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How wide does line of sight need to be?

2547 Views 35 Replies 18 Participants Last post by  harsh
I'm moving into a new home shortly, and there are very tall pine trees on either side of the front yard in the general line of sight direction. So, there is a bit of a "window" in between the two trees. My question is, how big of a "window" is needed in order to pick up all the sats?
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lifelong said:
I'm moving into a new home shortly, and there are very tall pine trees on either side of the front yard in the general line of sight direction. So, there is a bit of a "window" in between the two trees. My question is, how big of a "window" is needed in order to pick up all the sats?
abt 20 degrees or so. you can use Dishpointer.com to check your address
you only need about 4 degrees for the Atlanta area, 99 to 103, as you now don't need 110 and 119 unless you want international programming.
tkrandall said:
you only need about 4 degrees for the Atlanta area, 99 to 103, as you now don't need 110 and 119 unless you want international programming.
Thanks for the info. Can you tell me how to figure how wide 4 degrees equates to at a rough distance of 30-50 feet away?
angle (in radians) times radius = arc length, which should be close enough here

4 degrees = .0698 radians x 40 feet = < 3 feet.

pretty narrow.

I should note you may get grief from the installer if he cannot see 119west to fine tune the tilt of the Slimline 5 dish, per his procedures. The Slimeline 3 dish which is just now coming out in some markets will elminate that, as it only sees 99, 101 , and 103.
tkrandall said:
angle (in radians) times radius = arc length, which should be close enough here

4 degrees = .0698 radians x 40 feet = < 3 feet.

pretty narrow.

I should note you may get grief from the installer if he cannot see 119west to fine tune the tilt of the Slimline 5 dish, per his procedures. The Slimeline 3 dish which is just now coming out in some markets will elminate that, as it only sees 99, 101 , and 103.
wow that is pretty narrow. now I realize the (one of many) downsides of being an english major. thanks for the math lesson.
tkrandall said:
angle (in radians) times radius = arc length, which should be close enough here

4 degrees = .0698 radians x 40 feet = < 3 feet.

pretty narrow.

I should note you may get grief from the installer if he cannot see 119west to fine tune the tilt of the Slimline 5 dish, per his procedures. The Slimeline 3 dish which is just now coming out in some markets will elminate that, as it only sees 99, 101 , and 103.
that assumes that locals in SD are on 101
curt8403 said:
that assumes that locals in SD are on 101
In Atlanta they are
The 4 degree angle is measured from the center of the earth. From the earth's surface it will be slightly larger (dishpointer.com will give the exact angles for each satellite). You should probably allow for a bit more (branches moving in the wind and future growth).
bobnielsen said:
The 4 degree angle is measured from the center of the earth. From the earth's surface it will be slightly larger (dishpointer.com will give the exact angles for each satellite). You should probably allow for a bit more (branches moving in the wind and future growth).
I would allow for a chainsaw as well. I know a lot of people who take a chainsaw to a Line of Sight problem
Keep in mind that if you're not in a Slimline3 test area (does anyone know where those are?) you will need to have the full 22 degrees available. NO installer will do a 5 LNB install without line of sight to 119.
bobnielsen said:
The 4 degree angle is measured from the center of the earth. From the earth's surface it will be slightly larger (dishpointer.com will give the exact angles for each satellite). You should probably allow for a bit more (branches moving in the wind and future growth).
The tree trunks are about 50-60 feet apart. Branches extending from each tree probably leaves a (totally eyeballed) window of about 20-30 feet, probably more as you go up towards the top of trees. It seems like enough, just a matter of getting the installer to hit the middle of the window. That's a completely different challenge.
curt8403 said:
I would allow for a chainsaw as well. I know a lot of people who take a chainsaw to a Line of Sight problem
It'd be nice, but in Atlanta we have a pretty tough tree ordinance for trees over a certain diameter. It's easier to get away with punching a man in the face than it is to touch a large tree with a chainsaw. I imagine trimming is no problem, but cutting one down requires an act of congress.
lifelong said:
It'd be nice, but in Atlanta we have a pretty tough tree ordinance for trees over a certain diameter.
u ever see heather tesch or sharon resultan in like the mall or supermarket ? :p
lifelong said:
It'd be nice, but in Atlanta we have a pretty tough tree ordinance for trees over a certain diameter. It's easier to get away with punching a man in the face than it is to touch a large tree with a chainsaw. I imagine trimming is no problem, but cutting one down requires an act of congress.
"Now there's No More Oak Oppression, for they passed a noble Law, and the trees are all kept equal now, with hatchet, Axe and Saw."
bobnielsen said:
The 4 degree angle is measured from the center of the earth. From the earth's surface it will be slightly larger (dishpointer.com will give the exact angles for each satellite). You should probably allow for a bit more (branches moving in the wind and future growth).
He is correct. Plus there is the effect of latitude on true look angle, but I have no idea how to calculate that one.

Check out this web site, just for kicks.... http://gjullien.fr/satellite.htm
Seems like 99, 101 and 103 would line up pretty well without using 119 if you did it yourself. Installers probably won't improvise from their procedures.
I didn't see it mentioned so... Are you trying to get HD channels or only SD, which will only need the 3LNB dish (4 degree LOS).
In the Atlanta market, unless you want international programming, as of July 31 there is no longer a need for 110w or 119w to get all the programming offered.
curt8403 said:
I would allow for a chainsaw as well. I know a lot of people who take a chainsaw to a Line of Sight problem
Here in the south, we call that 'midnight tree surgery'. :p
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