阅读说明：本技术 一种单频gps接收机的精密单点定位方法 (Precise single-point positioning method of single-frequency GPS receiver ) 是由 贺红斌 鲍笛 何佳玲 焦欢欢 于 2019-11-22 设计创作，主要内容包括：本发明公开了一种单频GPS接收机的精密单点定位方法,GPS数据计算与处理,完成单点定位处理；将GPS接收机的GPS数据和SBAS数据、无线通信模块的修正数据、外围串口的差分等数据进行综合处理和计算,在精确获取到卫星轨道和卫星的钟差值后,本发明涉及单频GPS接收机技术领域。该单频GPS接收机的精密单点定位方法,通过采用格网模型在大多数情况下只改正了电离层延迟的60％左右,剩余的40％左右的电离层延迟制约了精度的进一步提高,未探测出的周跳在很大程度上也会影响定位精度,采用多普勒法检测周跳,探测周跳的能力取决于多普勒观测值的精度和采样率,接收机的多普勒观测值精度好于2cm/s,采样率为15s时,能探测5周的周跳。(The invention discloses a precise single-point positioning method of a single-frequency GPS receiver, which comprises the steps of calculating and processing GPS data to finish single-point positioning processing; the invention relates to the technical field of single-frequency GPS receivers, which comprehensively processes and calculates GPS data and SBAS data of a GPS receiver, correction data of a wireless communication module, difference of peripheral serial ports and other data, and accurately obtains clock error values of a satellite orbit and a satellite. According to the precise single-point positioning method of the single-frequency GPS receiver, only about 60% of ionospheric delay is corrected by adopting a grid model under most conditions, the residual ionospheric delay of about 40% limits further improvement of precision, the positioning precision can be influenced to a great extent by undetected cycle slip, the cycle slip is detected by adopting a Doppler method, the cycle slip detection capability depends on the precision and the sampling rate of a Doppler observed value, the precision of the Doppler observed value of the receiver is better than 2cm/s, and when the sampling rate is 15s, the cycle slip of 5 weeks can be detected.)

1. A precise single-point positioning method of a single-frequency GPS receiver is characterized in that: the method specifically comprises the following steps:

s1, smoothing a pseudo range observation model by a carrier phase; in practical use, assuming that the ith satellite is observed, the pseudo-range observation equation and the carrier phase observation equation are respectively rho-CVm-CVig-Viu-Vime; phi lambda is rho-CVtR + CVtS + Viun-Vip-N lambda, wherein, rho is a pseudo-range observed value of the ith satellite, rho is a real geometric distance between the ith satellite and the receiver, C is the speed of light, Vm is a receiver clock error, Vig is the ith satellite clock error, Viu is an ionosphere delay, Vime is a troposphere delay, phi lambda is a carrier phase observed value of the ith satellite, lambda is the wavelength of a carrier, and N is the integer ambiguity, for two adjacent observation epochs (tk, tk-1), a phase-smoothed pseudorange model can be derived from two observation equations: p1(tk) ═ λ [ σ (tk) - ψ (tk-1) ] + ρ (tk-1) + V (tk-1) + Vip (tk-1) + C [ VtR (tk-1) -VtS (tk-1) ] ═ λ [ ψ (tk) - ψ (tk-1) ] + P1 (tk-1);

s2, calculating and processing GPS data to finish the single-point positioning processing; carrying out comprehensive processing and calculation on GPS data and SBAS data of a GPS receiver, correction data of a wireless communication module, difference of peripheral serial ports and other data to complete precise single-point positioning; after the clock error values of the satellite orbit and the satellite are accurately obtained, various error sources influencing the positioning result are considered and corrected by using a corresponding correction model; the precise ephemeris of the GPS satellite provided by the IGS station is combined to obtain the satellite orbit with high precision, and the clock error of the precise satellite is used for correcting the clock error; correcting the ionospheric error which has the maximum influence on the accuracy of single-frequency single-point positioning by adopting an ionospheric grid model; in the resolving process, the cycle slip is detected by utilizing the carrier phase change rate, the cycle slip is determined and repaired by utilizing a Chebyshev polynomial, the data preprocessing work such as pseudo-range phase smoothing is carried out by utilizing Hatch filtering, and the estimation calculation of the parameter to be solved is carried out by utilizing a Kalman filtering method;

s3, the single-frequency precise single-point positioning resolving process is data preprocessing, namely, firstly reading an observation file, an ionosphere file, a meteorological file, a precise orbit file and a clock error file, and preprocessing the data; then correcting relevant errors such as solid tide, ocean load, relativistic effect, antenna phase center deviation and the like to obtain clean data; secondly, residual errors are calculated, and overrun data are removed until all the residual errors meet the requirements; and finally, parameter estimation is carried out, coordinates of the measuring station and clock error of the receiver are calculated, static data are adopted to simulate dynamic data to be resolved or dynamic data are adopted to be resolved directly when experimental examples are resolved, and precise single-point positioning of the single-frequency GPS receiver is completed.

2. The precise single-point positioning method of a single-frequency GPS receiver according to claim 1, wherein: in step S1, the pseudorange observed value of a certain epoch is equal to the sum of the pseudorange observed value of the previous epoch and the difference between the carrier phase measurement values of the two epochs, and the pseudorange observed values and the carrier phase values of a plurality of epochs are used to obtain a plurality of pseudorange values of the same epoch, and the average value of the pseudorange observed values and the carrier phase values is the smoothed value of the pseudorange.

3. The precise single-point positioning method of a single-frequency GPS receiver according to claim 1, wherein: in step S1, because tropospheric errors, ionospheric errors, and relativistic errors can be corrected by the model, multipath errors are reduced by selecting a suitable observation location and using hardware resistant to multipath effects, and satellite clock errors are eliminated or reduced by using a precise clock error, it is not necessary to estimate the multipath errors as parameters, and therefore, the estimated parameters in the single-frequency precise single-point positioning include three-dimensional geocentric coordinates of the survey station and clock errors of the receiver.

4. The precise single-point positioning method of a single-frequency GPS receiver according to claim 1, wherein: in step S1, considering the influence of random noise of the observation value and other unmodeled system noise, and the single-point positioning cannot eliminate the influence of the observation value error in a differential manner, during data processing, the observation value variance-covariance is determined according to the quality factor of the observation value, and a satellite height angle weighting method is used.

5. The precise single-point positioning method of a single-frequency GPS receiver according to claim 1, wherein: in step S2, a grid correction model is selected for the ionospheric delay error, and the grid model is obtained by joint calculation with precision data processing software according to data of global IGS tracking stations after one week or more, and the result substantially reflects the change of the ionospheric delay error, and the grid model correction efficiency does not continuously decrease with time lapse, and the correction efficiency is stable and does not monotonically decrease with time lapse.

Technical Field

The invention relates to the technical field of single-frequency GPS receivers, in particular to a precise single-point positioning method of a single-frequency GPS receiver.

Background

The satellite positioning technology has been widely applied in navigation, measurement, timing, space technology and the like since the GPS was built in 1993, and becomes a third IT new growth point after communication and Internet, the positioning mode of the GPS is divided into two types of relative positioning and absolute positioning, the latter is also called single-point positioning, the GPS is put into use, the positioning mode of the relative positioning is developed rapidly, the positioning precision of the GPS is continuously improved from the first code relative positioning to the current RTK positioning, but the absolute positioning, namely the single-point positioning, is developed slowly, the traditional GPS single-point positioning is carried out by using code pseudo range, satellite orbit parameters and satellite clock correction provided by broadcast ephemeris, the satellite positioning method has the advantages that the data acquisition and processing are convenient, free and simple, a user can obtain three-dimensional coordinates in a WGS-84 coordinate system by using only one GPS receiver at any time, however, the accuracy of the pseudo-range observed value is generally from several decimeters to several meters, the error of the satellite position obtained by using the broadcast ephemeris can reach several meters to several tens of meters, and the error of the satellite clock difference is about ± 20ns, so the GPS single-point positioning receiver can only be generally used in the fields with low accuracy such as navigation, resource investigation and exploration.

The existing single-frequency precise single-point positioning has certain difficulties, in the establishment of a carrier phase smooth pseudo range observation model, ionosphere delay correction and cycle slip detection and repair, the static and dynamic positioning precision reaches the level of 0.5m in the plane direction and 1m in the elevation direction, on the premise of using a better receiver and carrying out data preprocessing, the static precision plane direction can even reach 0.2m, and the elevation direction can reach 0.5ml1, however, part of errors in the single-point positioning cannot be eliminated by adopting a difference solving mode, and various models and parameter estimation methods are required to be used for correction, and the cycle slip detection and the dynamic positioning of the single-frequency precise single-point positioning are difficult to operate.

Disclosure of Invention

Technical problem to be solved

Aiming at the defects of the prior art, the invention provides a precise single-point positioning method of a single-frequency GPS receiver, which solves the problems that part of errors in single-point positioning cannot be eliminated by adopting a difference solving mode, various models and parameter estimation methods are required to be used for correction, and the cycle slip detection and dynamic positioning of single-frequency precise single-point positioning are difficult to operate.

(II) technical scheme

In order to achieve the purpose, the invention is realized by the following technical scheme: a precise single-point positioning method of a single-frequency GPS receiver specifically comprises the following steps:

s1, smoothing a pseudo range observation model by a carrier phase; in practical use, assuming that the ith satellite is observed, the pseudo-range observation equation and the carrier phase observation equation are respectively rho-CVm-CVig-Viu-Vime; phi lambda is rho-CVtR + CVtS + Viun-Vip-N lambda, wherein, rho is a pseudo-range observed value of the ith satellite, rho is a real geometric distance between the ith satellite and the receiver, C is the speed of light, Vm is a receiver clock error, Vig is the ith satellite clock error, Viu is an ionosphere delay, Vime is a troposphere delay, phi lambda is a carrier phase observed value of the ith satellite, lambda is the wavelength of a carrier, and N is the integer ambiguity, for two adjacent observation epochs (tk, tk-1), a phase-smoothed pseudorange model can be derived from two observation equations: p1(tk) ═ λ [ σ (tk) - ψ (tk-1) ] + ρ (tk-1) + V (tk-1) + Vip (tk-1) + C [ VtR (tk-1) -VtS (tk-1) ] ═ λ [ ψ (tk) - ψ (tk-1) ] + P1 (tk-1);

s2, calculating and processing GPS data to finish the single-point positioning processing; carrying out comprehensive processing and calculation on GPS data and SBAS data of a GPS receiver, correction data of a wireless communication module, difference of peripheral serial ports and other data to complete precise single-point positioning; after the clock error values of the satellite orbit and the satellite are accurately obtained, various error sources influencing the positioning result are considered and corrected by using a corresponding correction model; the precise ephemeris of the GPS satellite provided by the IGS station is combined to obtain the satellite orbit with high precision, and the clock error of the precise satellite is used for correcting the clock error; correcting the ionospheric error which has the maximum influence on the accuracy of single-frequency single-point positioning by adopting an ionospheric grid model; in the resolving process, the cycle slip is detected by utilizing the carrier phase change rate, the cycle slip is determined and repaired by utilizing a Chebyshev polynomial, the data preprocessing work such as pseudo-range phase smoothing is carried out by utilizing Hatch filtering, and the estimation calculation of the parameter to be solved is carried out by utilizing a Kalman filtering method;

s3, the single-frequency precise single-point positioning resolving process is data preprocessing, namely, firstly reading an observation file, an ionosphere file, a meteorological file, a precise orbit file and a clock error file, and preprocessing the data; then correcting relevant errors such as solid tide, ocean load, relativistic effect, antenna phase center deviation and the like to obtain clean data; secondly, residual errors are calculated, and overrun data are removed until all the residual errors meet the requirements; and finally, parameter estimation is carried out, coordinates of the measuring station and clock error of the receiver are calculated, static data are adopted to simulate dynamic data to be resolved or dynamic data are adopted to be resolved directly when experimental examples are resolved, and precise single-point positioning of the single-frequency GPS receiver is completed.

Preferably, in step S1, the pseudorange observed value of one epoch is equal to the sum of the pseudorange observed value of the previous epoch and the difference between the carrier phase measurement values of the two epochs, a plurality of pseudorange values of the same epoch are obtained using the pseudorange observed values and the carrier phase values of a plurality of epochs, and the average value of the pseudorange observed values and the carrier phase values is a smoothed value of the pseudorange.

Preferably, in step S1, the tropospheric error, the ionospheric error, and the relativistic error may be corrected by a model, the multipath error is reduced by selecting a suitable observation location and using hardware for resisting multipath effect, and the satellite clock error is eliminated or reduced by using a precise clock error, so that it is not necessary to estimate the multipath error as a parameter, and therefore, the estimated parameters in the single-frequency precise single-point positioning include the three-dimensional geocentric coordinates of the station and the clock error of the receiver.

Preferably, in step S1, in consideration of the influence of random noise of the observation value and other unmodeled system noise, and the single-point positioning cannot eliminate the influence of the observation value error by using the differential method, during data processing, the observation value variance-covariance is determined according to the quality factor of the observation value, and a satellite height angle weighting method is adopted.

Preferably, in step S2, the ionospheric delay error is determined by using a grid correction model, where the grid model is obtained by jointly calculating, by using precision data processing software, data of global IGS tracking stations after one week or more, and the result substantially reflects the change of the ionospheric layer, the grid model correction efficiency does not continuously decrease with the lapse of time, the correction efficiency stability is good, and the correction efficiency does not monotonically decrease with the lapse of time.

(III) advantageous effects

The invention provides a precise single-point positioning method of a single-frequency GPS receiver. Compared with the prior art, the method has the following beneficial effects:

(1) the precise single-point positioning method of the single-frequency GPS receiver only corrects about 60% of ionospheric delay under most conditions by adopting the grid model, the residual ionospheric delay of about 40% limits further improvement of precision, undetected cycle slip also affects positioning precision to a great extent, the cycle slip is detected by adopting a Doppler method, the capability of detecting the cycle slip depends on the precision and sampling rate of a Doppler observed value, the precision of the Doppler observed value of the receiver is better than 2cm/s, and when the sampling rate is 15s, the cycle slip of 5 cycles can be detected.

(2) According to the precise single-point positioning method of the single-frequency GPS receiver, the carrier phase smoothing pseudo-range observation model is adopted to calculate data, and when single-frequency precise dynamic positioning is carried out, no matter a carrier is in a static state or in a dynamic state, no matter the mobility of a moving carrier is strong or weak, the precision of precise single-point positioning is greatly improved compared with the positioning precision of ordinary single-point positioning about 5 m.

(3) The precise single-point positioning method of the single-frequency GPS receiver weakens the multipath error by selecting a proper observation place and adopting hardware resisting multipath effect, and eliminates or weakens the satellite clock error by adopting the precise clock error, so the satellite clock error does not need to be estimated as a parameter, therefore, the estimated parameter in the single-frequency precise single-point positioning comprises the three-dimensional geocentric coordinate of a survey station and the clock error of the receiver, and the precise single-point positioning accuracy of the single-frequency GPS receiver can be effectively improved.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The embodiment of the invention provides a technical scheme that: a precise single-point positioning method of a single-frequency GPS receiver specifically comprises the following steps:

s1, smoothing a pseudo range observation model by a carrier phase; in practical use, assuming that the ith satellite is observed, the pseudo-range observation equation and the carrier phase observation equation are respectively rho-CVm-CVig-Viu-Vime; phi lambda is rho-CVtR + CVtS + Viun-Vip-N lambda, wherein, rho is a pseudo-range observed value of the ith satellite, rho is a real geometric distance between the ith satellite and the receiver, C is the speed of light, Vm is a receiver clock error, Vig is the ith satellite clock error, Viu is an ionosphere delay, Vime is a troposphere delay, phi lambda is a carrier phase observed value of the ith satellite, lambda is the wavelength of a carrier, and N is the integer ambiguity, for two adjacent observation epochs (tk, tk-1), a phase-smoothed pseudorange model can be derived from two observation equations: p1(tk) ═ λ [ σ (tk) - ψ (tk-1) ] + ρ (tk-1) + V (tk-1) + Vip (tk-1) + C [ VtR (tk-1) -VtS (tk-1) ] ═ λ [ ψ (tk) - ψ (tk-1) ] + P1 (tk-1);

s2, calculating and processing GPS data to finish the single-point positioning processing; carrying out comprehensive processing and calculation on GPS data and SBAS data of a GPS receiver, correction data of a wireless communication module, difference of peripheral serial ports and other data to complete precise single-point positioning; after the clock error values of the satellite orbit and the satellite are accurately obtained, various error sources influencing the positioning result are considered and corrected by using a corresponding correction model; the precise ephemeris of the GPS satellite provided by the IGS station is combined to obtain the satellite orbit with high precision, and the clock error of the precise satellite is used for correcting the clock error; correcting the ionospheric error which has the maximum influence on the accuracy of single-frequency single-point positioning by adopting an ionospheric grid model; in the resolving process, the cycle slip is detected by utilizing the carrier phase change rate, the cycle slip is determined and repaired by utilizing a Chebyshev polynomial, the data preprocessing work such as pseudo-range phase smoothing is carried out by utilizing Hatch filtering, and the estimation calculation of the parameter to be solved is carried out by utilizing a Kalman filtering method;

s3, the single-frequency precise single-point positioning resolving process is data preprocessing, namely, firstly reading an observation file, an ionosphere file, a meteorological file, a precise orbit file and a clock error file, and preprocessing the data; then correcting relevant errors such as solid tide, ocean load, relativistic effect, antenna phase center deviation and the like to obtain clean data; secondly, residual errors are calculated, and overrun data are removed until all the residual errors meet the requirements; and finally, parameter estimation is carried out, coordinates of a measuring station and clock errors of the receiver are calculated, static data are adopted to simulate dynamic data to be calculated or dynamic data are adopted to directly calculate when experimental examples are calculated, so that precise single-point positioning of the single-frequency GPS receiver is completed, and meanwhile, the content which is not described in detail in the specification belongs to the prior art which is known by technicians in the field.

In the present invention, in step S1, the pseudorange observed value of a certain epoch is equal to the sum of the pseudorange observed value of the previous epoch and the difference between the carrier phase measurement values of the two epochs, and the pseudorange observed values and the carrier phase values of a plurality of epochs are used to obtain a plurality of pseudorange values of the same epoch, and the average value of the pseudorange observed values and the carrier phase values is the smoothed value of the pseudorange.

In the invention, in step S1, because troposphere errors, ionosphere errors and relativistic errors can be corrected by a model, multipath errors are reduced by selecting a proper observation location and adopting hardware resistant to multipath effect, and satellite clock errors are eliminated or reduced by adopting precise clock errors, the multipath errors do not need to be taken as parameters for estimation, and therefore, the estimated parameters in single-frequency precise single-point positioning include three-dimensional geocentric coordinates of a station and clock errors of a receiver.

In the invention, in step S1, considering the influence of random noise of the observation value and other unmodeled system noise, and the single-point positioning cannot eliminate the influence of the error of the observation value by using a differential method, therefore, during data processing, the observation value variance-covariance is determined according to the quality factor of the observation value, and a satellite height angle weighting method is adopted.

In the invention, in step S2, a grid correction model is selected for ionospheric delay errors, the grid model is obtained by joint calculation through precision data processing software according to data of global IGS tracking stations after one week or even longer, the result basically reflects the change condition of the ionospheric layer, the grid model correction efficiency does not continuously decrease with the time lapse, the correction efficiency stability is good, and the correction efficiency does not monotonically decrease with the time lapse.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.