Thomson Licensing

Thomas Licensing S.a.

Adolf DSouza

An equalizer () and a prefilter () used in conjunction with a comb filter () in a High Definition Television (HDTV) system. The prefilter () may be placed before the comb filter (), or alternatively may be placed after the comb filter. Further, the method may be enhanced by estimating the filter tap when the prefilter () is placed after the comb filter (). The equalizer () produces a fifteen level output from the eight level Vestigial Sideband (VSB) input without limiting the amplitude at symbol 12 to a relatively small value, such as &#x2212;20 dB. Three specific methods of increasing the permissible amplitude at symbol 12 are presented which permit tap 12 amplitudes as high as &#x2212;6 dB.

Equalizer system including a comb filter in an HDTV system

A method and apparatus for equalizing a signal containing high definition television information in the presence of co-channel NTSC interference employs an equalizer having feed forward and decision feedback filters. A comb filter is inserted ahead of the equalizer when NTSC co-channel interference is present. A selected tap of the decision feedback filter is set to a zero value when the signal is being equalized during an intitial blind operating mode. The decision feedback filter taps are updated afterwards, in a decision-directed operating mode.

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Westfield, IN, United States of America

Adolf DSouza