Multi-level RF identification system
US6765476B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 9, 2001 |
| Grant date | Jul 20, 2004 |
| Priority date | — |
| Expiry date | Jun 28, 2021 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06K7/0008
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A radio frequency identification system having a radio frequency transceiver for generating a continuous wave RF interrogation signal that impinges upon an RF identification tag. An oscillation circuit in the RF identification tag modulates the interrogation signal with a subcarrier of a predetermined frequency and modulates the frequency-modulated signal back to the transmitting interrogator. The interrogator recovers and analyzes the subcarrier signal and determines its frequency. The interrogator generates an output indicative of the frequency of the subcarrier frequency, thereby identifying the responding RFID tag as one of a “class” of RFID tags configured to respond with a subcarrier signal of a predetermined frequency.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.