W. MA doesn't get Boston TV channels anymore
Wed Sep 1 18:08:04 EDT 2010
Can't speak to the 8-vsb debate but agree with the 2nd part
of Sid's statement.
<<On Tue, 31 Aug 2010 07:35:05 -0400, Sid Schweiger <firstname.lastname@example.org> said:
> From what I've seen and read, it's a combination of 8-VSB and the
> substantially lower-than-analog ERP allowed for digital stations.
Apples and oranges. Digital TV is regulated for average ERP; analog
TV is regulated for peak ERP (which occurs during sync pulses). The
peak-to-average ratio of "System M" analog TV is about 5:1 as I
understand it, which is why they chose 1000 kW as the average-power
limit for UHF DTV (versus 5000 kW peak for NTSC-M). However, that's
not enough to account for the horrendous disadvantage the Commission
gave the VHF-low band, which I suspect reflects a failure to properly
account for the noise floor in that band, particularly when it comes
to impulse noise.
As far as allowed power is concerned
Less apples & oranges = less fruit (less signal)
I haven't seen any Boston TV here in Western Mass.
since the digital conversion last year. And I don't expect to see
any at my location 64.2 miles from the WBZ-TV plant.
>From the previous discussion on this remailer, last year, and from
opinions of various engineers, and FCC engineers, the ratio of peak
NTSC vs. average ATSC could be anywhere from 1.5:1 up to 20:1.
>From the real world it appears to be closer to 2:1-3:1. The best
example is WFSB, Hartford's 1 million watt digital signal on
Channel 33. It's close, but just not as robust as their old 100,000
watt signal on Channel 3. If it were 2 miilion, maybe.
Springfield's Channel 22 was about 3 million watts
analog, then moved to Ch. 11 for digital with 15,000 watts. It's no
where near it's old self. Maybe 100+kw would equal the old
(And, not all ERP's are created equal.)
Digital doesn't make it as well as analog with the FCC allowing
UHF only 20% (5:1) and VHF only 5% (20:1).
The whole FCC plan for TV power has been flawed since its'
beginning. If set up in any scientific manner the allotment would be on a
sliding scale by channel. I understand why they set it up that way in
1940 or 1950, but ya think they could have figured out it wasn't
right and corrected it by 2009?
Even with the correction for higher frequency, and thus less bending
of waves to cover distance, given equal facilities otherwise,
there's no way a 316 kw station on Ch 13
(210-216 MHz) would equal the coverage
of a 5000kw station on Ch 14 (470-476 MHz). With the digital
conversion, It got even worse.
Even with better building penetration on the high UHF channels,
but with current FCC power rules, if they think that there is a significant
"antenna tv" audience, most broadcasters
would want to be on the low UHF channels. My guess is that the
Channel 7/42 experience will look like an aberration a few years
from now. If, or maybe when, VHF is allowed to increase to
say, 30 or 40% of analog power, then some may want to go there.
Looks like it may be going that way,too.
Today, a Las Vegas digital Ch. 2 is licensed for 27.7kw (27.7%),
another has a CP request for 105kw on Ch. 11 (29.7%), and at least
3 Los Angeles stations have CP requests for 115-120kw on Ch.'s 7-13.
Those figures are heading toward a more realistic 3:1, or 2:1 mark.
Since many TV's were short spaced for digital, I doubt we will
see the UHF 1 million watt limit upped. And, for market coverage,
few UHF's ever increased power to the 5M limit, but almost all
VHF's were at the 100kw & 316kw limits.
Many digital UHF's are stuck at a power far below the present limit.
A good example of that is Channel 30 in Hartford.
I doubt the noise floor is a significant signal blocking issue.
Of course, extraneous man-made & occasional high bursts of natural
noise is an issue at all TV frequencies on one occasion or another,
but are usually confined to more isolated cases than the complaining
would make it seem.
K1MAP, in Western Mass.
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