Wireless sensor reader

摘要

A wireless sensor reader is provided to interface with a wireless sensor. The wireless sensor reader transmits an excitation pulse to cause the wireless sensor to generate a ring signal. The wireless sensor reader receives and amplifies the ring signal and sends the signal to a phase-locked loop. A voltage-controlled oscillator in the phase-locked loop locks onto the ring signal frequency and generates a count signal at a frequency related to the ring signal frequency. The voltage-controlled oscillator is placed into a hold mode where the control voltage is maintained constant to allow the count signal frequency to be determined.

主权项

1. A method of obtaining a measurement from a remote location, the method comprising:
transmitting a plurality of excitation pulses each at a predetermined frequency to a wireless sensor wherein said predetermined frequency is determined during a period of time when said wireless sensor is not being sampled wherein each excitation pulse is transmitted at the predetermined frequency; receiving a signal from said wireless sensor in response to said plurality of excitation pulses; sampling and holding said received signal; and ascertaining the frequency of said received signal; wherein said wireless sensor is configured to change its resonant frequency in proportion to at least one sensed parameter.