| 摘要 |
PURPOSE:To remove a strain caused by the delay of an auto level controller by modulating an output from a low frequency amplification circuit into a high frequency and controlling the gain of the low frequency amplification circuit with a detection signal in the high frequency level. CONSTITUTION:As for a voice low frequency, the dynamic range of the low frequency is compressed into half in a compressor type amplifier 1 and the average voltage of a low frequency signal is raised by enlarging a small amplitude, moreover it passes through an automatic output control circuit 2 and is mixed with the output from a carrier oscillator 4 by a balanced modulation circuit 3 so as to be converted into a high frequency signal. A part of the output is amplified by a high frequency amplifier 5 and detected by a detector 6, so that a DC voltage corresponding to an input signal is fetched and the gain is controlled by negatively feeding back the detected voltage to the automatic output control circuit 2. Thus, it is not only needless to automatically control the gain on a high frequency amplification side, but also possible to attain the strain under conditions that it does not exceed a specified output power at all.
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