Abstract: To receive data normally in communication by an optical signal by an electronic device which transmits data even when a transmission frequency differs. An electronic device transmits a transmission-frequency measurement signal for measuring a transmission frequency of data and transmits the data by using a light source which transmits an optical signal. An electronic timepiece specifies the transmission frequency of data based on the transmission-frequency measurement signal received by a solar battery which receives the optical signal and receiving the data by the solar battery based on the specified transmission frequency.

Abstract: To make it possible that a user of a fish detector for a fishing from rocks near the shore, which possesses an arm-portable type data display unit, can simply and surely know an approach of a fish shoal. An arm-portable type data display unit possesses a function of judging the approach of the fish shoal by receiving a radio signal from an ultrasonic sensor unit and generating a fish shoal approach signal. The arm-portable type data display unit possesses a vibration type notification section comprising a motor driving circuit and a vibration motor. The arm-portable type data display unit drives the vibration type notification section on the basis of the fish shoal approach signal to give a vibration to the user, thereby notifying the approach of the fish shoal.