Validation of GPS receiver instrumental bias results for precise navigation

The positional accuracy of Global Positioning System (GPS) is affected by several errors, the most predominant error being the ionospheric delay. This delay is proportional to the total electron content (TEC). The dual frequency GPS observables can be used to estimate the TEC. The line-of-sight TEC estimated from dual frequency GPS data is corrupted by the instrumental biases of the GPS satellites and the receiver. The instrumental biases exist as the signals at the two GPS frequencies (f1=1575.42 MHz; f2=1227.60 MHz) experience different delays within the GPS satellite and receiver hardware. The estimation of the receiver instrumental bias plays a significant role in achieving required navigation accuracy for civil aviation applications. In this paper, receiver instrumental bias results due to a modified fitted receiver bias method, Kalman filter and singular value decomposition (SVD) algorithms are compared.