[opendtv] Re: Fixing VHF DTV Reception Problems
- From: "Dale Kelly" <dalekelly@xxxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Fri, 19 Jun 2009 17:44:12 -0700
> Is it not sensible instead to say, let's start with 12 dB as an initial
estimate, and then give ourselves some more margin to allow for the
DIGITAL CLIFF effect?
> Wasn't all of this totally predictable?
YES!
Dale
-----Original Message-----
From: opendtv-bounce@xxxxxxxxxxxxx
[mailto:opendtv-bounce@xxxxxxxxxxxxx]On Behalf Of Manfredi, Albert E
Sent: Friday, June 19, 2009 3:11 PM
To: opendtv@xxxxxxxxxxxxx
Subject: [opendtv] Re: Fixing VHF DTV Reception Problems
Tom Barry wrote:
> Well, I guess either they expected to get the same reception using
> 1/32 the power or they did not expect it. If they did not, and did
> not complain, then I guess they had some other reason to think it was
> acceptable.
But that's exactly why I asked "what were they thinking?" It's not like
this was the big unknown.
A/54, Section 8.5, makes this rosy prediction:
"For the same approximate coverage as an analog transmitter (at the same
frequency), the average power of the DTV signal is on the order of 12 dB
less than the analog peak sync power (when operating on the same
frequency)."
Hey, someone must have read A/54? Either at the FCC or at the affected
broadcast stations?
So, let's even ignore the fact that "lost coverage" when talking about
DTV means a dark screen. Did they do the numbers? If they claim that
WBAL at 5 KW gets roughly the same coverage as it did in analog, they
are saying that equality is reached with a drop of 18 dB. So, who told
them that this was acceptable?
If WJZ had been planning to use 9.8 KW, that is a drop in power of 15
dB. Who told them that would be acceptable?
Is it not sendible instead to say, let's start with 12 dB as an initial
estimate, and then give ourselves some more margin to allow for the
DIGITAL CLIFF effect?
Wasn't all of this totally predictable?
Bert
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