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:
Dec. 05, 2000
Filed:
Aug. 30, 1995
Max B Frederick, Arnold, CA (US);
Corsair Communications, Inc., Palo Alto, CA (US);
Abstract
A transmitter identification system to determine if cellular phones in a cellular phone system are authorized as distinguished from cloned phones, operated by fraudulent users, that are unauthorized. Components used in the manufacture of cellular phones vary slightly from one phone to anther so that, when the phones are used, the transmitter signals from each phone have different external signal traits. For each cellular phone call, the transmitter signal is received and characterized using a received set of features resulting from the external signal traits. The received set of features is compared with previously stored sets of Features in a database to determine if the call is authorized or unauthorized and, if unauthorized, the call is stopped and access to the fraudulent user is denied.