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US 4,561,012 AGranted
Pre-emphasis and de-emphasis filters for a composite NTSC format video signal
AssigneeRCA Corporation
InventorAlfonse Acampora
Life of this patent
Estimating the term…
Abstract
Phase reversal of solely the chrominance component of only alternate frames of an NTSC format signal prior to pre-emphasis and again subsequent to de-emphasis permits simpler and less costly filter structure to be employed without any loss of filtering capability.
Claims7
A transmitter for use in a television signal communication system comprising said transmitter and a receiver;
- wherein said transmitter includes translation means for deriving a communication signal communicated to said receiver in response to the application thereto of a composite NTSC format video signal of a two-dimensional image of picture elements (pixels) that are repetitively scanned at the NTSC predetermined frame rate, whereby stationary portions of said image result in a video signal luminance component that recurs at said predetermined frame rate and a video signal chrominance component that recurs only at one-half said predetermined frame rate;
- said transmitter translation means comprising:
- first means for modifying said video signal by phase inverting solely the NTSC color carrier and phase-modulated chrominance component of each of alternate frames of said video signal, thereby providing substantially the same phase for the chrominance component of each of said alternate frames as for the chrominance component of each of the remaining frames of said video signal;
- and
- second means including a pre-emphasis comb filter coupled to said first means and responsive to said modified video signal for deriving an output in which those frequency components of said modified video signal which are equal to odd integral multiples of half said predetermined frame rate are pre-emphasized with respect to those frequency components of said modified video signal which are equal to even integral multiples of half said predetermined frame rate.
2 more elements
A receiver for use in a television signal communication system comprising a transmitter and said receiver;
- wherein said transmitter transmits a signal communicated to said receiver that in translated format manifests a composite NTSC format video signal of a two-dimensional image of picture elements (pixels) that are repetitively scanned at the NTSC predetermined frame rate;
- said translated format including (1) the phase inversion of solely the NTSC color carrier and phase-modulated chrominance component of each of alternate frames of said NTSC format video signal to thereby provide substantially the same phase for the chrominance component of each of said alternate frames as for the chrominance component of each of the remaining frames of said NTSC format video signal;
- and (2) the pre-emphasis in accordance with a given pre-emphasis characteristic of those frequency components of both said alternate and remaining frames of said translated format which are equal to odd integral multiples of half said predetermined frame rate with respect to those frequency components of both said alternate and remaining frames of said translation format which are equal to even integral multiples of half said predetermined frame rate;
- said receiver including translation means for translating said translated format back into composite NTSC format that is comprised of:
- first means including a de-emphasis comb filter responsive to said translated format signal communicated to said receiver for deriving an output from said first means in which those frequency components of both said alternate and remaining frames of said translated format which are equal to odd integral multiples of half said predetermined frame rate are de-emphasized, in accordance with a de-emphasis characteristic which is substantially complementary to said given pre-emphasis characteristic, with respect to those frequency components of both said alternate and remaining frames of said translated format which are equal to even integral multiples of half said predetermined frame rate;
- and
- second means coupled to said first means and responsive to the output therefrom for relatively phase inverting solely the color carrier and phase-modulated chrominance component of said respective alternate frames with respect to solely the color carrier and phase-modulated chrominance component of said respective remaining frames, thereby to provide a composite NTSC format video signal output from said second means.
4 more elements
Dependencies are inferred from the claim text.