source:truck tracking webfleet solutions release time:2022-08-12 Hits: Popular:realtime gps tracker online
Due to the limitations of the Meridian satellite system, in 1973 the United States began to plan to develop a new navigation and positioning system, the GPS positioning system. After 20 years of hard work, the system was initially built and put into use in 1993. At this time, the system has a total of It consists of 24 satellites, including Block I experimental satellites and Block II, Block IIA working satellites. After the completion of the GPS navigation constellation, the use of C/A codes for navigation and positioning can also achieve high positioning accuracy. Therefore, considering the huge use of GPS in the military field, in order to prevent the enemy from using GPS to endanger the national security of the United States, the United States defense The Ministry stipulates that the SA technology should be implemented on all working satellites, that is, it is considered to reduce the accuracy of the navigation system. There are two specific technical means:
1. A technology that artificially adds errors to the broadcast ephemeris of the satellite to reduce the accuracy of the satellite ephemeris.
2. Technology, consciously adding a pseudo-random process rapid change to the satellite clock frequency.
On the other hand, in order to prevent the enemy from electronically spoofing and electronically jamming GPS satellite signals, the US Department of Defense has implemented the AS policy. The specific method is to add a strictly confidential W code to the GPS P code. After modulo two addition, a completely secret Y code is generated. Although the AS policy is a defensive measure, it also limits the possibility of unlicensed users to use the Y code, so it is impossible to obtain high-precision ranging codes, which greatly reduces the navigation accuracy.
Later, the GLONASS satellite navigation system managed by Russia announced that it would not implement the SA policy, so the positioning accuracy of its navigation system was much higher than that of the GPS system using the SA policy. Announced in 2009 to suspend the implementation of SA.
As satellite navigation systems play an increasingly important role in various fields of military and civilian use. However, the original GPS system has many shortcomings, such as: 1. It is difficult to receive satellite signals in hidden areas; 2. The energy of C/A code and P code is concentrated near the center frequency and is prone to human interference; 3. L2 carrier Ranging code is not modulated on the device, which makes it impossible for ordinary users to perform dual-frequency ionospheric delay correction, which affects positioning accuracy. Therefore, the C/A code was modulated on the L2 carrier of the navigation satellites of the subsequent Block IIR-M and Block IIF models, and later changed to the L2C code, so that civilian users can also use dual-frequency observation to improve positioning accuracy. Later, the L5 signal was added to the GPS navigation satellite after Block IIF, so that tri-frequency positioning can be used for non-military users.
Read recommendations:
Can the car GPS locator be used indoors and underground parking lots?realtime gps tracker online Man
Last article:GPS positioning technology
Next article:Composition of GPS system
Related Information
plug & play Obd gps tracker
2023-03-16Best hidden gps trackers
2023-03-16OBD GPS Tracker sales
2023-03-16Pet GPS Tracker Factory
2023-03-16Car gps tracking Production
2023-04-23cantrack g05
2023-04-11simple gps tracking manufacturer
2023-04-23obd-II port gps tracker
2023-04-11portable gps tracker distributors
2023-03-16real-time gps tracking Factory
2023-04-23G07L 4G GPS Tracker
2022-09-06Mini Sized GPS Tracker PCBA
2022-06-17NB20 -4G Bluetooth Smart Pet Tracker
2022-06-21G200(L) -Magnet GPS Tracker
2022-06-20GF70L-Solar Magnetic Asset GPS Tracker
2023-10-07What are the components of GPS
2022-09-23Origin of GPS
2022-08-13GPS receiver introduction.gps tracker no monthly fee Solution
2023-05-11GPS Function Introduction
2022-11-02Whether GPS positioning is GPS navigation.obd-II port gps tracker manufacture
2023-05-09The manufacturer will share with you how to provide accurate data for the fuel consumption recorder.
2023-05-09Calibration method for Beidou/GPS fuel sensor of large trucks.gps vehicle tracker
2023-09-18Classification of Automotive GPS Navigation Systems
2023-07-27GPS Navigation receiver
2023-06-02Application examples of GPS technology in navigators.fleet gps tracking supplier
2023-07-24GPS Starry Structure and Solving Process
2023-02-10Vehicle GPS positioner startup status classification description.gps tracker für auto webfleet solut
2023-03-28What are the commonly used car GPS positioner?
2023-02-25Vehicle positioning system.gps tracker app manufacturer
2023-07-04GPS positioning principle
2022-10-14