| 摘要 |
PURPOSE:To widen the dynamic range of a display drive circuit by using an output DC voltage from a level detector for controlling a gain of a high frequency amplifier circuit section to control an input signal level display drive circuit. CONSTITUTION:An output of a high frequency amplifier circuit section 1 is given to a mixing circuit 2 and its output is given to intermediate frequency amplifier circuit sections 4, 5 in this order. An input carrier signal extracted from the intermediate frequency amplifier circuit section 4 is detected for the level by a level detector 6, and its output voltage is fed to a gain control circuit 7 for the high frequency amplifier circuit and also given to the input signal level display drive circuit 9 as the drive voltage.
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