0072] In the formula, For the first The three-dimensional spatial coordinates of the satellite For the first The geometric distance between the satellite and the receiver For the first The residuals of each satellite (i.e., pseudorange residuals).

[0073]

[0074] In the formula, For the first The observation vector of each satellite, For the first The cosine value of the X-axis direction from the satellite to the receiver. For the first The cosine value of the Y-axis direction from the satellite to the receiver. For the first The cosine value of the Z-axis direction from the satellite to the receiver. For receiver clock error The coefficient (the coefficient of the clock error term in the pseudorange observation is always 1).

[0075] Step S22: Robust iterative solution; Construct the error equation in least squares; specifically, it is expressed as:

[0076] in, , , .

[0077] In the formula, For the same receiver's state correction vector; This is the correction amount for receiver position and clock error. For the residual vector, This is the observation matrix for all satellites (composed of the observation vectors of all satellites). This is the observation vector for the first satellite. This is the residual of the first satellite.

[0078] The weight of each satellite is calculated using the Huber function based on the pseudorange residual of each satellite; the specific calculation formula is as follows:

[0079] Where k is an empirical threshold parameter, which is 1.5 to 3 times the residual standard deviation, usually k=2. For the first The weight of each satellite.

[0080] Construct a weighted diagonal matrix using the weights of all satellites; that is... Where n represents the number of satellites, This is a weighted diagonal matrix. This is the symbol for a diagonal matrix.

[0081] Based on the error equations in the weighted diagonal matrix and least squares, the error equation in weighted least squares is constructed, specifically expressed as:

[0082] Solve to obtain the updated state correction vector .

[0083] Then, it is determined whether the updated state correction vector satisfies the stopping iteration condition. If it does, the iteration stops; otherwise, the state vector is adjusted using the updated state correction vector. The updated state vector is obtained; the iteration continues using the updated state vector to obtain the state correction vector after the next iteration; the iteration stops when the stopping condition is met. Specifically, the updated state vector is obtained by correcting and adjusting the state vector using the updated state correction vector; this is expressed by the following formula:

[0084] In the formula, The updated state vector, This is the updated state correction vector.

[0085] The stopping iteration condition is: Less than a preset reference threshold (e.g., 0.01 meters) or reaching the maximum preset number of iterations (e.g., 5 times). Among these, State correction vector The norm (usually referring to the Euclidean norm, which is the square root of the sum of the squares of the components).

[0086] The final updated state correction vector is determined through the above iterations.

[0087] The coarse propagation delay is obtained based on the receiver clock error and the speed of light in the final updated state correction vector; the coarse propagation delay is calculated by dividing the receiver clock error in the final updated state correction vector by the speed of light. Here, the receiver clock error represents the distance.

[0088] Thus, a rough propagation delay is obtained.

[0089] Step S3: Obtain the relative delay change of each carrier frequency through pulse phase alignment; obtain the final fusion delay through coarse propagation delay and the relative delay change, and use it as the final receiver clock difference for timing.

[0090] It should be noted that, in order to simultaneously utilize the complementary characteristics of pseudorange, which can provide an absolute time reference but has high noise, and carrier phase, which has high accuracy but can only provide relative change, a weighted fusion or joint solution operation is performed: by using the absolute clock difference calculated by pseudorange as a reference, and then using high-precision carrier phase change to continuously and smoothly correct the reference, the integer ambiguity can be eliminated to obtain absolute time synchronization results, and the noise can be suppressed to a level far lower than that of pure pseudorange solution.

[0091] Specifically, the carrier signal is continuously tracked by a phase-locked loop, and the carrier phase measurement values ​​between adjacent epochs are recorded. and Then calculate the difference. The carrier phase change is obtained. Based on the carrier phase change, the relative time delay change for each carrier frequency is obtained; specifically, the relative time delay change for each carrier frequency is expressed by the formula:

[0092] in, This represents the carrier phase observation value at time t1. This represents the carrier phase observation value at time t2. This indicates the amount of carrier phase change. This represents the numerical value for each carrier frequency. This represents the relative time delay change for each carrier frequency. Pi is the mathematical constant of a circle.

[0093] Calculate the average relative delay change between the two carrier frequencies. The sum of the coarse propagation delay and the average relative delay change is used as the final fusion delay; this final fusion delay is then used as the final receiver clock bias for timing, thereby improving timing accuracy.

[0094] This concludes the embodiment.

[0095] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, optical storage, etc.) containing computer-usable program code.

[0096] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, systems, and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0097] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0098] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0099] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the present invention.

Claims

1. A high-precision BeiDou timing method based on dual-frequency combination and pulse phase alignment, characterized in that, include: Determine the values ​​of the dual carrier frequencies in the receiver; obtain the signal-to-noise ratio (SNR) corresponding to each carrier frequency; and estimate the pseudorange noise variance corresponding to each carrier frequency in real time through the SNR mapping. The initial weights of the two frequencies are determined by the numerical values ​​of the two carrier frequencies, and fine-tuning parameters are introduced into the initial weights to obtain the fine-tuning weights of the two frequencies. The noise variance of the combined pseudorange is obtained by using the pseudorange noise variance corresponding to the two carrier frequencies and the fine-tuning weights of the two frequencies. The fine-tuning parameters that minimize the noise variance of the combined pseudorange are determined and denoted as the optimal fine-tuning parameters. The optimized pseudorange observations for each satellite are then determined using the optimal fine-tuning parameters. Obtain the receiver's initial state vector, which includes the receiver's initial three-dimensional spatial coordinates and initial receiver clock error; determine the pseudorange theoretical value using the state vector and compare it with the optimized pseudorange observation value to construct a residual vector and a weighted diagonal matrix; construct an observation matrix based on the geometric distances between all satellites and the receiver. The state correction vector is obtained by using the observation matrix, residual vector, and weight diagonal matrix; the state vector is updated by using the state correction vector to obtain the updated state vector; the iteration continues by using the updated state vector until the updated state correction vector meets the stopping iteration condition. Based on the receiver clock error and the speed of light in the final updated state correction vector, a rough propagation delay is obtained; By aligning the pulse phase, the relative time delay change for each carrier frequency is obtained; The final fused delay is obtained by coarsely propagating the delay and the relative delay change, and is used as the final receiver clock bias for timing.

2. The high-precision BeiDou timing method based on dual-frequency combination and pulse phase alignment according to claim 1, characterized in that, The pseudorange noise variance is specifically expressed by the formula: In the formula, This represents the signal-to-noise ratio corresponding to each carrier frequency. This represents the pseudorange noise variance corresponding to each carrier frequency. This represents the proportionality constant.

3. The high-precision BeiDou timing method based on dual-frequency combination and pulse phase alignment according to claim 1, characterized in that, The acquisition of the noise variance of the combined pseudorange includes: The initial weights of the two frequencies are as follows: The fine-tuning weights for the dual frequencies are as follows: The formula for the noise variance of the combined pseudorange is: Will and Substituting into the noise variance formula for the combined pseudorange, we obtain the noise variance formula including the fine-tuning parameter, as follows: In the formula, and For the receiver's two carrier frequencies, This represents the initial weight of the first carrier frequency. This represents the initial weight of the second carrier frequency. This indicates the fine-tuning weight of the first carrier frequency. This indicates the fine-tuning weight of the second carrier frequency. This represents the pseudorange noise variance corresponding to the first carrier frequency of the receiver. This represents the pseudorange noise variance corresponding to the second carrier frequency of the receiver. The noise variance represents the combined pseudorange. The formula for the noise variance including fine-tuning parameters. This indicates fine-tuning of parameters.

4. The high-precision BeiDou timing method based on dual-frequency combination and pulse phase alignment according to claim 3, characterized in that, The optimized pseudorange observations for each satellite include: In the formula, This represents the optimal fine-tuning weight for the first carrier frequency. This represents the optimal fine-tuning weight for the second carrier frequency. This represents the optimal fine-tuning parameters. This represents the pseudorange observation value of the first carrier frequency. This represents the pseudorange observation value of the second carrier frequency. This represents the optimized pseudorange observation value for each satellite.

5. The high-precision BeiDou timing method based on dual-frequency combination and pulse phase alignment according to claim 1, characterized in that, The state vector includes: In the formula, The receiver's three-dimensional spatial coordinates, For receiver clock error, This is the transpose symbol for a vector. At the speed of light, This is due to clock skew.

6. A high-precision BeiDou timing method based on dual-frequency combination and pulse phase alignment according to claim 5, characterized in that, The residual vector and the weight diagonal matrix include: Based on the geometric distance between each satellite and the receiver and the receiver clock error, the theoretical pseudorange value of each satellite is obtained; based on the optimized pseudorange observation value and the theoretical pseudorange value of each satellite, the residual of each satellite is obtained; a residual vector is constructed using the residuals, and the weight of each satellite is determined; a weight diagonal matrix is ​​constructed using the weight of each satellite. The process for determining the weight of each satellite is as follows: In the formula, Indicates the first The residual of each satellite This is an empirical threshold parameter. It is the absolute value symbol. Indicates the first The weight of each satellite.

7. A high-precision BeiDou timing method based on dual-frequency combination and pulse phase alignment according to claim 6, characterized in that, The observation matrix includes: In the formula, For the first The observation vector of each satellite, For the first The cosine value of the X-axis direction from the satellite to the receiver. For the first The cosine value of the Y-axis direction from the satellite to the receiver. For the first The cosine value of the Z-axis direction from the satellite to the receiver; The observation vectors of all satellites are combined into an observation matrix. ; In the formula, This is the observation vector for the first satellite.

8. A high-precision BeiDou timing method based on dual-frequency combination and pulse phase alignment according to claim 7, characterized in that, The state correction vector includes: Solving for the state correction vector ; In the formula, This is a weighted diagonal matrix. This is the residual vector.

9. A high-precision BeiDou timing method based on dual-frequency combination and pulse phase alignment according to claim 8, characterized in that, The stopping iteration conditions include: Less than a preset reference threshold or reaches the maximum preset number of iterations, where State correction vector The style.

10. A high-precision BeiDou timing method based on dual-frequency combination and pulse phase alignment according to claim 1, characterized in that, The final fusion delay includes: The carrier signal is continuously tracked by a phase-locked loop, and the carrier phase measurement values ​​between adjacent epochs are recorded. and Then calculate the difference. The carrier phase change is obtained; based on the carrier phase change, the relative time delay change for each carrier frequency is obtained; the relative time delay change for each carrier frequency is specifically expressed by the formula: in, This represents the carrier phase observation value at time t1. This represents the carrier phase observation value at time t2. This indicates the amount of carrier phase change. This represents the numerical value for each carrier frequency. This represents the relative time delay change for each carrier frequency. Pi; Calculate the average relative delay change between the two carrier frequencies; use the sum of the coarse propagation delay and the average relative delay change as the final fusion delay; use the final fusion delay as the final receiver clock bias for timing.

Images