(1)（
GPS) Global, all-weather continuous navigation and positioning capability. GPS can provide continuous and all-weather navigation and positioning capability for all kinds of users anywhere in the world or near earth space. Users do not need to transmit signals, so it can meet the needs of multiple users.
(2) (
GPS)Real time navigation, high positioning accuracy and short observation time. When using GPS positioning, position data can be obtained several times in 1 s. This near real-time navigation ability is of great significance to high dynamic users. At the same time, it can provide users with continuous three-dimensional position, three-dimensional velocity and accurate time information. At present, the real-time positioning accuracy using C / a code can reach 20-50m, the speed accuracy is 0.1m/s, the special processing can reach 0.005m/s, and the relative positioning accuracy can reach millimeter level.
With the continuous improvement of GPS system and the continuous updating of software, at present, the relative static positioning within 20km only takes 15-20min. During the rapid static relative positioning measurement, when the distance between each mobile station and the reference station is within 15km, the observation time of the mobile station only takes 1-2min, and then it can be positioned at any time. The observation of each station takes only a few seconds
