| 摘要 |
PROBLEM TO BE SOLVED: To always ensure a satisfactory receiving state depending on changes in a radio wave environment during traveling. SOLUTION: An on-board antenna amplifier device is connected between an antenna 10 and a digital television tuner 11, and is provided with an attenuator for adjusting received signals at a predetermined level and an amplifier. The device includes a switching circuit 15 for switching an attenuation rate of the attenuator or an amplification rate of the amplifier into a plurality of steps, and a gain control means 17 for controlling the switching circuit 15 so that it switches in a predetermined switching order on the basis of the receiving level information of a predetermined desired wave and an interference wave against the desired wave. COPYRIGHT: (C)2007,JPO&INPIT
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