Patent ID: 8908468

Claim:
A wireless remote sensing system comprising; a carrier wave generator configured to generate a carrier wave of a predetermined frequency; a first switch configured to switch between an ON state and an OFF state, the ON state allowing the first switch to generate a transmission signal of the predetermined frequency by pulse modulating the carrier wave received from the carrier wave generator; a surface acoustic wave sensor having a predetermined delay time and configured to receive the transmission signal of the predetermined frequency, the surface acoustic wave sensor outputting and transmitting a reception signal of the predetermined frequency after the delay time has elapsed from receipt of the transmission signal; a second switch configured to switch between an input state and an output state, the input state allowing the second switch to receive the transmission signal from the first switch in the ON state and to transmit the transmission signal to the surface acoustic wave sensor, the output state allowing the second switch to receive the reception signal from the surface acoustic wave sensor and to output the reception signal; a surface acoustic wave delay element having the same delay time as the surface acoustic wave sensor and including an input electrode for receiving the transmission signal from the first switch in the ON state and an output electrode for receiving a surface acoustic wave from the input electrode, the surface acoustic wave delay element configured to output a local signal of the predetermined frequency from the output electrode after the delay time has elapsed from receipt of the transmission signal by the input electrode, and a mixer configured to receive the reception signal from the second switch and the local signal from the surface acoustic wave delay element, the mixer configured to generate a synchronous detection signal by mixing the reception signal and the local signal, wherein the second switch and the mixer are implemented on one chip of a semiconductor substrate, during a period of time when the second switch remains in the input state, the first switch switches from the OFF state to the ON state and then switches back to the OFF state, and the second switch switches from the input state to the output state before the delay time has elapsed after the first switch switches back to the OFF state.