The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 31, 2004
Filed:
Dec. 20, 2002
Walter Hirt, Wettswil, CH;
International Business Machines Corporation, Armonk, NY (US);
Abstract
The present invention provides an apparatus, method, and system for determining a time of arrival (TOA) and time differences of arrival (TDOA) of a transmitted signal {S} receivable at different locations of known spatial coordinates. The system comprises a first transmitter with a respective antenna feed point positioned at an a priori unknown location P and emitting a first signal {S}. The system includes furthermore a set of transceivers or transponder units comprising first receivers for receiving first signals {S} by means of respective antennas with feed points located at known locations L . Such system also comprises second transmitters emitting respective derived second signals {{tilde over (S)} } after known and scheduled respective time intervals &dgr; as measurable between the feed points of said respective first receiving antennas located at known locations L and respective second transmitting antenna located at locations L′ . A set of second receivers receives respective second signals {{tilde over (S)} } after known respective time intervals &tgr; measured between the feed points of the second transmitting antennas and feed points of second receiving antennas. A controller terminates the measurement cycle for each first transmitter to define total signal transfer times and then sends to a processing unit an ensemble of derived third signals {Ŝ }, after some known respective delay times &Dgr;T . Said delay times &Dgr;T are measured between the time one third signal {Ŝ} passes the feed point of the respective second receiving antenna and the time instant where the respective single time reference T issued by the controller terminates the measurement cycle. The set of third signals {Ŝ } received by the processing unit contains sufficient information for determining the time of arrival (TOA) and time differences of arrival (TDOA) and to compute {circumflex over (P)}, an estimate of the a priori unknown location P of a mobile radio terminal or radio tag emitting the first signal {S}.