[old_tv_nut]

So Wayne, what I gather is that RCA did later attempt to improve chroma resolution by again using I /Q demodulation only to find that encoders were not limiting the Q bandwidth to 500kHz?

THE PROBLEM IS/WAS THAT THE NTSC SPEC SPECIFIED ONE ROLL-OFF FREQUENCY 3 DB DOWN, WHEN A SPECIFICATION OF A TRAP ON THE LOWER SIDEBAND CORRESPONDING TO THE UPPER SIDE SOUND TRAP WOULD HAVE BEEN MUCH MORE SPECIFIC.

I always wondered in the latter years of NTSC composite encoding whether the true NTSC specifications for 1MHz I and 500kHz Q were still used. Or because the assumption that pretty well all receivers used equiband narrow band (500kHz) chroma demodulation.
I THINK CAMERA ENCODERS CONTINUED TO USE I/Q NEARLY TO THE END, BUT OTHER GEAR, NOT SURE.

Your reply concluding that the RCA re introduction of I / Q demodulation revealed too much Q component above 500kHz suggests to me that chroma encoding by the 1990s had abandoned I / Q and simply used slightly wider band R-Y / B-Y. MAYBE, BUT NOT SURE. IT WOULD HAVE REQUIRED SURVEYING STUDIOS TO SEE WHAT GEAR THEY HAD AND ITS INTERNAL DESIGN.

To my earlier question on the visual effects of quadrature crosstalk on transients: how obvious and ojectionable was the crosstalk in the picture? I see no evidence of it on my CTC5 Deluxe which has the wider chroma bandwidth. Perhaps due to an abandonment of I /Q encoding, it is because the encoded signal no longer has an I component from 500kHz to 1MHz?
IT WAS OBVIOUS ON A 19 INCH TUBE. I THINK THAT THE FAILURE TO SPECIFY THE Q FILTER MORE TIGHTLY ORIGINALLY MAY HAVE HAD SOMETHING TO DO WITH DOING A LOT OF VIEWING ON SMALL SCREENS.