Quadrature amplitude modulation preserving one channel zero cros

Details Quadrature amplitude modulation preserving one channel zero cros Quadrature amplitude modulation preserving one channel zero cros

1988-06-28

1990-05-15

Shepperd, John W.

Facsimile and static presentation processing

Static presentation processing

Attribute control

358 15, H04N 1112

Patent

active

049262459

ABSTRACT:
The present invention provides a QAM modulation scheme compatible with a single channel demodulator. The inphase (I) channel is provided with luminance information encoded on a series of sine wave symbols. The quadrature (Q) channel is used for color difference values with a sine or cosine symbol being used for each color difference value. Alternate ones of these color difference symbols are inverted so that, on the average, their effect on the I channel zero-crossings simply cancels out. Thus, when sent to a single channel demodulator which expects a black and white picture, the quadrature channel will be filtered out; leaving luminance information which will be decoded as a black and white picture. The color information does not disturb the zero crossings of the luminance signal on an averaged basis, allowing the carrier recovery phase lock loop to maintain synchronization for demodulation purposes. When received by a QAM demodulator, the color difference values are recovered on the Q channel, to give a color picture. In one embodiment, the cosine symbols on the channel are offset with a positive or negative DC value, depending on whether the symbol is inverted, to shift the Q channel zero-crossings so they are aligned with the I channel zero-crossings.

REFERENCES:
patent: 3813483 (1974-05-01), Kurosawa et al.
patent: 4335393 (1982-06-01), Pearson
patent: 4675721 (1987-06-01), Dirr

Affiliated with

Also associated with

Rating

Quadrature amplitude modulation preserving one channel zero cros does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Quadrature amplitude modulation preserving one channel zero cros, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Quadrature amplitude modulation preserving one channel zero cros will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-625408