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:
Mar. 07, 2000
Filed:
Jun. 27, 1996
David N Hoogerwerf, Everett, WA (US);
Evan R Green, Bothell, WA (US);
David M Stanhope, Tacoma, WA (US);
Randy McKernan, Graton, CA (US);
Cellular Technical Services Company, Inc., Seattle, WA (US);
Abstract
A method and system for actively and rapidly collecting reference waveforms from a large number of cellular telephones is provided. The reference waveforms are used to generate fingerprints which are used to distinguish between authorized cellular telephones and unauthorized cellular telephones. Initially, the system selects a cellular telephone whose reference waveform is desired. The selected cellular telephone is then sent a polling message such as a page or registration request. The cellular telephone receives the polling message and transmits a radio frequency (RF) signal containing a reference waveform that contains certain transmission characteristics unique to the selected cellular telephone. From the received RF signal, the reference waveform is extracted and stored. Preferably, the selected cellular telephone is polled repeatedly in order to receive a sufficiently large number of reference waveforms to be able to generate an accurate fingerprint. One method of polling the cellular telephone is by calling the selected cellular telephone through a cellular telephone system. Another method of polling the cellular telephone is by transmitting a control message such as a page, registration, audit or maintenance message.