Abstract: A system and method for discriminating and mitigating spoofing signals incoming to a satellite navigation system. Beam steering techniques are used to steer a null toward a legitimate satellite signal that is being spoofed. The spoofing signal is then tracked and its angle of arrival measured. A null is steered toward the measured angle of arrival of the spoofing signal, and the spoofing signal is confirmed by determining if there is a signal remaining with nulls on both the legitimate satellite signal and the spoofing signal. The null toward the legitimate satellite signal is then replaced with unity gain.

Abstract: Two signals are correlated in a properly programmed digital computer to render a result reflecting the difference in time of arrival of the two signals at separate receiving stations from a common emitter station. Signals received at each of the receiver stations are converted into digital data and transmitted via a data link to a central correlation station. At the central correlation station, the individual digital signals are checked for magnitude and power content prior to conversion into the frequency domain by a fast Fourier transform. Previously stored calibration data from each of the receiver stations is combined with the frequency domain data to provide corrected information for correlation to determine the difference in time of arrival of signals from a common emitter station.

Abstract: Audio data is converted into a digital format at a selectable conversion rate and applied through a microprocessor into memory storage. Stored data is selectively recalled and reconverted into an analog format for reconstruction into human speech at a processing rate independent of the input storage rate. The write pointer address and the read pointer address during the storage and retrieval of data are maintained within a selected address differential in accordance with the input data rate and the processing rate. To repeat the retrieval of particular stored data from selected address locations, the data input storage is interrupted thereby holding in memory a selected portion of previously stored data. The amount of data retrieved during the repeat process is varied by controlling the write pointer and the differential address between the write pointer and the read pointer.