Hello all,
I have a question about composite (CVBS) video and analog broadcast TV in
NTSC land.  Going from a composite video source to an RF input on a TV
usualy would be done with a "modulator'  but the real question is,  does the
'modulator' actually modulate anything, given that for NTSC you are going to
have to Amplitude modulate the luma,  frequency modulate the audio, and use
QAM for the chroma signals, I would expect that the commercial 'modulators'
wouldn't be doing this, for how cheap they are.   Is the composite signal in
actuality just upmixed with a local oscillator, filtered to the standard
bandwidths and sent down the coax, for the reverse to be done in the TV
tuner? All the online articles I see (mainly googling/wikipedia) are vague,
or I'm missing, the relationship between composite and broadcast RF
signals.  I have seen some people make "DIY video modulators"  and one took
a transmitter, lopped off half the PCB and fed the composite in and changed
a few components.  He didn't have a schematic, but It would seem to me, the
latter half of a transmitter would be upmixing, filtering and amplifying.

Thanks,
Jonathan Hallameyer
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