Digital TV reception

[M. Casey]

In a real world environment, and with the differences in the mode of 
transmission and the differences in power rating methods between analog and 
digital and the quality of today's available receivers taken into account, 
digital using about 50% of analog power would be closer to equal in most 
cases. And even 50% might not be enough in the rough terrain of 
Central/Western Massachusetts and Northern New England, and many other areas 
of the country.

From: "Garrett Wollman" <wollman@bimajority.org>


<<On Mon, 5 Aug 2013 12:41:23 -0400, "M. Casey" <map@mapinternet.com> said:

> near the transmitter. The BIG problem is that the stations' power limits
> were cut down so far that many suburban, rural, and even urban areas 
> cannot
> get a reliable signal.

To some small extent that's true, but you have to compare apples to
apples.  Analog TV has a high peak-to-average power ratio (about 5:1);
digital TV has a very low peak-to-average ratio (nearly 1:1).  Analog
TV was regulated on peak power (which occurred only during sync
pulses), whereas digital TV is average.  So it's entirely rational to
expect that 20 kW ATSC on VHF will be the equivalent of 100 kW of
NTSC-M, but there's also processing gain in the receiver (although
it's only about 3 dB as I recall).  The limits as originally set were
probably a bit low, but you shouldn't ever need 1 MW of ATSC on UHF to
replicate your 5 MW NTSC-M service on the same channel.