GPS is the current satellite positioning system, hailed as a milestone in human positioning technology. In summary, the system has the following characteristics:
(1) Global, continuous, and all-weather navigation and positioning capabilities. GPS provides continuous, all-weather navigation and positioning services to users in any location worldwide or in the near-space environment, without the need for signal transmission, thereby accommodating multiple users.
(2) Real-time navigation with high positioning accuracy and short observation time. When using GPS positioning, multiple position data can be obtained within 1 second, which is highly significant for high-dynamic users. It also provides continuous three-dimensional position, three-dimensional speed, and time information. Currently, real-time positioning accuracy using C/A code can reach 20-50 meters, with speed accuracy of 0.1 m/s, and can reach 0.005 m/s with special processing, achieving millimeter-level relative positioning accuracy.
With the continuous improvement of the GPS system and software updates, current relative static positioning within 20km requires only 15-20 minutes. During rapid static relative positioning measurements, when each roving station is within 15km of the base station, the observation time for the roving station is just 1-2 minutes. Afterward, positioning can be done at any time, with each station observation taking only a few seconds.

(3) No visibility required between stations: GPS surveying only requires an open sky above the station, without the need for visibility between stations. This saves a significant amount of marker-making costs (usually accounting for 30% to 50% of the total budget). As there is no requirement for visibility between points, the spacing of points can be adjusted as needed, making the site selection process highly flexible and eliminating the need for the measurement of transfer and transition points in traditional surveying.
(4) We offer a globally unified 3D geocentric coordinate system: GPS measurements can simultaneously determine the plane position and geodetic height of the station. Currently, GPS leveling meets the accuracy requirements of Level IV leveling. Additionally, GPS positioning is calculated within the globally unified WGS-84 coordinate system, ensuring that measurement results from different locations around the world are interrelated.
(5) Easy Instrument Operation: With continuous advancements in GPS receivers, the level of automation in GPS measurement has been increasing. During observations, the surveyor only needs to set up the instrument, connect the cables, measure the antenna height, and monitor the instrument's status. Other observation tasks, such as satellite acquisition, tracking, and recording, are all automatically completed by the instrument. Upon finishing the measurement, simply turn off the power, store the receiver, and the field data collection task is complete.
If long-duration continuous observations are required at a monitoring station, data can be transmitted to the data processing center via data communication, thereby achieving fully automated data collection and processing. Additionally, the receiver is becoming increasingly compact and lighter in weight, reducing the labor intensity for the measurement personnel and making fieldwork more comfortable.
(6) Strong anti-interference capability and good confidentiality: GPS utilizes spread spectrum technology and pseudo-random code technology, where users only need to receive the GPS signal; they do not emit any signal themselves, thereby avoiding interference from external signal sources.
(7) Versatile and Widely Applicable: GPS is a dual-use system for both military and civilian purposes, with a broad range of applications. Specific examples include: vehicle navigation and traffic management, patrol vehicle management, road construction, personal positioning, and navigation devices.