source:truck tracking webfleet solutions release time:2022-12-28 Hits: Popular:realtime gps tracker online
????
????Generally, L1 carrier of GPS system is used for civil GPS, and the frequency is 1575.42 MHz. Two different pseudo-random noise codes, C/A code and P code, are loaded on this carrier frequency in a phase modulation manner. C/A code is a distance measurement code for civil use. The code length is 1023 symbols, i.e. 1023 times of jumping from digital zero to digital 1. The 1023 symbols repeat 1000 times per second, i.e. 1.023MHz, or once every millionth of a second. P code is a military code with a very long code length and a code speed of 10.23MHz, that is, it jumps once every millionth of a second.
????The GPS receiver calculates the time from satellite to receiver by comparing the symbol jitter, and then converts it into distance. Obviously, the time accuracy of P code is 10 times higher, and the distance accuracy is 10 times higher. The time accuracy of modern signal processing technology to calculate the symbol jitter is one percent of the code width. The distance converted from one millionth of a second is 300 meters, and its one percent is 3 meters. The precision of P code is one tenth of this value, namely 0.3m. In other words, when calculating the actual distance between a satellite and the receiver, the theoretical accuracy of C/A code is 3 meters.
????The receiver "knows" the distance between itself and the satellite, and cannot calculate its position, because it does not know the position of the satellite when transmitting radio waves. Therefore, a 50Hz navigation message is also loaded on the satellite carrier. This navigation message includes: satellite track parameters, clock parameters, orbit correction parameters, correction value of atmospheric refraction of GPS signals, etc. GPS receiver calculates the position of a satellite in space at a certain time through these parameters, then determines the distance between itself and the satellite, and then calculates its actual position. The navigation message has a total length of 1500 bits, and each cycle is 30 seconds in the case of 50Hz transmission.
????It may be boring, but this is one of the countless "why" hidden behind each GPS technical parameter. When you compare the technical parameters of various models of GPS receivers in GARMIN and MAGELLAN, you will find that the cold start time of all models of GPS receivers (that is, GPS knows nothing about the satellite and its location) is about 45 seconds. It is not that the manufacturer is lazy to improve the GPS performance, but it has reached the technical limit: 30 seconds out of 45 seconds are used to receive navigation messages, and the remaining 15 seconds are used to calculate the receiver position.
Read recommendations:
Last article锛?Actual demand and development trend of GPS market
Related Information
4G LTE gps tracker
2023-03-16Gps speed limiter manufacturer
2023-04-23fleet gps trackers company
2023-04-23Dog gps tracker manufacturer
2023-04-23trailer gps tracker custom
2023-04-23gps vehicle tracker distributors
2023-04-11fleet tracking mobile app
2023-03-16Magnetic gps tracker sales
2023-04-23GPS Tracker for vehicles Manufacturing
2023-03-164G GPS Tracker Production
2023-04-23GF30 Magnet GPS tracker with Voice listen
2022-06-21TK100 (GT06) Vehicle Tracker
2022-06-20GF20-Mini Magnet GPS Tracker
2022-06-21GF70L-Solar Magnetic Asset GPS Tracker
2023-10-07G200(L) -Magnet GPS Tracker
2022-06-20Disadvantages of Bluetooth GPS receiver.fleet tracking mobile app
2022-11-16How does GPS develop
2022-12-13What kind of gps tracker is easy to use?
2022-07-20The basic architecture and characteristics of GPS
2022-10-15A - GPS positioning
2022-10-25What is the difference between vehicle GPS positioning system and vehicle management system?GPS Trac
2023-03-28What are GPS satellite tracks?
2022-10-26GPS addressing locator
2023-07-27How to determine whether the car is equipped with a GPS positioner?trailer gps tracker Manufacturing
2023-03-17Global Positioning System Fix Data (GGA) GPS positioning information
2022-09-28GPS navigation system
2023-07-27GPS Personal Location
2022-11-01Vehicle Management System Based on Differential GPS Technology
2022-12-20The following aspects mainly affect the performance of GPS antenna
2022-11-12Principle of GPS system
2022-12-09