Digital demodulator with a unit for correcting over modulation and preventing black reversing

Claim 1

A digital demodulator comprising: a reproducing head for reproducing an analog video signal from a recording medium; an analog to digital converter for converting the analog video signal from said reproducing head into a digital signal; a Hilbert transform circuit for transforming the digital signal into transformed signals whose phases are shifted by first and second angles from a phase of the digital signal, respectively; a frequency detector for detecting a frequency of the transformed signals; first coefficient calculation means for producing a weighting coefficient from an output signal of said frequency detector; second coefficient calculation means for producing a weighting coefficient from the transformed signals; a multiplier for multiplying together the weighting coefficients from said first and second coefficient calculation means and producing a correction signal; an equalizer receiving said correction signal and said transformed signals for correcting a frequency characteristic of the transformed signals in response to said correction signal; and a demodulator for demodulating an output signal of said equalizer, wherein the frequency characteristic of said equalizer is corrected in accordance with said correction signal from said multiplier.