On Jun 8, 11:38 am, "Bob Myers" wrote:
"Radium" wrote in message

ups.com...

Hi:

Video signals for NTSC, PAL, and SECAM television are transmitted on
AM carriers.

No, they're not. And there's no such thing as an "AM carrier"
or "FM carrier" to begin with. The carriers themselves are simply
signals at a given frequency. "AM" or "FM" refers to the modulation
IMPOSED on those carriers - in other words, how the information
to be carried is used to modify some aspect of the carrier signal.

Okay. Thanks for clearing this up.

In TV, most systems employ a version of AM to carry the luminance
(Y) signal; the color (chroma) information is carried via a somwhat
different version of AM, and the audio is most commonly FM.
The French SECAM system as originally implemented carried the
chroma information on TWO frequency-modulated subcarriers.

Why not carry the luminance-signal on FM and the audio-signal on AM?

I'd really like buy a TV with a FM-video receiver; I want to find out
what FM-video disturbances in the SHF [Super High Frequency ]
frequency-range look like. I am sick n' tired of AM video.

AM should be used for analog audio. FM should be used for digital
video.

Nonsense. The choices of AM and FM within the original analog
standard definitions were made for some very, very good reasons.
Digital television is a completely different beast, and is presently
broadcast using two very different modulation schemes - the
U.S. standard (ATSC) using 8-VSB, while the rest of the world
(mostly) will be using COFDM under the DVB-T standard.

Couldn't FSK [the digital equivalent of FM] be used for luminance [Y]
signal of the digital video?