| 摘要 |
PURPOSE: A DTV(Digital Television) receiver using a variable AGC(Automatic Gain Controller) is provided to variably use a gain control reference of an AGC for improving the performance of a DTV receiver in a ghost-existing zone. CONSTITUTION: A DTV receiver using a variable AGC includes a saw filter(20) for changing an amplification of a signal according to the size of the signal input via a tuner(10) by filtering, an intermediate frequency processing part(30) for changing the band of the signal to an intermediate frequency band, and an A/D converter(40) for converting the signal to a digital signal. If an output data from the A/D converter has a difference in the timing by gate delay, a ghost recovery part(50) controls the timing. A DC removing part(60) removes DC components from the data of the ghost recovery part when transmitting the data. A channel equalizer(80) and a synchronizing part(70) searches the existence and the size of the ghost from the DC component-removed signal. An AGC(100) varies a gain control reference value defined in advance by the existence and the size of the ghost, and makes the output data from the A/D converter or the DC removing part to the tuner and the intermediate frequency processing part for gain control. In the existence of the ghost, the AGC reference value is lowered to reduce the size of the input signal of the A/D converter. According to the size of the digital signal, a gain of an amplifier or a damper positioned between the tuner and the intermediate frequency processing part is controlled to the varied AGC reference value.
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