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Digital video signal processor with distortion correction

  • US 4,199,656 A
  • Filed: 04/23/1976
  • Issued: 04/22/1980
  • Est. Priority Date: 09/10/1975
  • Status: Expired due to Term
First Claim
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1. An apparatus for compensating for signal distortions in an input digital signal comprising a plurality of ones and zeros defining an information content for said input digital signal, said input digital signal having associated peak-to-peak signal levels, respectively, defining said ones and zeros wherein said signal distortions in said input digital signal comprise said respective peak-to-peak signal levels associated with at least some of said plurality of ones and zeros comprising said input digital signal differing from said respective peak-to-peak signal levels associated with others of said plurality of ones and zeros comprising said input digital signal, said peak-to-peak signal levels of said input digital signal resulting from zero-to-one and one-to-zero transitions in said input digital signal, said compensating apparatus providing a compensated output digital signal from said distorted input digital signal having the same information content as said input digital signal defined information content, said plurality of ones and said plurality of zeros comprising said compensation output digital signal all having the same respective peak-to-peak signal levels varying about a common base level, said compensating apparatus comprising means for tracking said zero-to-one and one-to-zero transitions in said input digital signal, first means operatively connected to said tracking means and responsive to each tracked zero-to-one transition in the peak-to-peak signal level of said input digital signal for clamping the level of said zero-to-one transition at a first predetermined signal level irrespective of any continued rise in said level of said distorted input digital signal zero-to-one transition and maintaining said clamped zero-to-one transition at said first predetermined signal level until the presence of a subsequent one-to-zero transition in said distorted input digital signal is detected whereby said signal level becomes unclamped, said tracking means tracking said subsequent one-to-zero transition in said unclamped signal, and second means operatively connected to said tracking means and responsive to said tracked subsequent one-to-zero transition for said unclamped signal for reclamping the level of said tracked subsequent one-to-zero transition at a second predetermined signal level irrespective of any continued fall in said level of said distorted input digital signal subsequent one-to-zero transition until the presence of a subsequent zero-to-one transition in said distorted input digital signal is detected whereby said signal level of said reclamped signal again becomes unclamped, whereby said compensated output digital signal is provided from said distorted input signal.

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