Abstract: A system and method for increasing jamming immunity in a GPS/INS system. The system includes a signal processor for receiving and down-converting GPS signals to a baseband frequency to provide I and Q (sine and cosine) signals. An integrate and dump operation is performed on the I and Q signals to provide GPS range and range rate residuals which are uncorrelated from sample to sample. A Kalman filter estimates navigation state corrections from the GPS range and range rate residuals. A NAV function, responsive to the output of the Kalman filter and range error and velocity error signals, provides guidance information and signals for correcting at least one of earth centered earth fixed (ECEF) position, velocity, initial attitude and IMU alignment states which are dynamically calculated from the range and range rate measurements.