Re: Analog Cable Going

Guy wrote:
> There's no reason in the world that the cable companies must send a
digital 
> broadcast over the cable as a digital signal. Just as a converter box 
> converts a digital signal to analog and then sends it to your set over
the 
> coax connector, so too can a cable system do the conversion at their 
> headquarters and send it as an analog signal from there to your house.

  There are very good reasons to go all digital - bandwidth! Each analog
NTSC channel takes up 6 MHz of bandwidth. In that same frequency space,
they can insert a digital QAM-256 signal with a 38,4 Mbps data rate
which can carry 9 to 10 high quality digital SD channels or 2 full
bandwidth HD channels (or 3 over-compressed HD channels as Comcast has
started to do).

  Analog NTSC is a major bandwidth hog. The bandwidth crunch is between
your house and the head end. With 135 channels available in a typical
860 MHz system, a typical cable line-up of 70+ analog channels takes up
a huge chunk of the available bandwidth. By turning off 10 analog
channels and replacing them with digital QAM channels, the cable company
can add 90 SD 480i channels of better picture quality or 20 HD channels
with 5.1 sound. Analog NTSC has served us well, but its' time has passed.

  Alan F