Cellular telephone anti-fraud system
US5448760A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 8, 1993 |
| Grant date | Sep 5, 1995 |
| Priority date | — |
| Expiry date | Jun 8, 2013 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04W12/72
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.