US 4,400,718 A · Digital television transmission using chrominance inversion

Abstract

At a transmitter, an analog NTSC color video signal is converted into a digital video signal and all of the signal components in the chrominance spectral band in alternate television frames are inverted. The resultant signal is transmitted via a low-speed digital signal transmission channel using interframe difference coding. At a receiver, the received digital signal is converted into an analog video signal and all of the signal components in the chrominance spectral band in the other alternate television frames are inverted. The resultant signal, having inverted chrominance, is reproduced on a conventional NTSC color television receiver. Bandpass and comb filtering, preferably on the digital signals, are used at the transmitter and at the receiver to separate the luminance and chrominance signal components to enable inversion of the chrominance components.

Claims6

Dependent claims

A method of transmitting an NTSC colour video signal via a digital signal transmission channel, comprising the steps of:

inverting components of said video signal in the chrominance spectral band in alternate television frames to produce an alternate-frame chrominance-inverted video signal;
transmitting said alternate-frame chrominance-inverted video signal via said digital signal transmission channel in the form of a digital signal encoded using interframe difference coding at a transmitter and decoding at a receiver;
and
inverting components of the decoded video signal in the chrominance spectral band in the other alternate television frames which were not inverted at the transmitter to produce a chrominance-inverted video signal at the receiver.

1 more element

A method of transmitting an analog NTSC colour video signal via a digital signal transmission channel, comprising the steps of:

(a) converting the analog video signal to a digital video signal;
(b) filtering the digital video signal in a digital filter, comprising a comb filter having spectral null points at odd multiples of half the television line frequency, to separate components of the signal in the chrominance spectral band from components in the luminance spectral band;
(c) recombining the chrominance and luminance components with the chrominance components inverted in alternate television frames to produce an alternate-frame chrominance-inverted digital video signal;
(d) transmitting said alternate-frame chrominance-inverted digital video signal via said digital signal transmission channel using interframe difference coding at a transmitter and decoding at a receiver;
(e) at the receiver, repeating steps (b) and (c) on the received, decoded, digital video signal with the chrominance components in the other alternate television frames, which were not inverted at the transmitter, being inverted, to produce a chrominance-inverted digital video signal;
and
(f) converting the chrominance-inverted digital video signal to a chrominance-inverted analog video signal which is reproducible on an NTSC colour television receiver.

4 more elements

Dependencies are inferred from the claim text.

Digital television transmission using chrominance inversion

Life of this patent

Digital television transmission using chrominance inversion

Life of this patent

Abstract

Claims6