| 摘要 |
PURPOSE: A digital TV relay and an automatic gain control circuit for the digital TV relay are provided to maintain a high carrier-to-noise ratio to improve broadcasting quality while keeping a uniform output level of digital TV broadcast. CONSTITUTION: At least one variable attenuator is included in each of a down-converter and an IF amplifier. An automatic gain control circuit differently controls gain control voltages applied to the variable attenuators by stages so that outputs and inputs of amplifiers included in a digital TV relay are not excessively increased or decreased to prevent carrier-to-noise ratio from being deteriorated.
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