How far is it to the cliff?
If you read the comments hidden at the bottom of each post, you may already know reader Gene Falk and I have been exchanging comments on the magic circle of coverage TV stations “should” be reaching. He’s found the formulas to calculate the distance between a transmitting antenna, and a receiving antenna. Basically, how far is the horizon?
Television signals travel according to the laws of physics. In a straight line, from point A to point B. But the Earth’s magnetic field, houses and buildings, trees, pollen and dirt in the air all affect the signals. Basically, when common sense says this is possible, it proves to be impossible. Like I said in a previous post, some people are having no trouble picking up DTV at great distances, while others are having trouble within sight of the towers.
The thing Gene is trying to grasp is what does these pretty maps the FCC publishes have to do with real life. I admit, at times, nothing. Keep in mind the FCC is run by lawyers and politicians. But they have some great software. They have some pretty maps that show coverage of analog at 5 Million Watts versus DTV at 200 Thousand Watts. In other words, according to the software, is exactly the same plus or minus a few percent.
Even with the pretty maps generated by software, I have always wondered exactly where is the real digital cliff. That absolute ledge where the signals can’t be decoded anymore.
The digital signal is indeed amazing in the fact we’ll use less power to reach the same area, just like your cell phone no longer needs to be in a suitcase to work reliably. There are “catch 22″ issues with digital. It takes a much better antenna at home. It does not like interior walls and reflecting surfaces. It seems to fall apart in rain and heavy humidity. I’m hearing even wind causes issues. The FCC responds with terms like “area of probability”- that a specific location will receive the signal most of the time, but less than 100% of the time. Nice to have a name for it, but a pain if you live in an area that does not have 100% coverage.
Gene disagrees with me on whether elevation has much to do with being more likely or less likely to receive digital signals. I can tell you that Raleigh is between the flat lands of the coast, and the mountains to the west. Our signal travels east much farther than it travels west. My Mom is 110 miles from Raleigh near a small town named Askewville, and I can pick up my current channel 55 DTV signal 90% of the time at her house. One of my buddies in Greenville, NC tells me he gets it 100% of the time on an indoor antenna. Another buddy in Asheboro can get the analog fine, but is having trouble getting digital at all.
I want you all to know the most likely area to have trouble is in the west and northwest area of the pretty perfect circle the FCC maps show mainly due to height above sea level and hills. Moore County, and Chatham County are areas with spotty reception. Up at the Virginia border folks will have significant problems with antennas around the lakes. The elevation of the land plays an important part of the distance a signal can be captured by the antenna. Out past the 60 mile zone, the higher the antenna the better. Folks to our east will have little trouble picking up our signal, but folks to the west in the higher elevation and hilly counties, will have spotty results.
The folks closer in are having big issues with DTV. Mainly due to the fact indoor antennas are the main type of antenna used. The majority of users with indoor antennas are not happy. Some are living with it “until the conversion in June” and have not even attempted to get a better signal. They believe it will be different after the analogs are shut off.
Wrong! Not necessarily, but possibly.
Different, you betcha! But certainly not solving every problem you have had. You may have the exact same issues after June 12th you are having now. If you are having issues now, there’s a significant chance you’ll have issues after 6-12. Resolve all issues now, and you’ll be fine after 6-12. Right now, to misquote my GM speaking about another topic, “it’s as bad as it will ever be”.
I’m taking my signal truck out this week in search of the digital cliff, and to see what is happening in certain areas. Monday I will head East toward Rocky Mount. Tuesday I hope to be back in Chatham/Orange County. If you want me to check in your neighborhood, drop me an email or post a comment and as time permits, I can snoop in the air to see how the signals are behaving. The digital cliff seems to be as elusive as the pot of gold at the end of a rainbow and varies according to the type antenna in use and terrain. We know it’s out there, but exactly where it is would be good information to have.
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Will we see any of this in NC?
DTV Cliff Effect Assistance Act Introduced In Senate
Would allocate $125 million to help pay for digital repeaters or translator towers
By John Eggerton — Broadcasting & Cable, 5/5/2009 5:00:00 AM MT
Maine Republican Senators Olympia Snowe and Susan Collins have introduced a bill to help broadcasters pay for translators to fill in digital signal gaps caused by the “cliff effect.”
The aptly-named DTV Cliff Effect Assistance Act would allocate $125 million to help pay for digital repeaters or translator towers to fill in areas where a weak signal means no signal at all (the cliff effect).
The money would be available through 2012 from a newly created Digital Television Transition and Public Safety Fund.
The bill would also require that those translators serve double duty to help out with the rollout of broadband service, saying that the equipment “shall reasonably facilitate the collocation of any wireless communications or broadband equipment,” with the stipulation that the requirement would not apply if there is “clear evidence” that co-location would create interference issues.
“I have talked to many people in Maine who have purchased a converter box yet they still cannot receive a digital signal or they are experiencing a drastic decrease in service. This is simply unacceptable,” said Collins in announcing the bill. “Unlike analog signals, digital signals are more susceptible to interference from mountains, hills, and tall buildings. Our legislation would provide funding to help increase signal strength by purchasing digital translators. Without action, too many Americans will be left with dark televisions once we fully transition to digital television broadcasting.”
The FCC has given broadcasters temporary authority to use translators to fill in gaps within their markets, but it has yet to finalize a proposal that would allow stations to use translators to reach viewers outside their markets who have historically received the signals.
In either case, without government help it will be an added expense for broadcasters struggling, with the rest of the country, through tough economic times.
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Hi Russ,
I don’t think we disagree very much.
My comment on the height of the tower base
was intended to point out that if the base
of the tower is 400′ up from sea level, and
the antenna heights above ground are still
2000′ up on the tower and the same at home,
I feel the added 400′ above sea level is
is likely to be shared by those viewers on
relatively flat ground (and the ground at
“the horizon”); the 400′ won’t add very
significantly to the Earth’s radius and the
broadcast-area portion of the world’s
surface would not be noticeably flatter
so the calculated theoretical “cliff”
distance would be about the same.
Of course, once you hit hills and valleys,
the situation has to be a mess.
The real surprise is that, according to the
graph I found, the “cliff” should be a lot
“closer in” than viewers are experiencing.
I am quite curious what is helping those
successful viewers who are farthest out.
As you have been pointing out, the reality
seems to be quite a strange mix of results.
We certainly don’t disagree on that!
Regards,
Gene Falck