| 摘要 |
PROBLEM TO BE SOLVED: To receive a signal satisfactorily, respectively at a place such as a tunnel where the reception state is very poor and at a place where the reception state is comparatively satisfactory. SOLUTION: This receiver is provided with a sensitivity sensor (19), that senses the sensitivity of a signal received by reception means 15-18, an illuminance sensor 30 that detects the lightness around itself, and amplifier means 12, 13, 14 that increase a gain of the signal received by the reception means 15-18, when a derivative value of an illuminance change sensed by the illuminance sensor 30 is a prescribed level or over and the sensitivity sensor senses a reduction in the reception sensitivity.
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