source:truck tracking webfleet solutions release time:2022-09-06 Hits: Popular:realtime gps tracker online
The main errors in GPS positioning are: star clock error, relativistic error, earth rotation error, ionosphere and troposphere error. 1) Star clock error The star clock error is formed by the error between the on-board clock and the GPS standard time. GPS measurement is based on precise time measurement. The star clock error time can reach 1ms, and the resulting distance deviation can reach 300Km. It must be be eliminated. The star clock error is generally represented by a binomial equation. (3) The purpose of correction is achieved by sending the binomial coefficients in the GPS ephemeris. After this correction, the error between the star clock and the GPS standard time can be controlled within 20ns. 2) Relativistic error According to the theory of relativity, after the clock with frequency on the ground is installed on the satellite running at the speed of , the clock frequency will change, and the amount of change is:
That is, the clock on the satellite is slower than that on the ground. To correct this error, the method of coefficient improvement can be used. This coefficient is broadcast in the GPS ephemeris to eliminate the relativistic error, and the relativistic error can be controlled within 70ns. 3) Earth rotation error GPS positioning adopts the agreement earth coordinate system that is fixed with the earth, and rotates around the z-axis together with the earth. The position (coordinate value) of the satellite relative to the protocol earth system is relative to the epoch. If the satellite is in a certain position in the protocol coordinate system at a certain moment of transmitting the signal, when the ground receiver receives the satellite signal, due to the rotation of the earth, the satellite is no longer at the position (coordinate value) at the moment of transmission. That is to say, in order to solve the position in the protocol coordinate system when the receiver receives the satellite signal, the coordinate system at this time must be used as the reference coordinate system for solving. The time used to solve the satellite position is the time when the satellite transmits the signal. In this way, the satellite position solved at this moment must be transformed into the position in the reference coordinate system. Let the angular velocity of the earth's rotation be we, and the signal propagation delay from the instant of the transmitted signal to the instant of the received signal is △t, then the longitude of the ascending node is adjusted to be in this time process, then the three-dimensional coordinate is adjusted to be (4) The positioning error caused by the earth's rotation is in meters level, which must be considered to be eliminated during precise positioning. 4) Ionospheric and tropospheric errors The ionosphere refers to the atmosphere above the earth at a height between 50 and 1000 km above the ground. The gas molecules in the ionosphere are strongly ionized due to the radiation of various rays from celestial bodies such as the sun, forming a large number of free electrons and positive ions. The ionospheric error mainly consists of ionospheric refraction error and ionospheric delay error. The error caused by it can reach about 50 meters in the vertical direction and about 150 meters in the horizontal direction. At present, a strict mathematical model cannot be used to describe the magnitude and variation of electron density. Therefore, to eliminate ionospheric errors, use ionospheric correction models or dual-frequency observations to correct them. The troposphere refers to the bottom layer of the atmosphere within a range of about 40km from the ground, accounting for 99% of the entire atmospheric mass. Its atmosphere is denser and more complex than the ionosphere. The troposphere is in contact with the ground, and the radiant heat energy is obtained from the ground, and the temperature decreases with the increase of altitude. Tropospheric refraction includes two parts: one is the path delay caused by the slowing of the propagation speed of electromagnetic waves or the speed of light in the atmosphere, which accounts for the main part; the other is that when the GPS satellite signal passes through the troposphere, the propagation path is also bent, which makes the measurement The distance is biased. It can reach 2.5 meters in the vertical direction and 20 meters in the horizontal direction. Tropospheric errors are also corrected by empirical models. The ionospheric and tropospheric errors are eliminated in the GPS ephemeris by giving the ionospheric tropospheric model and model parameters. The experimental data show that the effectiveness of using the model to improve the ionospheric error is 75%, and the effectiveness of the tropospheric error is 95%.
Read recommendations:
C32 (9~90V E-bikes/Motorcycle/Car gps tracker)
What daily life can GPS vehicle positioning terminals be applied?
Last article:GPS Navigation Solver
Next article:Experience of using wireless gps tracker GM09C
Related Information
car gps tracker price
2023-04-114G GPS Tracker for vehicles wholesaler
2023-04-23pet gps tracker cat Factory
2023-03-16Gps speed limiter Factory
2023-04-234G GPS Tracker sales
2023-04-234G GPS Tracker manufacture
2023-04-23realtime gps tracker online
2023-04-11car gps tracker manufacture
2023-04-23GPS Tracker custom
2023-04-11gps vehicle tracker Manufacturing
2023-04-11GF30 Magnet GPS tracker with Voice listen
2022-06-21GF70L-Solar Magnetic Asset GPS Tracker
2023-10-074G Wired GPS Tracker PCBA
2022-06-17TK100B- Accurate Pro version GT06/TK100
2023-10-06G08L - 4inch Smart Tail Light Tracker
2022-06-20The main problems affecting the development of the GPS industry
2023-02-16The complete installation step of the wiring car GPS positioner
2023-03-28Introduce the different types of GPS positioner
2023-02-25Is GPS really powerful?
2023-02-14GPS application
2022-07-25The significance of GPS monitoring and scheduling system.realtime gps tracker online wholesaler
2023-08-07GPS Tracker Basic Features
2022-09-21GPS anti -theft electronic system
2023-02-08Solar GPS positioning tracker solve worries
2023-02-23The IGS technology of GPS.GPS Tracker for vehicles distributors
2023-08-14New solutions of intelligent GPS anti-theft electronic system for automobiles
2022-12-07Overview of the car navigation system.Magnetic gps tracker Manufacturing
2023-05-18A GPS satellite
2022-10-12The difference between cylindrical lithium battery and polymer soft packed lithium battery
2022-10-18GPS vehicle satellite positioning simulation system design
2023-02-06