Robust GPS receiver for multipath immunity

A standard Global Positioning System (GPS) receiver is vulnerable to multipath signals. A standard receiver will exhibit bias in the timing estimate if multipath is present. This paper examines how a GPS receiver can be made immune to the presence of multipath by incorporating a bank of correlators in the code-tracking loop in place of the standard prompt gate, early-late gate scheme commonly in use. The presence of multipath distorts the response curve of the correlation gates, resulting in timing bias for the standard receiver. This bias can be estimated and removed by a bank of correlators occupying the timing error range defined by the early-late gate combination, resulting in a receiver that is robust in comparison with its standard counterpart. The acquisition performance of a standard GPS receiver and the proposed robust GPS receiver is compared to illustrate the improvement that can be obtained through the use of a correlation bank.