Method and system for detecting a marker
US5414410A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 10, 1994 |
| Grant date | May 9, 1995 |
| Priority date | — |
| Expiry date | Feb 10, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG08B13/2474
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
An electronic article surveillance system is provided having a transmitter for generating two alternating magnetic fields by way of a single transmitter coil fed with a transmitter signal current, and a receiver that detects harmonics and intermodulation products of the alternating magnetic fields by way of a receiver coil that generates a receiver signal current. The receiver comprises a wide-bandwidth phase detector locked on to a frequency p.f.sub.2 .+-.q.f.sub.1, where p and q are positive integers, one of which may be zero, and a digital signal processor adapted to carry out a full time-domain analysis of the waveform of the receiver signal current, and wherein the transmitter signal current corresponds to the linear super position of two alternative currents with a relatively low frequency f.sub.1 and high frequency f.sub.2 respectively.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.