GPS (Global Position System, Global Positioning System) is called NAVSTAR GPS (NAV Navigation Satellite Timing And Ranging Global Position System). GPS is a space-based all-weather navigation system developed by the U.S. Department of Defense. It is used to meet military requirements for acquiring position, velocity, and time information in a common frame of reference on the ground or near ground.
DGPS (Differential Global Positioning System) installs a GPS monitoring receiver at a precise known location (base station) and calculates the distance corrections of the base station and the GPS satellites.
SBAS—(Satellite-Based Augmentation System) satellite-enhanced signal transponders equipped with geostationary orbit (GEO) satellites can broadcast ephemeris errors, satellite clock errors, and ionospheric delay corrections to users. Information, to achieve the improvement of the positioning accuracy of the original satellite navigation system, which has become a means for all aerospace major countries to compete for development. (Including WAAS, SDCM, EGNOS, MSAS, and GAGAN)
The AGPS (Assisted Global Positioning System) is a GPS operation mode. It can use the information of the base station of the mobile phone and cooperate with the traditional GPS satellites to make positioning faster.
C/A code—A pseudo-random code issued by a GPS satellite for rough ranging and capturing of GPS satellites. It is actually a kind of Gold code, which is generated by two G-codes consisting of 10-level feedback shift registers. Accuracy is within 14 meters.
P code—a pseudo-random code issued by a GPS satellite, which is a precision code corresponding to a C/A code, and has a code rate of 10.23 MHz. It is derived from the product of 2 pseudo-random codes PN1(t) and PN2(t). Can be controlled within 3 meters, but only for the military.