| 摘要 |
PROBLEM TO BE SOLVED: To switch receiving channels by determining if recovery is to be made when broadcast quality deteriorates. SOLUTION: A channel switching control section 101 determines that deterioration in broadcast quality is caused by shut-off of received radio wave when a time-varying amount of AGC voltage is increased to a first threshold or more, so that it holds a receiving channel. When the AGC voltage is kept equal to or higher than a second threshold for a first predetermined switching time after the increase of the time-varying amount to the first threshold or more, the control section 101 switches receiving channels even if deterioration in broadcast quality is caused by shut-off of received radio wave. When the AGC voltage is kept increased for a second predetermined switching time or more while the time-varying amount of the AGC voltage is less than the first threshold, the control section 101 determines that deterioration in broadcast quality is caused by a move of a vehicle, so that it switches receiving channels. COPYRIGHT: (C)2007,JPO&INPIT
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