Document Type : Research Paper

Author

• Abbas Ali Salehabadi

Member of Faculty, School of Surveying

Abstract

When in 1986, GPS satellites were launched into space, nobody could have predicted that this system should overtake traditional and classic methods in surveying activities (such as triangulation and traverse). Since then, almost two generations of GPS receivers have been produced. With advancements in human technology and knowledge regarding production of precise computers on smaller scales and with higher speeds of processing, new generations of GPS receivers have become smaller, lighter and of greater power and potential of implementation and storage of satellite measurements in comparison with old receivers. Considering these facts, the new generation of GPS receivers introduced into mark from the year 2000, offer vast hardware and software abilities with wonderful efficiency. These receivers, along with small size and lightness, have high power of initial processing in connection with preparation of positional information. These receivers are able to store information in the main memory up to 16 Mb. They can also receive all the information sent on L1 and L2 carrier frequencies. Therefore, it is possible through utilization of such receivers to achieve the same precision that old receivers obtained by observations as long as about thirty minutes. One of the innovations used in new generation of GPS receivers is a computer chip (IC) that has an astonishing power for removing effective systematic errors that affect GPS measurements, and therefore can provide new GPS receivers with the possibility of precise positioning. This computer chip, known as Paradigm Chip, acts like a small computer “brain” that controls all observational and calculative activities in the receiver.