Apparatus and method for interrogating a passive sensor
US6765493B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 25, 2002 |
| Grant date | Jul 20, 2004 |
| Priority date | — |
| Expiry date | Feb 25, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01D5/48
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Apparatus for determining the resonant frequency of a passive sensor, for example a saw device, includes a device (5, 7, 3) for transmitting signals of a plurality of frequencies to the passive sensor (2); a device (3, 7) for receiving signals from the passive sensor simultaneously with the transmitting of signals; a device (7) for comparing the received signals with the transmitted signals to identify a characteristic change in the relationship between the received signals and the transmitted signals which occurs when the sensor is being driven at its resonant frequency. As the frequency at which the passive sensor is driven passes through the resonant frequency of the sensor the phase and/or amplitude of the signal generated by the passive sensor will change. By identifying this change of phase and/or amplitude the point at which resonance occurs can be detected. The frequency of the transmitted signal at the moment when the comparison indicates that the sensor is being driven at its resonant frequency is the resonant frequency of the sensor.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.