| 摘要 |
PROBLEM TO BE SOLVED: To improve reception quality of a plurality of channels by reducing a difference in level between high frequency signals of each of channels by AGC in extracting the high frequency signals of a plurality of channels from a received signal. SOLUTION: An RF filter 1a extracts high frequency signals of a plurality of channels included in a reception wave Sin, and a signal Scp level-adjusted by a variable filter circuit 1b is supplied to an RF amplifier 4. A frequency selecting circuit 2c sets the bandwidth of the variable filter circuit 1b at a selection band width BWi of a channel corresponding to a large level in detection level signals Sdc1, Sdc2 and Sdcn in each demodulation processing system, and a gain control circuit 2a sets the attenuation quantity in the selection bandwidth BWi at an attenuation quantityαj corresponding to the large level. The variable filter circuit 1b attenuates a high frequency signal passing through the selection bandwidth BWi, of the high-frequency signals of the plurality of channels extracted in the RF filter 1a, at the attenuation quantityαj, thereby adjusting to reduce the difference in level of high frequency signals of the plurality of channels. COPYRIGHT: (C)2008,JPO&INPIT
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