SPREAD SPECTRUM RECEIVER WITH MULTI-PATH CANCELLATION

A terrestrial C/A code GPS receiver system digitally samples, filters and stores a segment of 11 half chips of the received composite as a binary number and multiplexes this number for parallel correlation with each of a series of multibit code replicas for the satellites to be tracked. Multipath interference is canceled by deriving code phase timing from a model of the signal being tracked in each satellite channel. The model includes weighted, time delayed components of a plurality of time shifted versions of the code. A feedback control loop is used to match the amplitude profile of the model to the amplitude profile of the signal as received. The earliest version of the code having significant amplitude components may be used as the prompt code or the prompt code phase may be selected to be between the first and second versions of the code having significant amplitude components.