| 摘要 |
PROBLEM TO BE SOLVED: To obtain an optimum AGC characteristic without caring about dispersion in a gain of a tuner and a deviation in a gain between channels by controlling a gain of a plurality of amplifier stages before and after frequency conversion of an input signal into an IF signal in a receiver with an AGC circuit used for a tuner of a digital CATV. SOLUTION: A gain of an RF AGC amplifier in a tuner and a gain of an IF AGC amplifier 3 that are used for AGC are controlled respectively by respective control signals so that an input to an A/D converter 7 before digital demodulation is controlled constant. A level detection section 9 of the receiver detects a level of the input signal A/D-converted by the A/D converter 7, each control signal required for the gain control is obtained through an arithmetic processing, and D/A-converted respectively by D/A converters 11, 12 and fed to the tuner 1 and the IF AGC amplifier 3. |
