CN-121995420-A - Beidou PPP-B2B ambiguity fixing and improving method in complex mountain area environment

CN121995420ACN 121995420 ACN121995420 ACN 121995420ACN-121995420-A

Abstract

The invention discloses a Beidou PPP-B2B ambiguity fixing and improving method in a complex mountain area environment, which comprises the steps that a service end generates a precise ephemeris orbit based on broadcast ephemeris, an observation value and a space state representation broadcast by PPP-B2B, the uncalibrated phase delay of a satellite end is calculated according to the precise ephemeris orbit, the integer ambiguity is searched through integer least squares by utilizing the uncalibrated phase delay, a Laplace distribution parameter is estimated by combining regional ambiguity residual statistics, the Laplace distribution parameter is broadcast through NTRIP protocol, a client receives broadcast parameters and local data, the local precise ephemeris orbit is generated, and quick searching and fixing of the integer ambiguity are realized based on Bayesian integer estimation of the Laplace distribution, so that PPP fixing solution is obtained. The invention improves the fixing efficiency and the positioning accuracy of PPP ambiguity in complex mountain area environment.

Inventors

TANG JUN
Teng Hanyang
SUN YUE
DING MINGFEI

Assignees

昆明理工大学

Dates

Publication Date: 20260508
Application Date: 20260203

Claims (8)

1. The Beidou PPP-B2B ambiguity fixing and improving method in a complex mountain area environment is characterized by comprising the steps that the method is cooperatively executed by a server side and a client side, wherein: the process executed by the server side comprises the following steps: Receiving space state representation broadcasted by broadcast ephemeris, observation values and PPP-B2B signals, generating real-time precise ephemeris and orbits based on the space state representation and the broadcast ephemeris, obtaining satellite end uncalibrated phase delay based on the observation values and the real-time precise ephemeris and orbits, searching integer ambiguity by integer least square based on the satellite end uncalibrated phase delay, estimating Laplace distribution parameters according to statistical distribution of ambiguity residual errors in a region, broadcasting the satellite end uncalibrated phase delay and the Laplace distribution parameters by NTRIP protocol; The process executed by the client comprises the following steps: The method comprises the steps of receiving broadcast ephemeris, an observation value and space state representation and satellite end uncalibrated phase delay and Laplace distribution parameters broadcast by a server, generating local precise ephemeris and orbits based on the broadcast ephemeris and space state representation, searching and fixing integer ambiguity of the observation value by utilizing the satellite end uncalibrated phase delay and the Laplace distribution parameters through Bayesian integer estimation based on Laplace distribution, and calculating to obtain PPP fixed solutions based on the fixed integer ambiguity.
2. The method for improving the fixation of the Beidou PPP-B2B ambiguity in the complex mountain area environment of claim 1, wherein, The process of generating real-time precise ephemeris and orbit and local precise ephemeris and orbit comprises: Correcting the satellite orbit calculated by the broadcast ephemeris according to the satellite orbit correction in the space state representation to obtain a precise orbit, and correcting the satellite clock difference calculated by the broadcast ephemeris according to the satellite clock difference correction in the space state representation to obtain a precise clock difference.
3. The method for improving the fixation of the Beidou PPP-B2B ambiguity in the complex mountain area environment according to claim 2, wherein, The process of correcting the satellite orbit comprises the following steps: Performing IOD matching based on the reference time of the current time and the satellite orbit correction, calculating the orbit correction of the current time under a satellite fixed coordinate system by using the radial correction, the normal correction, the tangential correction and the speed correction provided in the space state representation, converting the orbit correction into a geocentric fixed coordinate system, and adding the converted correction and the satellite orbit calculated by the broadcast ephemeris to obtain a real-time precise orbit.
4. The method for improving the fixation of the Beidou PPP-B2B ambiguity in the complex mountain area environment according to claim 2, wherein, The process for correcting the satellite clock error comprises the following steps: Calculating the clock correction of the current moment relative to the reference moment based on the polynomial coefficient of the clock correction in the space state representation, and adding the calculated clock correction with the satellite clock calculated by the broadcast ephemeris to obtain the real-time precise clock.
5. The method for improving the fixation of the Beidou PPP-B2B ambiguity in the complex mountain area environment of claim 1, wherein, The process of calculating the satellite-side uncalibrated phase delay comprises the following steps: Based on the observed value, the real-time precise ephemeris and orbit, resolving the observed value by adopting a PPP static resolving model, and in the resolving process, resolving by fixing the known coordinates of at least one reference station to obtain floating ambiguity; the observation equation of the PPP static solution model is as follows: ; in the formula, Representing the values of the pseudorange observations, Representing the carrier phase observations of the carrier, Representing the geometric distance between the satellite and the receiver, Representing the speed of light in a vacuum, Representing the clock-difference of the receiver, Representing the clock rate of the satellite, Representing the tropospheric delay error (tcc) and, Representing the code pseudorange hardware delay between the receiver antenna and the signal, Representing the code pseudorange hardware delay between the satellite side signal transmitter to the satellite antenna, Representing the pseudorange measurement error, Representing the wavelength of the carrier wave, Representing the degree of ambiguity in the whole cycle, Representing the phase hardware delay of the receiver, Representing the phase hardware delay at the satellite side, Representing carrier phase measurement errors.
6. The method for improving the fixation of the Beidou PPP-B2B ambiguity in the complex mountain area environment of claim 1, wherein, The process of estimating the Laplace distribution parameter includes: The method comprises the steps of carrying out integer least square processing on observation data of a plurality of measuring stations in an area by utilizing the satellite end uncalibrated phase delay, searching to obtain integer ambiguity fixed solutions of the measuring stations corresponding to the satellites, calculating ambiguity residual errors between the integer ambiguity fixed solutions and the corresponding floating point solutions, counting all the ambiguity residual errors of all the measuring stations in the area, obtaining Laplace distribution parameters based on statistical distribution of the ambiguity residual errors, wherein the Laplace distribution parameters comprise position parameters and scale parameters, taking the median of all the ambiguity residual errors as the position parameters of the Laplace distribution, and calculating the scale parameters of the Laplace distribution by adopting a maximum likelihood estimation method.
7. The method for improving the fixation of the Beidou PPP-B2B ambiguity in the complex mountain area environment of claim 1, wherein, After the client generates the local precise ephemeris and orbit, performing cycle slip detection and rough error elimination on the observed value, and then searching and fixing integer ambiguity.
8. The method for improving the fixation of the Beidou PPP-B2B ambiguity in the complex mountain area environment of claim 1, wherein, The process of integer ambiguity searching through Bayesian integer estimation based on Laplace distribution comprises evaluating an integer candidate set centered on floating ambiguity based on scale parameters of the Laplace distribution, and selecting an optimal integer solution as a fixed integer ambiguity.

Description

Beidou PPP-B2B ambiguity fixing and improving method in complex mountain area environment Technical Field The invention belongs to the technical field of satellite positioning, and particularly relates to a Beidou PPP-B2B ambiguity fixing and improving method in a complex mountain area environment. Background In complex environments, the effect of GNSS positioning is subject to severe multipath effects and ionosphere, troposphere interference, and its positioning accuracy may degrade to decimeter level. Spatial state expressions (SSRs) are data formats used in RTCM protocols to convey orbit and clock correction of satellites, aimed at enhancing positioning accuracy, integrity, availability and continuity. The IGS analysis center and the commercial organizations monitor GNSS signals by using ground base stations, calculate errors and generate correction information, and broadcast the correction information to users by NTRIP protocol, thereby providing high-precision and high-reliability positioning service for the users. Satellite Based Augmentation Systems (SBAS) are a technology that improves Global Navigation Satellite System (GNSS) performance by satellite signals with the aim of enhancing positioning accuracy, integrity, availability and continuity. The SBAS monitors the GNSS signals with the ground base station, calculates the errors and generates correction information, which is then broadcast to the user via geostationary orbit satellites. The Beidou satellite navigation system (BDS) is served by PPP-B2B, and the Galileo satellite navigation system (GALILEO) is served by HAS, so that the satellite-based enhancement function is realized, and high-precision and high-reliability positioning service is provided for users. In order to solve the problems of serious multipath effect, low ambiguity fixing rate, frequent network signal interruption and the like in a complex mountain area environment, the invention provides a PPP ambiguity fixing method based on cascading ILS of Beidou PPP-B2B signals and BIE distributed by Laplace in the complex mountain area environment. Disclosure of Invention In order to solve the technical problems, the invention provides a Beidou PPP-B2B ambiguity fixing improvement method in a complex mountain area environment, so as to solve the problems in the prior art. In order to achieve the above purpose, the invention provides a Beidou PPP-B2B ambiguity fixing and improving method in a complex mountain area environment, which comprises the following steps: The method is cooperatively executed by a server and a client, wherein: the process executed by the server side comprises the following steps: Receiving space state representation broadcasted by broadcast ephemeris, observation values and PPP-B2B signals, generating real-time precise ephemeris and orbits based on the space state representation and the broadcast ephemeris, obtaining satellite end uncalibrated phase delay based on the observation values and the real-time precise ephemeris and orbits, searching integer ambiguity by integer least square based on the satellite end uncalibrated phase delay, estimating Laplace distribution parameters according to statistical distribution of ambiguity residual errors in a region, broadcasting the satellite end uncalibrated phase delay and the Laplace distribution parameters by NTRIP protocol; The process executed by the client comprises the following steps: The method comprises the steps of receiving broadcast ephemeris, an observation value and space state representation and satellite end uncalibrated phase delay and Laplace distribution parameters broadcast by a server, generating local precise ephemeris and orbits based on the broadcast ephemeris and space state representation, searching and fixing integer ambiguity of the observation value by utilizing the satellite end uncalibrated phase delay and the Laplace distribution parameters through Bayesian integer estimation based on Laplace distribution, and calculating to obtain PPP fixed solutions based on the fixed integer ambiguity. Optionally, the process of generating the real-time precise ephemeris and orbit and the local precise ephemeris and orbit includes: Correcting the satellite orbit calculated by the broadcast ephemeris according to the satellite orbit correction in the space state representation to obtain a precise orbit, and correcting the satellite clock difference calculated by the broadcast ephemeris according to the satellite clock difference correction in the space state representation to obtain a precise clock difference. Optionally, the process of correcting the satellite orbit includes: Performing IOD matching based on the reference time of the current time and the satellite orbit correction, calculating the orbit correction of the current time under a satellite fixed coordinate system by using the radial correction, the normal correction, the tangential correction and the speed correction provided in the space s