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#1
Old 10-30-2010, 06:07 PM
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Join Date: Jul 2001
Location: Colorado Rockies.
Posts: 11,493
Educate me on direct line of site radio for internet.

Iím looking to get off my satellite system, and go terrestrial.
There is a new internet/phone tower about 3 miles from my house. I found out about it by a lot of Goggling. The nice fellow at SkyBeam even sent me a map of where it is.

What surprises me, is that this new tower is only 3 miles from my house It canít possibly have clear line of sight to more than perhaps (very, very optimistically) 500 homes (if they cut trees down) And what is odd, is that all of those folks already have Cable or DSL (I canít get either). All of those homes are within about 10 miles.

The question(s) are then. Line of sight radio. Perhaps this tower services communities 30-40-50 miles away? And it is also a repeater for other signals?

It canít be that tall, though I am sure it is on a ridge. In any case, it doesnít have any aviation beacons on it. I drive the pass every day and I have never seen it.

Can line of sight radio signals be picked up without line of sight if you are close to it? Parabolic antenna? From my house, there is not much more than trees in the way.

But lots of Ďem. Heavily treeded for about a mile, then looks pretty clear for 2 miles to the transmitter.

I guess there are certain frequencies that only work line of sight? Even when you are just 3 miles away? It's got to be one hell of a powerfull transmiter for them to set it up.

I can get a tech from the company to come up and test the signal strength at my house (SkyBeam), but the only way to do that is to sign up for a plan first. If it does not work, I get refunded all charges (makes me very hesitant though). But I would prefer to be a bit more educated about it first. I donít want to waste folks time, so I turn to the SDMB, and I hope this is not wasting your time.
#2
Old 10-30-2010, 10:21 PM
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Join Date: Aug 2010
Location: NY Metro area
Posts: 1,828
I don't know but it depends on a lot of factors including the broadcast frequency (some wavelengths penetrate intervening objects better than others) and signal strength (if the signal is strong enough, you'll probably be able to pick it up).

For example, I set up an HDTV antenna for a friend who lives about 50 miles (in a direct line) from NYC. We had to mount the small antenna (about 6"x8") on his back porch - which I'm pretty sure was not a direct line of sight to the transmitters. Even so, he's getting all of the major stations except ABC.

Honestly, 3 miles doesn't sound like a lot even for a fairly weak signal - unless you're talking about wireless routers or cordless phones. But even for a weak UHF/VHF broadcast frequency that shouldn't be a problem. Something up in the 2-5GHz range though, I don't know.
#3
Old 10-30-2010, 10:39 PM
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Location: Arlington, TX
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"Line of sight" in radio communications doesn't refer to ability to physically see the transmitter from the receiver. Radio signals, in general, care naught for trees, buildings, even small hills ... See this and this on Wikipedia for a brief introduction. For example, a 100' tower on the top of a 150' ridge (relative to local terrain) will provide LOS signals for about twenty miles around. Large hills or other tall ridges can cast a radio 'shadow', but very few other kinds of obstructions will matter.
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#4
Old 10-31-2010, 12:16 AM
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Join Date: Jul 2001
Location: Colorado Rockies.
Posts: 11,493
Thanks to both of you. And Iíll look at the links
EhhÖ I donno SCSimmons from your site/cite Ė
Quote:
Originally Posted by http://en.wikipedia.org/wiki/Line-of-sight_propagation
<snip>However, at higher frequencies and in lower levels of the atmosphere, neither of these effects apply. Thus any obstruction between the transmitting antenna and the receiving antenna will block the signal, just like the light that the eye may sense. Therefore, since the ability to visually see a transmitting antenna (disregarding the limitations of the eye's resolution) roughly corresponds to the ability to receive a radio signal from it,</snip>
I donít know if this transmits at high frequency or not.

Though the other link talks about higher frequencies bending slightly towards the earth. (I suppose that they are talking about hundreds or thousands of miles though).

The dern tower is only 3 miles away. Iíll pull out the maps and see if anything real is in the way. If it is directional, (can they be set up that way?) I might be too close to it. But on the other hand, I also suspect if it has ANY power at all, I canít miss it as I am so close.

The sales guy may know less about radio transmission than I do. But he really really made it sound like I had to a literal direct line of sight. See it through a telescope type line of site. If that is true, this is going to be a very, very bad system for the Colorado mountains. you would need one on every other tree.
#5
Old 10-31-2010, 10:34 PM
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Join Date: Nov 2001
Location: NH, Escaped from MA
Posts: 2,866
In my early career, I sold and installed wireless networking systems. Anything above 2Ghz will not penetrate tree cover well, if at all. Too many times, I had to tell a potential customer that I couldn't sell them a solution (which sales guys hate to do) because I didn't have line of sight.

In wireless networking, at distances more than "inside your house," it's very literally Line of sight. (Plus a little below the actual line for something called Fresnel zone clearance)

Now, if this is a real tower, you may be able to get up to your proposed antenna sight, and see if you can actually see the tower. This might give you a good indication as to whether you have line of sight or not. I used a similar service at a job I had a few years ago, to bring in a 2nd alternative Internet connection, which was independent of the copper wire in the street.
#6
Old 11-01-2010, 12:48 PM
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Location: Arlington, TX
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Quote:
Originally Posted by enipla View Post
If that is true, this is going to be a very, very bad system for the Colorado mountains. you would need one on every other tree.
Mountains always suck for wireless transmissions. I don't remember looking at Colorado, but at my last job, working for a wireless telecom provider, I do recall being entertained looking at the detailed coverage maps of our service in the Appalachians. It was remarkably ugly from a marketing point of view (probably why maps at that resolution were never, ever made available to customers); but from an aesthetic point of view, the patterns were actually very lovely. Sort of abstract artwork, with the swirls of partial and complete coverage blackouts following the ridges and valleys ...
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"You won't like me when I'm angry. Because I always back up my rage with facts and documented sources." -- The Credible Hulk
#7
Old 11-01-2010, 12:59 PM
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Join Date: Mar 1999
Location: I am Queens Boulevard
Posts: 14,142
My friends in a very rural area have line-of-sight. It definitely beats dial-up which is what they had before! But the major issue is, at least with their plan, you get a certain amount of data per month, and its pretty easy to go over. My friends' husband, for instance, doesn't play networked Xbox games, because it uses too much data. For everyday internet usage - browsing, shopping - it doesn't seem to be a big deal but if you want to stream movies or download music or play networked videogames, it seems to add up pretty fast. At least, they are always mentioning and paying attention to their data usage.
#8
Old 11-01-2010, 01:48 PM
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Join Date: Jul 2001
Location: Colorado Rockies.
Posts: 11,493
Thanks again everyone. Right now I have satellite, so I am very aware of download limitations.

The thing is, I would like to do a little bit of remote desktop to work, and my moms house. The problem is the latency. That, and they want to charge me another 30 bucks a month for a static IP. Pushes it up to $90 a month. For download speeds of about 700k...

Um, no.
#9
Old 11-01-2010, 02:11 PM
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Join Date: Sep 2003
Location: Las Cruces
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I had a line of sight system for about 5 years. I had phone service but no DSL, so I chose line of sight over cable (I have Directv).

In my case, the transmitter was 3 miles away but I literally had line of sight to it. In my case, it was 1.5 Mbps down, 256 Kbps up service, I usually had 1.0 - 1.1 Mbps down.

I don't know if it was the particular equipment my provider had, or the nature of the system, but I often had outages during rainstorms, and also had to have my receiver/antenna replaced once. During my last few months with it I had serious latency problems - latency up up to 30 seconds. That did it, I finally gave up on the system because DSL became available in my area at much faster speeds and for the time that I've had it (almost one year) - rock solid reliability.

When it works, it works great. When it didn't work, it really sucked. I'd guess it didn't work about 3-4% of the time, which doesn't seem like much, but it was.
#10
Old 11-01-2010, 02:17 PM
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Join Date: Aug 2005
Posts: 640
This won't help you now, but newer wireless networks like Verizon's LTE use signals in the same range as VHF TV stations, and so have much better range and speeds.
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