FM Video -- Compression and "backbone"

Bob Eld wrote in

Simple answer: FM is wasteful of bandwidth with other things equal. The
> video signal needs about 3-1/2Mhz of bandwidh. It would be difficult to get
> this with FM unless the channel spacing was maybe 10 to 20MHz depending on
> modulation index.

What if the WMV [Windows Media Video] digital compression is used and the color resolution is decrease sufficiently? Its possible to have a supreme quality in terms of number of pixels and frame rate. All you have to do is compress the WMV's color resolution and you can get a bit-rate that is low enough not to hog bandwidth.

Also note that digital modulation is also AM where the phase also carries
> information. There are many modulation schemes such as QAM, etc. but they
> all use AM as the backbone.

Does this mean PCM is also AM at heart? Analog signal is converted to PAM [pulsatile version of AM]. This PAM is then converted to PCM

Is it possible for digital modulation to use FM as a backbone? Has this ever been done?

What about converting to analog signal to PFM and then PCM [or the "FM equivalent" of PCM]? Has this been done before?

What is the "FM equivalent of PCM"? [as you say, PCM uses AM as a "backbone"]

Thanks,

Radium

Chris Welsh try looking up Frequency Shift Keying (FSK)

AFAIK, Frequency-Shift-Keying is used in 1-bit only. One represent a certain frequency, zero represents another frequency. What if I want

The

to get

depending on

carries

they

this

Read up some more of FSK, also read up on PSK especially O-QPSK. Here are some links you may find interesting.