| 摘要 |
PURPOSE:To restore a stabilized modulated wave by providing a means which counts a time during gain control is not performed by the first deciding device and outputs a detecting signal when the time exceeds a setting time, and a means which terminates the gain control by a prescribed deciding device when the detecting signal is outputted. CONSTITUTION:When a receiving is started, a level deciding device 7 is operated and either of a high level gain down signal S3 or a high level gain up signal S5 is set as '1' and with operating a gain controller 3, the gain volume of a variable gain amplifier 1 is controlled so that the output level of the variable amplifier 1 is to be a setting level. At the moment when both outputs of the level deciding device 7 are '0's, the output of a NOR gate 11 becomes '1' and a timer 13 starts to count the time. And when the time is exceeded a prescribed setting time, the output of the timer 13 becomes '0' and therefore, AND gates 15 and 17 are closed and the output of an average level deciding device 9 is no more inputted to the gain controller 3 and afterwards, the gain control is no more performed by the average deciding device 9.
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