Evaluation of Stability of GPS Satellite and Receiver Bias

An investigation is attempted to understand how the Differential Code Biases of the TrigNet receivers of the Global Position System vary over the South African region. The Differential Code Biases were determined for a one-year period for the prototype near-real Total Electron Content product currently being evaluated at the South African National Space Agency Space Weather Centre. The Differential Code Biases of the satellites that are provided by the Center for Orbit Determination in Europe were considered sufficiently stable to use the method of Ma and Murayama (2003) to determine the receiver Differential Code Biases. The annual performance shows that the daily variation in the receiver Differential Code Biases has a mean value of 3 Total Electron Contents Units. Based on the variations from multiple receivers it is inferred that the method results in a mean error of 3 Total Electron Content Units in the maps of Total Electron Content.