Early applications of civil GPS

Some civilian applications of GPS for land, sea, and air are discussed. Surveying, time transfer, and integrated navigation systems are some of the practical interim applications of the prototype satellites. Coverage charts showing the hours of visibility for GPS satellites at four widely separated locations around the globe are presented. The relative merits of different GPS user equipment architecture which affects dynamic performance, acquisition times, and ionospheric range errors, are considered. Three civil GPS user sets, developed for experimentation and interim applications, are described. Test results which assess the difference in accuracy between L1, C/A code only measurements and ionosphere corrected L1 and L2 p-code measurements are given. It is concluded that GPS using only the C/A code on L1 is better than most other positioning systems for users who can tolerate limited daily coverage.