[opendtv] Re: Which Modulation Would You Choose on a really bad day?
- From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Mon, 18 Sep 2006 20:32:24 -0400
negrjp wrote:
> How about quadrature modulation used in dNTSC? I think this
> method is better than 8VSB because Moviebeam uses this
> modulation system with indoor antenna.
Problem is, it requires about 40 dB of C/N to work. Not so hot. 8-VSB
should be able to do much better, and provide more bit rate, at the same
time.
I don't disagree at all with Frank Eory. It's possible all of this is
pointless jabbering. But it's still there, and it's fun to see what
happens if the rubber were finally allowed to meet the road, so to
speak. TURN OFF ANALOG. That's the only way to get things going, on way
or the other.
This past Saturday I achieved good success. I went to the upstairs TV,
the one with Radio Shack double bowtie and the Digital Stream HD3150
Plus, and tried to receive WETA-DT. I don't usually use the upstairs TV,
so I hadn't fiddled with it for some time.
To remind folks, WETA-DT, at either 75 or 90 KW ERP, is adjacent to
WETA-TV, at 2.29 MW ERP.
Note: to try a new channel, in this case virtual 26, actual 27, you
cannot tune to 26. You have to tune to the real channel. And even then,
it won't (with my STBs) be entered into the table of virtual vs actual
automatically just by being tuned in. But at least I noticed very solid
reception. Finally.
Perhaps because I am using an low gain antenna upstairs, the strong 26
analog was not causing the AGC to clamp down on the low power Ch 27.
Whatever the reason, WETA-DT came in solid in the upstairs set. In order
to receive its multicasts, though, I had to get WETA-DT entered properly
in the STB.
So I did one of those additional scans, i.e. scan the entire TV band
again, but only add new stations. The scan doesn't start from scratch.
Son of a gun, with this update scan, the upstairs set (with indoor
antenna) picked up four more multiplexes than before. Solid. Two were
local stations, but they have to travel through the house to get to the
back of the twin bowtie antenna. These first two were a Pax station,
four subchannels, and an independent MHz Networks, also 4 subchannels.
Both are atrocious in analog, full of ghost, and even drop sync in
analog. But "perfect" in digital.
It also added WETA-DT, PBS in DC, as I said, and WNUV-DT, which is a CW
network station in Baltimore (almost 50 miles as the crow flies).
So now, two solid Baltimore stations come in upstairs, WJZ-DT and
WNUV-DT.
So, bottom line, 10 solid DT stations (multiplexes) upstairs with indoor
antenna, 13 downstairs with outdoor antenna. Downstairs, I can't yet
include WETA-DT, since it is very spotty.
This is a 3rd generation box. We'll see over time how many of these turn
out to be flaky, but Saturday during the day, and late at night, no
change.
So again, is this better or worse than analog? For both sets, in terms
of what I would actually put up with, I'd say better than analog by some
margin. I don't get any 10 acceptable stations in analog, upstairs. But
I'm positive 8-VSB could be better.
Bert
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