Patent ID: 6018312
Filing Date: 2000-01-25
Classification: G01S

Abstract:
A method of locating the source of an unknown signal received by a plurality of signal relays, the method including the steps of:(a) arranging for a plurality of receivers to receive the unknown signal from respective signal relays;(b) arranging for the receivers to receive respective reference signals from respective signal relays, the reference signals either being replicas of a single signal or being replicas of signals locked in frequency, time and phase to a single signal and the reference signals being transmitted to the signal relays from reference transmitting means of known location;(c) separating the respective unknown signal and reference signal received by each receiver from one another and processing them coherently to preserve their timing and phase information relative to each other;(d) performing cross ambiguity function processing of the processed reference signals and the processed unknown signals and employing the processed reference signals to counteract phase noise and frequency drift effects in the unknown signals in order to determine at least one of the following:(i) values of the Differential Time Offset (DTO) and Differential Frequency Offset (DFO) of the unknown signals;(ii) values of the DTO of the unknown signals corresponding to different signal relay positions,(iii) values of the DFO of the unknown signals corresponding to different signal relay positions,(iv) values of the DTO of the unknown signals corresponding to different combinations of signal relays,(v) values of the DFO of the unknown signals corresponding to different combinations of signal relays.