Abstract
The global positioning system (GPS) is a satellite based navigation system which can give twenty-four hour three-dimensional worldwide coverage. The system consists of space, control, and user segments. The GPS receiver is part of the user segment. The function of this twelve channel GPS receiver is to acquire and track pseudorandom noise (PRN) ranging codes from twelve satellites simultaneously, to measure the pseudorange from each satellite, and to determines the user position, velocity, and time. The differential GPS (DGPS) technique is used to remove most pseudorange bias errors and the effects of selective availability. The twelve channel receiver of the DGPS reference station tracks all satellites in view and generates the pseudorange corrections and range rate corrections for other GPS users. It eliminates selective availability and other bias errors, and improves the positioning accuracy of the other standard positioning service users. This work presents the development of the data processing software for this twelve channel GPS receiver and a DGPS ground reference station. The software demodulates navigation message from each satellite having been tracked and computes the corrections to satellite clock bias and signal propagation delays in ionospheric and tropospheric media. The software uses the pseudoranges from all satellites having been tracked to determine the position of receiver by solving an overdetermined matrix. In this way, it eliminates the necessity to select the four satellites having good dilution of precision and provides the better position fix.
Ren, Juxiang (1995). Design of a twelve channel GPS receiver and a DGPS reference station - Data processing part. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1995 -THESIS -R46.