Equalizer system including a comb filter in an HDTV system
AssigneeThomson Licensing
InventorAdolf DSouza
Life of this patent
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Abstract
An equalizer (34) and a prefilter (1) used in conjunction with a comb filter (2) in a High Definition Television (HDTV) system. The prefilter (1) may be placed before the comb filter (2), or alternatively may be placed after the comb filter. Further, the method may be enhanced by estimating the filter tap when the prefilter (1) is placed after the comb filter (2). The equalizer (34) 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 −20 dB. Three specific methods of increasing the permissible amplitude at symbol 12 are presented which permit tap 12 amplitudes as high as −6 dB.
Claims20
In a system for processing a video data signal comprising a sequence of symbols possibly including an interfering signal, an apparatus for providing an output signal having a desired characteristic, comprising:
- means for detecting (16) the interfering signal;
- a first filter (2) responsive to said interfering signal, said first filter tending to attenuate the interfering signal;
- means for predicting (1) a characteristic of said video data signal and generating a modified signal in response to said characteristic;
- and
- means (34) responsive to said first filter (2) and said means for predicting (1) a characteristic of said video data for providing an equalized output signal.
In a system for processing video data signal comprising groups of encoded data packets containing a plurality of symbols and possibly containing an interfering signal, a method of obtaining a desired signal characteristic comprising the steps of:
- detecting the interfering signal;
- filtering the interfering signal;
- generating a filter output signal in response to said filtering;
- predicting a characteristic of said video data signal from said filter output signal;
- generating a modified signal in response to said characteristic of said video data signal;
- and
- equalizing the filter output signal and the modified signal so as to obtain the desired signal characteristic.
An equalizing and filtering system for processing video data encoded symbols, comprising:
- an input signal, the input signal comprising multiple level vestigial sideband (VSB) symbols;
- a prediction filter (1), the prediction filter being responsive to the input signal and an interfering signal, the prediction filter being adapted to minimize an amplitude associated with a selected symbol
- a comb filter (2), the comb filter being responsive to an output signal generated by the prediction filter (1);
- and
- an equalizer (34), the equalizer (34) producing a signal having relatively more levels than the multiple level VSB symbol input signal.
An equalizing and filtering system for processing video data encoded symbols, comprising:
- an input signal source, the input signal comprising multiple level vestigial sideband (VSB) symbols and containing a desired signal and an interfering signal;
- a comb filter (2), the comb filter being responsive to the input signal, the comb filter (2) generating an output signal having an attenuated interfering signal;
- a prediction filter (1), the prediction filter being responsive to the output signal generated by the comb filter (2), the prediction filter being adapted to minimize an amplitude associated with a selected symbol;
- and
- an equalizer (34), the equalizer (34) producing a signal having relatively more levels than the multiple level VSB symbol input signal.
Dependencies are inferred from the claim text.