Distance measuring apparatus, distance measuring method, reflector and communication system
US7649491B2 · kind B2 · utility
29Cited by
0References
22Claims
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Key dates
| Filing date | Sep 1, 2005 |
| Grant date | Jan 19, 2010 |
| Priority date | — |
| Expiry date | Nov 1, 2025 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01S13/38
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A transmission controller 7B is configured to transmit an R/W request signal for requesting transmission of a tag response signal to a RFID tag 1 twice. At this time, a frequency controller 7A controls a PLL section 5A to transmit the R/W request signal via different carrier frequencies. A phase information acquirer 8A detects a phase change amount of the tag response signal that is transmitted via different carrier frequencies. A distance calculator 8B calculates the distance between the reader/writer 2 and the RFID tag 1 on the basis of the phase change amount.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.