Patent ID: 7696867

Claim:
A sensor node comprising: a control unit for obtaining information by driving sensor being comprised in said control unit; a radio communication unit for transmitting information acquired by said control unit; and a battery for supplying said control unit, radio communication unit and sensor with electric power, wherein said control unit further comprises: a clock supplying unit for supplying said control unit with clocks at a predetermined clock frequency; a standby control unit for repeating at a predetermined cycle an operational state in which clocks of the predetermined frequency are supplied from said clock supply unit and a standby state during which the clock is suspended or the clock frequency is reduced during a predetermined measurement period; a sensor control unit for starting the supply of electric power to said sensor when said predetermined measurement period starts, maintaining the power supply to the sensor even if the control unit is standing by during said predetermined measurement period, and cutting off the supply of power to the sensor when said predetermined measurement period end; and a measurement unit for acquiring information from said sensor every time when said control unit starts operating, wherein said clock supplying unit lowers the clock frequency due to be supplied to said control unit when said radio communication unit is shifted to the operational state.