| 摘要 |
PURPOSE:To reduce the power consumption of a mobile object side by calibrating a clock of each mobile object with time information inserted to a message sent from a communication center at a prescribed time interval and making the receiver of each mobile object inactive till a prescribed time zone when a message to be received next is sent. CONSTITUTION:A clock calibration message is sent to all mobile stations at every, e.g., noon by using a global address. Then each mobile station calibrates the clock based on the calibration message and receives intermittently a designated message addressed to itself. When the clock matching is finished, a timing to turn on a switch 14 is calculated from the present time of the clock 23 and a prescribed transmission time of the calibration message or the designated message and in this state, the mobile station awaits the timing when the time reaches that for the calibration message or the designated message. If not finished, the clock matching is executed. |
