Access control equipment and method for using the same
US5339073A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 25, 1991 |
| Grant date | Aug 16, 1994 |
| Priority date | — |
| Expiry date | Mar 25, 2011 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG07C9/29
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
Access control equipment includes an interrogation unit which emits an interrogation signal, and a plurality of transponders, each transponder having a stored identity code different from that of the other transponders. This identity code includes a plurality of fields each holding a selected information bit. The interrogation signal is controlled so as simultaneously to interrogate the fields of all transponders within range in a serial manner. A group reply signal is sent back to the interrogation unit from any transponder having, in the field being interrogated, a bit matching that required by the interrogation signal. The interrogation unit is arranged to determine, from the series of received reply signals, the identity of each and every valid transponder within range.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.