AUTOMATIC FINE TUNING APPARATUS FOR A DIGITAL TELEVISION CAPABLE OF CONTROLLING THE TUNING FREQUENCY OF THE TUNER AT A DEMODULATING STAGE

摘要

PURPOSE: An automatic fine tuning apparatus for a digital television is provided to control the tuning frequency of the tuner at a demodulating stage although the central frequencies of a channel and of a signal tuned by the tuner are out of a permitted limit. CONSTITUTION: A demodulator(200) comprises an NTSC(National Television Standards Committee) remove filter(230) and an equalizer(250), processes a central frequency of an IF(Intermediate Frequency) signal outputted from a tuner(100) and checks a lock of a channel. When the channel is locked, the demodulator demodulates the IF signal and then outputs the IF signal into data bit stream. A power detecting member(300) detects power outputted from the NTSC remove filter and equalizer. A microcomputer(400) control the central frequency detected by the tuner on the basis of the channel lock check result and power values detected by the power detecting member.