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April 1991


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82 Malcolm Dean 213-5-5676 <[log in to unmask]>
Reply To:
Film and TV Studies Discussion List <[log in to unmask]>
Thu, 18 Apr 91 15:34:00 PDT
text/plain (21 lines)
> > Due to the immense bandwidth required to transmit as much
> > information as a frame of high-resolution film can store, it is
> > unlikely that future systems will immitate film. They may,
> > however, be more akin to FM radio, which transmits NOT a signal,
> > but the DIFFERENCE in the source from moment to moment.
> This is wrong.  FM does transmit a signal directly, rather than
> any difference.  Both FM and AM radio modulate a carrier to transmit
> their signal, an AM transmitter changes the amplitude of the carrier
> in proportion to the input signal, an FM transmitter changes the
> frequency of the carrier in proportion to the input signal.
This is not a forum in radio theory, but your explanation
confirms what I said, which is that FM transmits a change in
frequency reflecting the difference in the source from moment to
moment. The important point is the concept of relative, versus
absolute transmissions.  In current video, the entire image is
refreshed in bands and frames. In film, the entire image is
presented in one frame. But in a relative transmission, pixels
which do not change would remain constant.