Abstract: A vibration detection system comprises a battery-less vibration sensor and an interrogator. The sensor comprises a single port surface acoustic wave resonator. The interrogator continuously transmits a carrier wave signal to the resonator while receiving a wave signal reflected from the resonator. The reflected wave signal includes components other than the transmitted carrier wave signal if the sensor senses a vibration event. Based the reflected wave signal, the interrogator judges whether the vibration event occurs.

Abstract: Provided are a multiplexing circuit for multiplexing a memory output signal output by a memory for temporarily accumulating a low-order group signal with an overhead bit necessary for optical digital transmission and a pattern generation circuit for generating an unfixed pattern having no fixed value. An unfixed pattern is applied to the multiplexing circuit while the memory outputs a fixed pattern. A selection circuit provided between the multiplexing circuit and the memory selects an unfixed pattern between a fixed pattern output by the memory and an unfixed pattern output by the pattern generation circuit.

Abstract: Provided are a multiplexing circuit for multiplexing a memory output signal output by a memory for temporarily accumulating a low-order group signal with an overhead bit necessary for optical digital transmission and a pattern generation circuit for generating an unfixed pattern having no fixed value. An unfixed pattern is applied to the multiplexing circuit while the memory outputs a fixed pattern. A selection circuit provided between the multiplexing circuit and the memory selects an unfixed pattern between a fixed pattern output by the memory and an unfixed pattern output by the pattern generation circuit.