31-10-2017, 03:43 AM
Although it may be noted that Carnt and Townsend came out quite strongly in favour of positive modulation for NTSC colour systems. See Volume 1 page 429ff.
Apparently NTSC I chose negative modulation in 1941 mostly because it made for easier for receiver black level AGC circuits. But early on it was necessary to develop gated AGC systems because simple peak level systems had poor immunity to noise impulses. Noise-gated sync separators were another early development for the same reason.
Cheers,
Steve
Apparently NTSC I chose negative modulation in 1941 mostly because it made for easier for receiver black level AGC circuits. But early on it was necessary to develop gated AGC systems because simple peak level systems had poor immunity to noise impulses. Noise-gated sync separators were another early development for the same reason.
Cheers,
Steve
