Very low frequency tracking system
US5339074A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 13, 1991 |
| Grant date | Aug 16, 1994 |
| Priority date | — |
| Expiry date | Sep 13, 2011 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG07C9/28
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
Apparatus identifying an instrumentality such as a person's hand or an article of merchandise, wherein the instrumentality carries a tag incorporating a transponder generating and transmitting a radio frequency identification signal in response to a radio frequency transmitted inquiry, a nest comprising an identifying station and incorporating a proximity sensor sensing the presence of the instrumentality at the identifying station and producing an indication of the presence or absence of the instrumentality, the identifying station comprising a radio frequency sensor portion generating a radio frequency transmitted inquiry transmitted to the transponder in response to sensing the presence of the instrumentality and receiving the radio frequency identification signal from the transponder, the proximity sensor terminating generation of the radio frequency transmitted inquiry when a clear and reliable output indication identifying the tag has been produced, and the proximity sensor also preventing, after producing a clear and reliable output indication, generation of a subsequent radio frequency transmitted inquiry until the proximity sensor has subsequently produced indications of t…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.