To shorten a period necessary for a plurality of photosensors arranged in a display and data input region to receive light. The non-volatile MOS transistor may be a floating gate transistor, such as a flash transistor, or may be another type of non-volatile transistor such as a floating charge-trapping SONOS, MONOS transistor, or a nano-crystal transistor. The sectional discrimination logic unit discriminates the sectional temperatures based on temperatures where an output of the variable delay cell meets each of outputs of the fixed delay cells according to the change in the temperature, and generates temperature codes corresponding to the sectional temperatures. The method also includes determining a communication signal encoded in the backscattered light based on the difference, where the communication signal is encoded in the backscattered light responsive to mechanical waves applied to the optical fiber at a location remote from the phase-sensitive OTDR device.