| 摘要 |
There is described a sensor for sensing the parameter, the sensor comprising a transmit aerial, an intermediate coupling element, a receive aerial electromagnetically coupled to the transmit aerial via the intermediate coupling element, a signal generator operable to generate a periodic excitation signal at a first frequency, and arranged to apply the generated excitation signal to the transmit aerial in order to generate a sense signal in the receive aerial indicative of the value of the parameter to be measured and a signal processor operable to process the signal induced in the receive aerial to determine a value representative of the parameter being measured. The intermediate coupling element includes a frequency shifter which, in response to the periodic excitation signal being applied to the transmit aerial, generates a sense signal in the receive aerial having a signal component at a second frequency which is different from the first frequency, and the signal processor is operable to process the signal at the second frequency to determine the value representative of the parameter being measured.
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