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:
fleetmanagement webfleet solutions
GF30 Magnet GPS tracker with Voice listen
Why is it recommended to install the GPS vehicle positioning system?Portable car gps systems
The complete installation step of the wiring car GPS positioner
Last article:GPS positioning technology
Next article:Composition of GPS system
Related Information
airtag for dog
2023-03-16Dog gps tracker Vendor
2023-03-16real-time gps tracking custom
2023-04-23Cantrack GT06
2023-04-23GPS Tracking Manufacturing
2023-04-23Cantrack GPS Tracker
2023-03-16fleet gps tracking custom
2023-04-23Cantrack G05
2023-04-11fleet management software webfleet solutions
2023-03-16Hidden GPS Trackers supplier
2023-04-23G06L- 4G Car GPS Tracker
2022-09-06C32Plus (9~90V E-bikes/Motorcycle/Car gps tracker)
2022-06-2110000mAh Magnetic Asset GPS Tracker
2025-04-08VSL100 GPS Speed Limiter, Speed Governor
2022-06-193000mAh Magnet Asset GPS Tracker
2025-03-31The manufacturer introduced in detail what applications of GPS in aviation flight navigation.gps tra
2023-04-25GPS dynamic positioning
2022-08-20The GPS system consists of three parts
2022-12-06Advantages of Bluetooth GPS receiver.fleet tracking webfleet solutions
2022-11-16GPS positioner function.realtime gps tracker online wholesale
2023-04-07The characteristics and composition of the car GPS positioner.mileage tracking webfleet solutions
2023-03-08There are problems that occur on the four hardware of GPS.obd2 gps tracker verizon distributors
2023-04-14Can the GPS positioning system help the breeding industry save costs?
2023-02-22Car GPS Pharmaceutical Pharmacopoeia
2023-05-16Composition unit of on-board system
2022-12-09gps vehicle tracker.The role of installing GPS satellite positioning devices in the sales and leasin
2023-10-27Simulator test GPS
2022-10-10Fire truck installed with GPS global positioning navigation system
2023-02-06About GPS Drift
2022-08-19GPS forward direction (heading).gps tracker for bike wholesale
2023-06-10