source:truck tracking webfleet solutions release time:2022-12-13 Hits: Popular:realtime gps tracker online
The basic principle of GPS navigation system is to measure the distance between the satellite with known position and the user's receiver, and then integrate the data of multiple satellites to know the specific position of the receiver.
To achieve this goal, the position of the satellite can be found in the satellite ephemeris according to the time recorded by the on-board clock. The distance from the user to the satellite is obtained by recording the time that the satellite signal propagates to the user, and then multiplying it by the speed of light (due to the interference of the atmospheric ionosphere, this distance is not the real distance between the user and the satellite, but the pseudo range (PR): when the GPS satellite is working normally, it will continuously transmit navigation messages with pseudo-random code (PN code for short) composed of 1 and 0 binary symbols.
There are two kinds of pseudo codes used in GPS system, namely C/A code for civilian use and P (Y) code for military use. The C/A code frequency is 1.023MHz, the repetition period is 1ms, and the code spacing is 1ms, which is equivalent to 300m; The P-code frequency is 10.23MHz, the repetition period is 266.4 days, and the code spacing is 0.1 microseconds, which is equivalent to 30m. Y code is formed on the basis of P code, which has better security performance. Navigation messages include satellite ephemeris, working conditions, clock correction, ionospheric delay correction, atmospheric refraction correction and other information. It is de modulated from satellite signal and transmitted on carrier frequency with 50b/s modulation. Each main frame of the navigation message contains 5 subframes, each of which is 6s long. 10 character codes for each of the first three frames; Repeat every 30 seconds and update every hour. The last two frames are 15000b in total. The content of navigation message mainly includes telemetry code, conversion code, the first, second and third data blocks, among which the most important is ephemeris data. When the user receives the navigation message, the distance between the satellite and the user can be obtained by extracting the satellite time and comparing it with his own clock. Then, the satellite ephemeris data in the navigation message can be used to calculate the position of the satellite when transmitting the message. The user's position and speed in the WGS-84 geodetic coordinate system can be known.
It can be seen that the role of the satellite part of the GPS navigation system is to continuously transmit navigation messages. However, since the clock used by the user receiver cannot always be synchronized with the satellite on-board clock, in addition to the user's three-dimensional coordinates x, y, z, a Δ T is the time difference between the satellite and the receiver as an unknown number, and then use four equations to solve the four unknowns. So if you want to know the position of the receiver, you must be able to receive at least four satellite signals.
Read recommendations:
GPS monitoring system develops rapidly.Hidden GPS Trackers Manufacturing
Last article:What are the components of GPS
Next article:Introduction to GPS application scope
Related Information
obd-II port gps tracker
2023-04-23Pet GPS Tracker manufacturer
2023-03-16GPS Tracking supplier
2023-04-11plug & play Obd gps tracker
2023-03-16gps vehicle tracking
2023-03-16Car gps tracking
2023-04-11fleet gps tracking supplier
2023-04-23gps vehicle tracker company
2023-04-11gps tracker no monthly fee
2023-03-16Dog gps tracker manufacturer
2023-04-23G08L - 4inch Smart Tail Light Tracker
2022-06-20YG119- Hunting Dog GPS tracker
2023-10-07NB20 -4G Bluetooth Smart Pet Tracker
2022-06-21TK08A Motorcycle GPS Tracker
2022-06-20TK103B
2022-06-20How to design an excellent personal GPS satellite locator
2023-02-21What is the application range of the car positioner?realtime gps tracker online manufacturer
2023-03-09Types of GPS
2022-07-26GPS data
2022-10-22What is GPS location time?
2022-10-26Advantages of Automotive Beidou/GPS Positioning Products.4G GPS Tracker for vehicles supplier
2023-09-15GPS is mainly composed of.obd-II port gps tracker Manufacturing
2023-05-20How accurate is GPS positioning?
2022-10-26GPS remote control function.realtime gps tracker online Production
2023-08-02gps vehicle tracker.GPS accuracy
2023-11-14What to do if the GPS positioning speed is slow.plug & play Obd gps tracker Solution
2023-04-08Preparation before using GPS
2022-12-28Types of GPS chips used by common GPS receivers
2022-12-30The role and functional characteristics of installing a GPS positioning system for taxis.gps vehicle
2023-10-07Principle of GPS indoor positioning technology
2022-11-25