High-precision satellite navigation positioning solution based on Doppler frequency assisted smoothing

Abstract

The present invention discloses a high-precision satellite navigation and positioning solution method based on Doppler frequency-assisted smoothing. First, an optimal pseudorange filter and an optimal Doppler filter are constructed. Second, a coefficient filter is constructed. Third, the pseudorange observation ρ i [k] of the i-th satellite provided by the code loop in the navigation receiver at time k and the pseudodoppler observation γ i [k] are respectively input into the two filters in the first step for optimal smoothing filtering, and then the obtained results are input into the coefficient filter in the second step to obtain the smoothed pseudorange observation of the i-th satellite at time k. Fourth, the least squares solution technology is used to solve the smoothed pseudorange observation to obtain the three-dimensional position coordinates of the navigation receiver. The present invention can effectively utilize the Doppler observation, thereby improving the satellite navigation and positioning accuracy.

Description

Technical Field

[0001] The invention belongs to the technical field of satellite navigation and positioning, and in particular relates to a high-precision satellite navigation and positioning solution method based on Doppler frequency auxiliary smoothing. Background Art

[0002] In the field of satellite navigation and positioning, the navigation receiver can solve its three-dimensional position using the pseudo-range information and ephemeris information output by the tracking loop. How to use the measurement data provided by the tracking loop to achieve high-precision navigation receiver position solution has always been one of the hot topics in the field.

[0003] Most of the current positioning solutions for the position of navigation receivers are based on the least square solution method of pseudorange observations. In most navigation receivers, the error standard deviation of the pseudorange observation output by the pseudocode tracking loop is larger than the carrier observation output by the frequency-locked loop and the phase-locked loop. Therefore, the positioning accuracy of this least square solution method based solely on pseudorange observations is poor. In order to improve the positioning accuracy, Hatch proposed a method of smoothing pseudorange observations using carrier phase observations. Since the observation accuracy of carrier phase observations is high, this method can reduce the error standard deviation of pseudorange observations, thereby improving positioning accuracy. However, due to the fragility of the phase-locked loop in the tracking loop of the navigation receiver, in complex channel environments such as multipath fading, the phase-locked loop will frequently lose lock and cannot provide carrier phase observations, which makes the carrier phase smoothing pseudorange method ineffective. Compared with the phase-locked loop, the frequency-locked loop in the navigation receiver is often not easy to lose lock, so the Doppler frequency observation output by the frequency-locked loop can be used to improve the positioning accuracy. Zebo Zhou et al. proposed an algorithm for assisting positioning using Doppler frequency observations, but the algorithm requires prior information about the ratio of the standard deviation of the pseudorange observation error to the standard deviation of the Doppler frequency observation error, and the algorithm has the problem of mean deviation in positioning results as the number of points increases.

[0004] In summary, in the absence of prior information and with high robustness requirements, the existing satellite navigation positioning solution methods cannot effectively utilize Doppler frequency observations to provide high-precision positioning results. Summary of the invention

[0005] In view of this, the present invention provides a high-precision satellite navigation positioning solution method based on Doppler frequency assisted smoothing, which can achieve effective utilization of Doppler observations, thereby improving satellite navigation positioning accuracy.

[0006] The technical solution for implementing the present invention is as follows:

[0007] The high-precision satellite navigation positioning solution method based on Doppler frequency assisted smoothing includes the following steps:

[0008] Step 1: construct an optimized pseudorange filter and an optimized Doppler filter;

[0009] Step 2: construct a coefficient filter;

[0010] Step 3: Substitute the pseudo-range observation ρ of the i-th satellite at time k provided by the code loop in the navigation receiver i [k] and the pseudo-Doppler observation γ provided by the frequency-locked loop i [k] is respectively input into the two filters in step 1 for optimal smoothing filtering, and then the obtained result is input into the coefficient filter in step 2 to obtain the smoothed pseudorange observation value of the i-th satellite at time k;

[0011] Step 4: Use the least squares solution technique to solve the smoothed pseudo-range observations to obtain the three-dimensional position coordinates of the navigation receiver.

[0012] Furthermore, the optimized pseudorange filter B ρ [k] is:

[0013]

[0014]

[0015] Among them, k is the discrete point number, L is a set integer greater than 1, and n is a natural number representing the spline order. is a continuous-time B-spline function, expressed as:

[0016]

[0017] Where t is a continuous time variable, LT0 is the sampling interval of the spline coefficient, u(t) is a unit step function, and j is an intermediate variable with a value of 0 to n+1.

[0018] Furthermore, the optimized Doppler filter B γ [k] is:

[0019]

[0020] Where k is the discrete point number, LT0 is the sampling interval of the spline coefficient, L is a set integer greater than 1; δ[k] is the unit impulse response sequence; * represents the convolution operator; and Discrete-time B-spline function Get; n is a natural number, representing the spline order; The expression is:

[0021]

[0022] in, is a continuous-time B-spline function, expressed as:

[0023]

[0024] Among them, t is a continuous time variable; u(t) is a unit step function, and j is an intermediate variable with a value of 0 to n+1.

[0025] Furthermore, the coefficient filter c F [k] is:

[0026]

[0027] in,{·} -1 Represents the inverse impulse response of a discrete-time digital system.

[0028] Furthermore, the smoothed pseudorange observation value ρ Bi [k] is:

[0029]

[0030] Where i is a positive integer in the range of [1,M], and M is the number of observable satellites.

[0031] Beneficial effects:

[0032] Compared with conventional technologies, the high-precision satellite navigation positioning solution method based on Doppler frequency assistance proposed in the present invention has the following advantages:

[0033] 1. High positioning accuracy. Based on the natural derivative relationship between Doppler frequency observation and pseudo-range observation, and based on the B-spline approximation theory, the pseudo-range observation is optimized and smoothed using the Doppler frequency observation with high accuracy, which effectively improves the positioning accuracy.

[0034] 2. No additional prior information is required and the robustness is strong. The proposed solution method only takes Doppler frequency observation and pseudorange observation as input, and no additional prior information is required. In addition, due to the use of Doppler frequency observation, the proposed solution method can achieve higher positioning accuracy than conventional carrier phase smoothing technology in complex environments such as multipath fading. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a flow chart of a high-precision satellite navigation positioning solution method based on Doppler frequency assistance. DETAILED DESCRIPTION

[0036] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0037] The present invention provides a high-precision satellite navigation positioning solution method based on Doppler frequency assisted smoothing. The process of the solution method is as follows: Figure 1 As shown, the following steps are included:

[0038] Step 1: Construct the optimized pseudorange filter B ρ [k] and the optimal Doppler filter B γ [k], the expression is:

[0039]

[0040]

[0041] Where k is the discrete point number. LT0 is the sampling interval of the spline coefficient y[k], and L is an integer greater than 1. δ[k] is the unit impulse response sequence. * represents the convolution operator. and Discrete-time B-spline function Get. n is a natural number, representing the spline order. The expression is:

[0042]

[0043] in, is a continuous-time B-spline function, expressed as:

[0044]

[0045] Where t is a continuous time variable, u(t) is a unit step function, and j is an intermediate variable with a value of 0 to n+1.

[0046] Step 2: Construct coefficient filter c F [k], the expression is:

[0047]

[0048] in,{·} -1 Represents the inverse impulse response of a discrete-time digital system.

[0049] Step 3: The pseudo-range observation ρ of the i-th satellite at time k provided by the code loop in the navigation receiver i [k], and the pseudo-Doppler observation γ provided by the frequency-locked loop i [k] performs optimal smoothing filtering to obtain the pseudo-range observation value ρ of the i-th satellite after smoothing at time k Bi [k];

[0050]

[0051] Where i is a positive integer in the range of [1,M], and M is the number of observable satellites, which is a positive integer greater than or equal to 1.

[0052] Step 4: Use the least squares solution technique to calculate the smoothed pseudo-range observation ρ Bi [k] Calculate and obtain the three-dimensional position coordinates (x, y, z) of the navigation receiver T .

[0053] Among them, the optimized pseudorange filter B ρ [k], Optimized Doppler filter B γ [k] and coefficient filter c F The construction process of [k] includes the following steps:

[0054] 1. Define the spline coefficient y[k] and construct the error function ε, which is expressed as

[0055]

[0056] Its physical meaning is the sum of the squares of the pseudorange smoothing error and the pseudoDoppler smoothing error, where T0 is 1 / L of the spline coefficient sampling interval.

[0057] 2. Taking the derivative of ε with respect to the spline coefficient y[k] and setting the derivative equal to zero, we can obtain y[k], which is expressed as

[0058]

[0059] 3. The above formula can be regarded as the pseudo-range observation quantity ρ i The filtering result with [k] as input is compared with the pseudo-Doppler observation γ i [k] is the sum of the input filtering results. The above formula can be written as

[0060] y[k]=c F [k]*B ρ [k]*ρ i [k]+c F [k]*B γ [k]*γ i [k]

[0061] Among them B ρ [k], B γ [k] and c F The expression of [k] is the same as that in formulas (1), (2), and (5). This completes the optimization of the pseudorange filter B. ρ [k], Optimized Doppler filter B γ [k] and coefficient filter c F Construction of [k].

[0062] In summary, the above are only preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A high-precision satellite navigation positioning solution method based on Doppler frequency assisted smoothing, characterized in that: The following steps are involved: Step 1: construct an optimized pseudorange filter and an optimized Doppler filter; The optimized pseudorange filter B ρ [k] is: Among them, k is the discrete point number, L is a set integer greater than 1, and n is a natural number representing the spline order. is a continuous-time B-spline function, expressed as: Where t is a continuous time variable, LT0 is the sampling interval of the spline coefficient, u(t) is a unit step function, and j is an intermediate variable with a value of 0 to n+1; The optimized Doppler filter B γ [k] is: Where k is the discrete point number, LT0 is the sampling interval of the spline coefficient, L is an integer greater than 1; δ[k] is the unit impulse response sequence; * represents the convolution operator; and Discrete time B-spline function Get; n is a natural number, representing the spline order; The expression is: in, is a continuous-time B-spline function, expressed as: Where t is a continuous time variable; u(t) is a unit step function, and j is an intermediate variable with a value of 0 to n+1; Step 2: construct a coefficient filter; Step 3: The pseudo-range observation value ρ of the i-th satellite at time k provided by the code loop in the navigation receiver is i [k] and the pseudo-Doppler observation γ provided by the frequency-locked loop i [k] is respectively input into the two filters in step 1 for optimal smoothing filtering, and then the obtained result is input into the coefficient filter in step 2 to obtain the smoothed pseudorange observation value of the i-th satellite at time k; Step 4: Use the least squares solution technique to solve the smoothed pseudo-range observations to obtain the three-dimensional position coordinates of the navigation receiver.

2. The high-precision satellite navigation positioning solution method based on Doppler frequency assisted smoothing as claimed in claim 1, characterized in that: The coefficient filter c F [k] is: in,{·} -1 Represents the inverse impulse response of a discrete-time digital system.

3. The high-precision satellite navigation positioning solution method based on Doppler frequency assisted smoothing as claimed in claim 1, characterized in that: The smoothed pseudorange observation ρ Bi [k] is: Where i is a positive integer in the range of [1,M], and M is the number of observable satellites.

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