阅读说明：本技术 一种支持中长距离伪距差分定位的方法 (Method for supporting medium-and-long-distance pseudo-range differential positioning ) 是由 徐学永 周叶 夏羽 徐波 吴波 王琛琛 惠孟堂 汤深权 蒋虎 施金金 王伟 李 于 2020-12-09 设计创作，主要内容包括：本发明公开了一种支持中长距离伪距差分定位的方法,在计算伪距差分改正数时,利用双频GNSS信号构建无电离层组合,以消除电离层延迟误差项,使伪距差分改正数的服务范围由50km扩大至200km,同时利用载波相位平滑伪距的方法,使用低噪声的载波相位观测值对无电离层组合伪距观测值进行平滑处理,降低了无电离层组合伪距观测值的观测噪声,可生成低噪声、高精度的差分改正数,有利于中长距离的伪距差分定位。(The invention discloses a method for supporting medium-and-long-distance pseudo-range differential positioning, which comprises the steps of constructing an ionosphere-free combination by using a dual-frequency GNSS signal when calculating a pseudo-range differential correction to eliminate an ionosphere delay error item, expanding the service range of the pseudo-range differential correction from 50km to 200km, smoothing the ionosphere-free combined pseudo-range observation value by using a carrier phase smoothing method, reducing the observation noise of the ionosphere-free combined pseudo-range observation value, generating a low-noise and high-precision differential correction, and facilitating medium-and-long-distance pseudo-range differential positioning.)

1. A method for supporting medium-and-long-range pseudo-range differential positioning is characterized by comprising the following steps:

step 1, erecting a double-frequency receiver on a reference point, wherein the double-frequency receiver is used for receiving a broadcast ephemeris, a double-frequency carrier phase and a double-frequency pseudo range;

step 2, calculating the three-dimensional position (X) of the satellite in the current epoch according to the satellite orbit parameters released by the broadcast ephemeris and by combining the three-dimensional coordinates of the reference station^S,Y^S,Z^S) And the clock error deltat of the satellite, and calculating the geometric distance between the satellite and the reference station

Step 3, obtaining a dual-frequency pseudo range observed value P according to the dual-frequency pseudo range₁And P₂Using dual-frequency pseudorange observations P₁And P₂Constructing an ionosphere-free combination equation and generating an ionosphere-free combination pseudo-range observed value P_IF；

Step 4, obtaining a dual-frequency carrier phase observed value according to the dual-frequency carrier phaseAndusing dual-frequency carrier phase observationsAndconstructing a non-ionosphere combination equation to generate a non-ionosphere combination carrierPhase observation value

Step 5, combining the observed values of the carrier phases by using the ionosphere-free layerCombining pseudorange observations P for ionosphere-free layers_IFPerforming phase smoothing to generate smoothed ionospheric-free pseudo-range observed value

Step 6, smoothing the non-ionospheric pseudo-range observed valueIncorporating geometric distance of satellite to reference stationGenerating ionosphere-free pseudorange differential correction Δ P_IF；

Step 7, correcting value delta P of non-ionized layer pseudo range_IFAnd broadcasting to provide medium and long distance low noise pseudo range differential service for users.

2. The method for supporting medium-and-long range pseudorange differential positioning according to claim 1, wherein in step 3, ionosphere-free combined pseudorange observations P_IFThe calculation formula is as follows:

in the formula (f)₁And f₂The signal frequencies are the double-frequency observed values of the GNSS satellite; p₁For a signal frequency f₁Pseudo-range observation of (1), P₂For a signal frequency f₂Of the pseudo-range observations.

3. The method of claim 1, wherein in step 4, ionosphere-free combined carrier-phase observations are madeThe calculation formula is as follows:

wherein c is the speed of light,for a signal frequency f₁Is detected by the carrier-phase observation of (c),for a signal frequency f₂Of the carrier phase observation, P_IFAndionosphere error terms have been eliminated, but ionosphere-free combining also increases the observation noise.

4. The method of claim 1, wherein in step 5, the smoothed ionospheric-free pseudorange observations are smoothedThe calculation formula is as follows:

in the formula (I), the compound is shown in the specification,andare respectively shown at t_iAnd t_i-1Non-ionospheric pseudo-range observed value P after time smoothing_IF(t_i) Is shown at t_iAn ionospheric-free pseudo-range observed value at a moment, i representing a smoothing number; delta phi_IF(t_i-1,t_i) Representing the change value of the observed value of the carrier without an ionized layer between epochs; ionosphere-free pseudo-range observed value P_IF(t_i) After carrier phase smoothing, the observation noise is reduced.

5. The method of claim 1, wherein in step 6, ionospheric-free pseudorange differential corrections are Δ P_IFThe calculation formula is as follows:

in the formula,. DELTA.P_IF(t_i) Is t_iAn ionospheric-free pseudorange correction value for a time; at' is the receiver clock difference.

Technical Field

The invention belongs to the satellite navigation positioning technology, and particularly relates to a method for supporting medium-long distance pseudo-range differential positioning.

Background

In satellite positioning, when performing single-point positioning using pseudo-range observation values, the real-time positioning accuracy is about 10 meters. The pseudo-range differential positioning technology is characterized in that one or more reference stations with known coordinates in a certain area are used for receiving the three-dimensional position of a satellite in real time, independently calculating the pseudo-range differential correction of the satellite, and then transmitting the pseudo-range differential correction to a rover station through data transmission chain broadcasting to perform pseudo-range differential positioning, so that the positioning accuracy of the rover station in a meter level or even a sub-meter level is realized. However, the conventional single-station pseudo range differential technology has short range, and the accuracy of positioning is rapidly reduced along with the increase of the range. Therefore, a technology supporting medium-long distance pseudo-range differential positioning is provided, so that the medium-long distance pseudo-range differential positioning technology can process a medium-long baseline of 50-200 km. In the calculation of pseudo-range differential correction, the non-ionosphere combination is utilized to eliminate an ionosphere delay error item by utilizing the dual-frequency GNSS signal composition, the service range of pseudo-range differential is expanded, meanwhile, the non-ionosphere pseudo-range observation value is subjected to smoothing treatment by adopting a low-noise inter-epoch carrier phase observation value, the observation noise of the non-ionosphere pseudo-range observation value is reduced, the low-noise and high-precision pseudo-range differential correction is generated, the original single-frequency differential data is replaced, the differential service range is expanded, and the effect that the original single-frequency transmission technology achieves dual-frequency positioning is achieved.

Disclosure of Invention

The invention aims to provide a method for supporting medium-and-long-distance pseudo range differential positioning, which solves the problem that the traditional pseudo range differential positioning method is seriously influenced by an ionized layer delay error when processing a medium-and-long baseline of 50 km-200 km.

The technical solution for realizing the purpose of the invention is a method for supporting medium-long distance pseudo-range differential positioning, which comprises the following steps:

step 1, erecting a double-frequency receiver on a reference point, wherein the double-frequency receiver is used for receiving a broadcast ephemeris, a double-frequency carrier phase and a double-frequency pseudo range;

step 2, calculating the three-dimensional position (X) of the satellite in the current epoch according to the satellite orbit parameters released by the broadcast ephemeris and by combining the three-dimensional coordinates of the reference station^S,Y^S,Z^S) And the clock error deltat of the satellite, and calculating the geometric distance between the satellite and the reference station

Step 3, obtaining a dual-frequency pseudo range observed value P according to the dual-frequency pseudo range₁And P₂Using dual-frequency pseudorange observations P₁And P₂Constructing an ionosphere-free combination equation and generating an ionosphere-free combination pseudo-range observed value P_IF；

Step 4, obtaining a dual-frequency carrier phase observed value according to the dual-frequency carrier phaseAndusing dual-frequency carrier phase observationsAndconstructing a non-ionosphere combination equation to generate an observed value of a non-ionosphere combination carrier phase

Step 5, combining the observed values of the carrier phases by using the ionosphere-free layerCombining pseudorange observations P for ionosphere-free layers_IFPerforming phase smoothing to generate smoothed ionospheric-free pseudo-range observed value

Step 6, smoothing the non-ionospheric pseudo-range observed valueIncorporating geometric distance of satellite to reference stationGenerating ionosphere-free pseudorange differential correction Δ P_IF；

Step 7, correcting value delta P of non-ionized layer pseudo range_IFAnd broadcasting to provide medium and long distance low noise pseudo range differential service for users.

Compared with the prior art, the invention has the remarkable advantages that:

(1) the pseudo-range difference correction calculated by the invention eliminates the influence of an ionized layer, and the service range is expanded from 50km to 200 km.

(2) The carrier phase smoothing is carried out on the pseudo-range observed value without the ionized layer, so that the observation noise is greatly reduced, and the broadcasted differential correction is more stable and reliable.

Drawings

Fig. 1 is a flowchart illustrating a method for supporting medium-and-long-range pseudorange differential positioning according to the present invention.

Detailed Description

The present invention is described in further detail below with reference to the attached drawing figures.

With reference to fig. 1, a method for supporting medium-and-long-range pseudorange differential positioning includes the following steps:

step 1, erecting a double-frequency receiver on a reference point, wherein the double-frequency receiver is used for receiving a broadcast ephemeris, a double-frequency carrier phase and a double-frequency pseudo range;

step 2, calculating the three-dimensional position (X) of the satellite in the current epoch according to the satellite orbit parameters released by the broadcast ephemeris and by combining the three-dimensional coordinates of the reference station^S,Y^S,Z^S) And the clock error deltat of the satellite, and calculating the geometric distance between the satellite and the reference station

Step 3, obtaining a dual-frequency pseudo range observed value P according to the dual-frequency pseudo range₁And P₂Using dual-frequency pseudorange observations P₁And P₂Constructing an ionosphere-free combination equation and generating an ionosphere-free combination pseudo-range observed value P_IFAs shown in equation (1).

In the formula (f)₁And f₂The signal frequencies are the double-frequency observed values of the GNSS satellite; p₁For a signal frequency f₁Pseudo-range observation of (1), P₂For a signal frequency f₂Of the pseudo-range observations.

Step 4, obtaining a dual-frequency carrier phase observed value according to the dual-frequency carrier phaseAndusing dual-frequency carrier phase observationsAndconstructing a non-ionosphere combination equation to generate an observed value phi of the non-ionosphere combination carrier phase_IFAs shown in equation (2).

Wherein c is the speed of light,for a signal frequency f₁Is detected by the carrier-phase observation of (c),for a signal frequency f₂A carrier phase observation of (a). P_IFAnd phi_IFIonosphere error terms have been eliminated, but ionosphere-free combining also increases the observation noise.

Step 5, utilizing the ionosphere-free combined carrier phase observed value phi_IFCombining pseudorange observations P for ionosphere-free layers_IFPerforming phase smoothing to generate smoothed ionospheric-free pseudo-range observed valueThe observation noise is reduced as shown in equation (3).

In the formula (I), the compound is shown in the specification,andare respectively shown at t_iAnd t_i-1Non-ionospheric pseudo-range observed value P after time smoothing_IF(t_i) Is shown at t_iAn ionospheric-free pseudo-range observed value at a moment, i representing a smoothing number; delta phi_IF(t_i-1,t_i) And representing the observed value change value without an ionosphere between epochs. Ionosphere-free pseudo-range observed value P_IF(t_i) After carrier phase smoothing, the observation noise is reduced.

Step 6, smoothing the non-ionospheric pseudo-range observed valueIncorporating geometric distance of satellite to reference stationGenerating ionosphere-free pseudorange correction Δ P_IFAs shown in formula (4).

In the formula (4), Δ P_IF(t_i) Is t_iAn ionospheric-free pseudorange correction value for a time; at' is the receiver clock difference.

Step 7, correcting value delta P of non-ionized layer pseudo range_IFAnd broadcasting to meet medium and long distance low noise pseudo range differential service.

In summary, compared with the traditional pseudo-range single-point positioning method, the pseudo-range differential correction method provided by the invention uses the reference station user to provide high-precision pseudo-range differential correction numbers, and because the correction numbers use double-frequency deionization layer combination and smooth the pseudo-range by using the carrier phase observation value, the user positioning is not affected by hardware delay, troposphere delay, ionosphere delay and satellite orbit error, so that the pseudo-range differential positioning is more accurate and the precision can reach a sub-meter level. In addition, the medium-and-long distance pseudo range differential positioning supporting technology provided by the invention has the advantages that the operation mode is flexible, the data volume played by the reference station to the user is small, the influence of an ionosphere on the positioning precision under the medium-and-long distance condition is effectively inhibited, and the positioning precision and stability of the user are improved.