Digital TV reception
Tue Aug 6 09:50:25 EDT 2013
<<On Mon, 5 Aug 2013 12:41:23 -0400, "M. Casey" <firstname.lastname@example.org> 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.
You also have to remember that the FCC assumes (and has always
assumed) that TV viewers will have an outdoor antenna 30 feet above
ground. Households with only indoor antennas are just SOL as far as
the Commission is concerned.
> truth. Owing mostly to the additional sub-channels, most urban viewers are
> able to recieve more channels than they had with analog, and with a far
> better picture quality than standard cable or satellite.
You're presuming that there is programming that people would want to
watch on those channels, which for the most part is not the case for
anyone under 50. All of the worthwhile scripted television is on
cable or VOD these days, or so say the people I know who are actually
interested in that kind of thing; the only thing keeping broadcast
alive for the under-40s is sports. (Many would say the same thing of
cable -- all they want is HBO Go and Netflix.)
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