05448760 is referenced by 70 patents and cites 21 patents.

Authorized use of a wireless subscriber system, e.g. cellular telephone system, is distinguished from unauthorized use by electronically observing a plurality of external signal traits which represent alterations in the radio frequency signal due to physical characteristics identified with a particular transmitter. Examples of such external signal traits include those which are produced as a consequence of manipulating the carrier to encode information upon it and those produced by transmitter timing circuit idiosyncrasies. The external signal traits are converted into a signature code or security pattern which is then stored along with the existing subscriber system identification code to generate a historic security pattern database for use in subsequent authorized use validation.

Title
Cellular telephone anti-fraud system
Application Number
8/74083
Publication Number
5448760
Application Date
June 8, 1993
Publication Date
September 5, 1995
Inventor
Max B Frederick
Arnold
CA, US
Agent
Harness Dickey & Pierce
Assignee
Corsair Communications
CA, US
IPC
H04B 7/00
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