GPS L1 Carrier Phase Navigation Processing

Abstract

In early 2002, Queensland University of Technology (QUT) commenced to develop its own low-cost Global Positioning System (GPS) receiver with the capability for space applications such as satellites in Low Earth Orbits, and sounding rockets. This is named the SPace Applications Receiver (SPARx). This receiver development is based on the Zarlink (formerly known as Mitel) GP2000 Chip set and is a modification of the Mitel Orion 12 channel receiver design. Commercially available GPS receivers for space applications are few and expensive. The QUT SPARx based on the Mitel Orion GPS receiver design is cost effective for space applications. At QUT its use is being maximized for space applications and carrier phase processing in a cost-effective and specific way.

To build upon previous SPARx software developments made from 2002 to 2003, the receiver is required to be modified to have L1 carrier phase navigation capability. Such an improvement is necessary for the receiver to be used in 3-axis attitude determination and relative navigation using carrier phase.

The focus of this research is on the implementation of the L1 carrier phase measurement capability with SPARx. This is to enable the use of improved navigation algorithms. Specific emphasis is given to the areas of time synchronization, the carrier phase implementation and carrier phase differential GPS with SPARx. Test results conducted in the area of time synchronization and comparisons with other carrier phase capable GPS receivers are given, as well as an investigation of the use of SPARx in carrier phase differential GPS. Following these, conclusions and recommendations are given for further improvements to SPARx.