Usability of low-cost L1 frequency GPS receivers in surveying applications

Since the launch of the first Global Positioning System (GPS) satellite in 1978, the GPS has been used for a wide range of applications that require different accuracy levels as well as reliability or availability. It is widely used for civilian navigation and positioning, surveying and scientific applications. Different application and different accuracy requirements need to use different receiver classes. For instance a hand held GPS receivers of a few hundred US dollars can be used for the applications that require less accuracy whereas, carrier phase observations should be used for high-accuracy geodetic applications. The second one requires high quality and relatively expensive single or dual frequency GPS receivers. Such a single frequency receivers of about US$5,000 whereas dual frequency receiver typically costs more than about US$15,000 and at least two of them should be used simultaneously to perform baseline surveys. On the other hand, in recent years OEM type low-cost receivers/boards that can output carrier phase data have begun to be used as an alternative to the geodetic grades. The main objective of this research is to develop an accurate GPS-based positioning system employing the low cost L1 GPS OEM boards. In this study, Thales Navigation AC12 GPS OEM boards were selected as the low-cost GPS receiver. In the frame of this study, the possibility of using low-cost single frequency GPS receiver for high-accuracy positioning is investigated. A number of static and kinematic experiments were conducted in the Istanbul Technical University Ayazaga Campus, Turkey to assess the performance of the developed system as a function of occupation time (from 30 minutes to 3 hours), different baseline lengths (from approx. 0.2 km to over 50 km) and antenna configuration (single frequency geodetic antenna) configurations in differential mode. Collected data were processed by Bernese Scientific GPS Software Version 5.0 developed at the University of Bern as well as with a commercial software. The initial accuracy results of the static and kinematic test measurements show that the level of accuracy achieved by the presented system can be used for variety of surveying and GIS applications. Furthermore, using such as that OEM system could reduce the cost of the GPS receiver and would be decreased the cost of surveying task.