Re: How will the US local area stations commerate the end of System-M?

In alt.video.digital-tv Doug Smith W9WI <w9wi@[EMAIL PROTECTED]
> wrote:
| On Sat, 03 May 2008 17:16:40 -0500, Bruce Tomlin wrote:
| 
|> In article <fvg71302hp7@[EMAIL PROTECTED]
>, phil-news-nospam@[EMAIL PROTECTED]
 
|> wrote:
|> 
|>> OTOH, if you put 2 stations on _adjacent_ channels, with the same ERP,
then
|>> they should be fine transmitting from the same tower.
|> 
|> Except that from what I've seen, the maximum power UHF analog signal is

|> 5 megawatts, and the maximum power UHF digital signal is 1 megawatt. So

|> if the analog is over a megawatt, they _wouldn't_ have the same ERP.
| 
| Do note that analog and digital powers are measured differently.
| 
| Analog power is measured at the peak of the synchronizing pulse. 
Digital
| power is averaged over a period of time.
| 
| 1 megawatt of DTV power is more like 2-3 megawatts of analog. 
(depending
| on analog program material...)  

Adding to this:  what matters is the actual energy level of the sidebands
that
carry the information.  Analog TV wastes most of the energy on a carrier
and
the sidebands that carry the sync pulses (im****tant to get, but it is
overkill
in the energy amount).  Digital has a small pilot carrier and the rest is
virtually all sideband information.  Digital also has some amount of error
correction coding.

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