US 5,343,212 AGranted

(AOA/LBI) emitter ranging method and apparatus

AssigneeLitton Industries, Inc.

InventorsConrad M. Rose, Jeffrey J. Drude

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Abstract

An Angle of Arrival/Long Baseline Interferometer (AOA/LBI) passive ranging apparatus and method for emitter range determination can use any convenient airframe location for the two-antenna uncalibrated LBI baseline. This baseline has a theoretically unlimited length and does not require a specific SBI/LBI baseline ratio. Only a single initial AOA is required. Range partitions are formed along the single AOA. The emitter is assumed to lie in any of N range bins and the corresponding DOA (direction of arrival) unit vectors computed. Each of these DOA unit vectors is then used to predict the LBI phase differential and the N resolved LBI phases each drive a location estimator. The location estimator (filter) with consistent output provide the emitter range. The LBI range from these filters is used for subsequent DOA generation and ambiguity resolution.

Claims11

Dependent claims

A method for determining an emitter range using a long baseline interferometer (LBI), comprising the steps of:

(i) determining a single angle of arrival (AOA) of an emitter signal with an AOA detection device and outputting an AOA signal;
(ii) generating a plurality of initial range partitions, each partition having an initial assumed emitter position along said angle of arrival, using said AOA signal output from said AOA detection device;
(iii) performing an initial prediction of phase change of said emitter signal between elements of said LBI based on said initial plurality of assumed emitter positions;
(iv) measuring sequential LBI phase changes with phase change circuitry, said circuitry receiving emitter signals from said elements of said LBI;
(v) differentially resolving each of said measured LBI phase changes with said predicted LBI phase changes and generating a plurality of resolved phase signals, thereby providing an azimuth for each of said partitions;
(vi) at each measured phase change, generating a signal representing an estimated emitter location for each of said assumed emitter positions;
(vii) predicting subsequent LBI phase changes for each said estimated emitter location using said estimated emitter location;
(viii) differentially resolving said measured LBI phase changes with said subsequent LBI phase changes, generating a new azimuth for each partition and repeating steps vi, vii and viii, until a predetermined range criterion is met;
and
(ix) generating a signal indicating a best range estimate as the emitter location from the plurality of estimated emitter locations generated.

7 more elements

Dependencies are inferred from the claim text.