Moving emitter passive location from moving platform
AssigneeThe United States of America as represented by the Secretary of the Air Force
InventorThomas L. Madden
Life of this patent
Estimating the term…
Abstract
A moving platform to moving target relative locating apparatus using long baseline interferometer algorithm measurements and signal time difference of arrival data to operate the algorithm. Signal delays measuring in a few picoseconds are used in plural interferometer algorithms to determine straight-line vector paths between moving platform and moving target. Self-calibration of the picosecond time difference of arrival signal paths is provided. Use of the invention to passively locate a moving target in azimuth elevation and range from a moving aircraft using either aircraft-mounted or aircraft-tethered radio frequency signal antennas and a single pulse of received data is also included.
Claims18
Passive moving signal source relative-locating apparatus comprising the combination of:
- a time difference of arrival interferometer algorithm airborne signal locating system disposed within signal reception range of said moving signal source;
- multi-channel signal reception port apparatus disposed in physically segregated locations attending an aircraft carrying said airborne signal locating system;
- said multi-channel signal reception apparatus including first signal reception port apparatus disposed on a first physical portion of said aircraft and connected with a receiver apparatus within said aircraft by a first signal delay-calibrated signal transmission path;
- said multi-path signal reception apparatus also including second signal reception port apparatus disposed proximate said aircraft and connected with said receiver apparatus within said aircraft by a second signal delay-calibrated signal transmission path;
- said multi-path signal reception apparatus also including third signal reception port apparatus disposed proximate said aircraft and connected with said receiver apparatus within said aircraft by a third signal delay-calibrated signal transmission path;
- said receiver apparatus within said aircraft including time difference of arrival measurement apparatus selectively connecting with said first, second and third signal reception port apparatus by said first path, second path and third path signal delay-calibrated signal transmission paths respectively;
- said time difference of arrival measurement apparatus including angular measurement computation apparatus determining from selected pairs of measured time difference of arrival signals first, second and third angular relationships respectively between said first, second and third signal reception ports of said moving aircraft carrying said airborne signal locating apparatus and said moving airborne signal source;
- said time difference of arrival measurement apparatus further including distance computation apparatus determining from selected pairs of said first, second and third angular relationships a straight line measurement between said moving aircraft carrying said airborne signal locating apparatus and said moving airborne signal source.
The method of determining instantaneous relative position of a physically moving signal source with respect to a physically moving search platform, said method comprising the steps of:
- measuring, using time difference of arrival signals, a first angular relationship between a first portion of said physically moving search platform and said physically moving signal source;
- assessing, using time difference of arrival signals, a second angular relationship between a second portion of said physically moving search platform and said physically moving signal source;
- determining, using time difference of arrival signals, a second angular relationship between a third portion of said physically moving search platform and said physically moving signal source;
- and
- computing from selected of said first angular relationship, said second angular relationship and said third angular relationship azimuth and elevation components of a physical separation distance along a vector connecting said physically moving search platform and said physically moving signal source.
Passive algorithm physically moving signal source relatives locating apparatus comprising the combination of:
- a physically moving locating platform disposed within reception range of said moving signal source;
- multi-path signal reception apparatus disposed in physically segregated locations on said moving platform;
- said multi-path signal reception apparatus including first path signal source to moving platform signal reception apparatus disposed on a first physical portion of said physically moving platform;
- said multi-path signal reception apparatus also including second path signal source to moving platform signal reception apparatus disposed on a displaced second physical-portion of said physically moving platform;
- said multi-path signal reception apparatus further including third path signal source to moving platform signal reception apparatus disposed on an additionally displaced third physical portion of said physically moving platform;
- time difference of arrival measurement apparatus connected with said first path, second path and third path signal source to moving platform signal reception apparatus;
- said time difference of arrival measurement apparatus including angular measurement computation apparatus determining from each measured time difference of arrival signal originating in said first, second and third path signal source to moving platform signal reception apparatus first second and third angular relationships respectively between each said first, second and third physical portions of said physically moving platform and said moving signal source;
- and
- distance computation apparatus determining from said first second and third angular relationships a measure of instantaneous physical distance between said physically moving signal source and said physically moving platform.
Dependencies are inferred from the claim text.