RFID tag location systems
US9367785B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 18, 2011 |
| Grant date | Jun 14, 2016 |
| Priority date | — |
| Expiry date | Feb 19, 2033 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01S13/878
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
We describe a methods of locating an RFID tag. One method transmits tag location signals at a plurality of different frequencies from a plurality of different antennas spaced apart by more than a near field limit distance. The processing determines a phase difference at the plurality of different frequencies by determining a phase difference between either i) two or more of the transmit signals resulting in a maxima in the returned signal RSSI or ii) a first transmit signal and its corresponding return signal. The range determining uses return signals weighted by signal strength. Further data which may be used for averaging may be generated by using the above techniques along with changes in the polarisation state of the transmit and receive antennas and/or physical reconfiguration of the antennas (e.g. switch the transmit and receive elements).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.