What happened to I/Q?

[Pete Deksnis]

Quadrature modulation of course is a technique that allowed two chroma signals to be stuffed into the existing black and white television channel.

The word was that Philco got really ticked about RCA's declarations of parenthood for the fledgling NTSC color system. It was Philco who first implemented quadrature modulation for the developing compatible color specifications. They did it in 1951.

Not everyone used IQ demodulation in 1954. The CT-100 and the CBS-Columbia Model 205 did. The Westinghouse H840CK15 did not. By late 1954, when RCA brought out the 21-CK-55 (CTC2B chassis), their designers had dropped I-Q demodulation for an unusual Q/R-Y axis demodulation.

Years later, Donald Fink, an early video engineer, was reported to have said that the reasons for accepting I/Q demodulation by the second NTSC did not withstand the test of time.

There is no doubt that $$$$$, as Reeferman suggested, was the incentive for dropping I/Q demodulation in the CTC4. But an intriguing question for me is whether there was also a legal force behind the dumping of I/Q so quickly in the CTC2B.

http://home.att.net/~pldexnis/potpou...12-5-1950.html