[TowerTalk] HD Over-the-air TV

[darrel]

Today, almost all the DTV signals are at UHF and relatively low power
compared to the current AM/FM NTSC signals.  In a few years when they have to
give up their analog channels, many will move back to their VHF assignment
(though much less likely to 2 thru 6 than to 7 thru 13).
Here in Los Angeles, I can usually get most stations (25 miles away on Mt.
Wilson) with a small UHF Yagi or 4-bay bow tie.  Even when it's only SDTV
rather than HD, it's amazingly better (like DVD vs a tape).  Ultimately, they
can split the available 18 Mbits/second into as many as 16 subchannels
(though the most I've seen is 6, on the educational channel).  Good quality
HD needs about 75% of the bandwidth.  A good SD signal takes maybe 20%.  It
is possible to pick almost any bandwidth, but as it goes down, both detail
and the ability to follow action scenes suffers.  It also has surround sound
like DVDs.

As others have noted, it's nearly always all or nothing, like a dirty DVD it
will freeze or get very blocky but only in a very narrow range of signal
strength.
  Darrel AK6I


--- Lee Buller <k0wa at swbell.net> wrote:
>  
>   I know that this might be a little off topic, but I find the whole idea
>  ... DTV ...
>