GPS technology and seismic monitoring earthquake

A, GPS satellite positioning 

GPS (Global Positioning System - GPS) is a U.S. Department of Defense primarily for military departments to meet the sea, land and air facilities for high-precision navigation and positioning requirements established. 1978, launched its first experimental satellite (Block Ⅰ), 1989 年 2 launch of the first month of working satellites (Block Ⅱ), to the end of 1994 all 24 satellites have been off, because life is about 5 years of satellite, the satellite currently in operation are 27, most later fired. 

1.GPS features

As the number of GPS satellites are more reasonable distribution of any place on Earth can be observed continuously synchronized to at least four satellites observed in our country up to 13 satellites simultaneously (currently running at about 27). In order to protect the global, all-weather continuous three-dimensional positioning. 

Real-time three-dimensional moving object to determine position and velocity, can protect the moving vehicle along the intended route of the run, but also can monitor and correct navigational routes, and select the best route. 

High positioning accuracy. Currently more than 1000km in the baseline, the relative positioning accuracy of up to 10-9; 100km up to 10-8. 

Stations do not need to pass between the visual, but also can shorten the observation time. 

Real-time location of the navigation technology is an important symbol of modernization to make GPS application areas continue to expand and become the largest scientific and technological achievements of the 20th century.

2.GPS the basic principles of positioning 

* Absolute positioning methods: absolute positioning, also known as single point positioning, is the center of mass relative to the earth coordinate system as the origin of coordinates in the coordinates of stations directly determined. The principle is based on GPS satellite to the user the dist