Nominal Signal Deformations : Limits on GPS Range Accuracy

Satellite-based navigation requires precise knowledge of the structure of the transmitted signals. For GPS, accurate knowledge of the shape of the ranging codes is required to ensure no biases are introduced into the position solution. It is generally presumed that all GPS-like satellite signals were virtually identical, however new research has shown that there may be significant variations between different GPS satellite signals. Since most GPS receivers require signals from four or more satellites, many GPS navigation solutions (past, present, and future) may contain unexplained bias errors ranging from a few centimeters to several meters.