[opendtv] Re: DTV on VHF Lo
- From: dan.grimes@xxxxxxxx
- To: opendtv@xxxxxxxxxxxxx
- Date: Wed, 17 Jun 2009 08:48:28 -0700
Cliff:
It looks like you are quoting someone that has done testing in Las Vegas.
I would be interested in hearing more.
I've been trying to figure out why DTV RF Ch. 2 (KVBC NBC Ch3) is so
problematic at various points around the city. I didn't have a spectrum
analyzer with me at the time but I would try to tune RF ch. 3 (analog) in
to get the best picture with little to no ghosting. I figured if the
analog looked good, the DTV was sure to come in. That didn't work. The
DTV tuner would vacillate from strong reception to week reception (based
on the internal meter) but never get stable enough to make a picture.
However, the internal meter reacted very slowly to changes so it was
impossible to determine the period of transitions.
Also interestingly, one site in the middle of town had impulse noise in a
pattern in the RF ch. 3 analog picture. I could not find the source
direction but did come and go. Perhaps this interference is strong enough
at that site to prevent a lock. But I did not experience the same noise
at any other location.
When you say impulse Fourier energy, I assume this means a very wide band
of frequencies (broad spectral energy) present due to a source sending out
a strong near-instantaneous EM pulse? Would the Fourier transform happen
within the receiver, thus not be visible on the spectrum analyzer, or
would one see it on a spectrum analyzer, too?
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Date: Tue, 16 Jun 2009 21:17:16 -0400
From: Cliff Benham <flyback1@xxxxxxxxxxx>
Subject: [opendtv] DTV on VHF Lo
"I can't speak for DTV on VHF-Lo although we made measurements in Las
Vegas on Ch 2 some years back and found pockets where a strong carrier
existed but atmospherics and impulse Fourier energy caused useless
demodulation."
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