Abstract:

NAVSTAR-GPS has the widest usage and the largest number of users among the satellites for the purpose of determining location, recently. The basis of this system relies on the first satellite system for determining location, Navy Navigation Satellite System (TRANSIT). TRANSIT program, not satisfying the necessary expectations in years, is replaced by GPS Project in 1978. This new system, targeted at determination of spheric location, is built on 24 satellites and is controlled by land stations constructed in various regions in the world. GPS receivers reach the information of three dimensional location by interpreting radio signals sent through satellites. The measurement sensitivity of the receivers varies due to the type of receiver, athmosferic effect, the methods used for measurement and environmental influences. It can be said that GPS technology, widely used in geography researches, reflects faster and more sensible results compared to the classical methods of determining location