Self-calibrating large baseline interferometer for very precise emitter location using time difference of arrival and time difference of arrival rate

摘要

A passive system for locating a distant source of radio frequency energy, for example a pulsed radar transmitter, from a portable platform such as a moving aircraft. The disclosed system is non ambiguous in locating ability by way of using time difference of arrival and time difference of arrival-rate processing of signals received from the distant source. This is in contrast with phase-based locating wherein location ambiguities are inherent. The disclosed system is supported by an included recalibration subsystem enabling practical maintenance of time difference of arrival system algorithm accuracy notwithstanding physical component and signal delay changes attributable to thermal or other environment effects. Maintenance of delay measurements accurate into the tens of picosecond range by this recalibration arrangement are employed to obtain usefully precise energy source locations. Mathematical equation-based disclosures of signal delay algorithms and their recalibration are included.