Patent ID: 7176810

Claim:
An on-vehicle DSRC apparatus employed for a dedicated short-range communication in an intelligent transport system, comprising: a radio unit for performing communication with an on-road radio equipment installed at a location associated with a road; a data processing unit for processing data received from said radio unit; a battery for supplying an electric power to said radio unit and said data processing unit; and a first power switch inserted in a power supply line extending between said battery on one hand and said radio unit and said data processing unit on the other hand, wherein said first power switch is imparted with a function for effectuating a power save for control for the power supply from said battery so that electric energy of said battery can be saved, said on-vehicle DSRC apparatus further comprising: an electric field intensity detecting circuit for detecting a field intensity of radio wave transmitted from said on-road radio equipment; an activating circuit for activating said first power switch when a detection output of said electric field intensity detecting circuit becomes higher than a predetermined level inclusive thereof; a second power switch inserted in a power supply line extending between said battery and said electric field intensity detecting circuit for controlling the power supply to said electric field intensity detecting circuit from said battery; and a first timer for intermittently driving said second power switch.