| 摘要 |
PURPOSE: The automatic gain control (AGC) of HDTV is provided to improve the SNR (signal to noise ratio) character through applying a gain control using AGC1 (GCA) in the state of maintaining the AGC of a tuner as maximum as possible. CONSTITUTION: The method of controlling the automatic gain of HDTV consists of the following procedures; the first procedure which initializes an automatic gain control signal (AGC2) of a tuner and the control signal (AGC1) of a gain control amplifier (GCA) in case of a reset, after deciding the on or off of a reset in the start mode at the power on or the reset; the second procedure which moves to an operation controlling a gain in the automatic gain controller of the tuner in a fixed state of AGC1, when, controlling the gain of a gain control amplifier, the gain control value becomes the limit of a gain decrease, after being completed the action of a start up mode; the third procedure which, in case of the reset from searching the reset in the state entering to an action controlling the gain in AGCer of tuner, returns to the procedure initializing the AGC2 of the first procedure and AGC1 of GCA and, not in case of the reset, returns to the second procedure controlling the gain of GCA in the state to control the gain of a tuner to the greatest value,
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