DirecTV and Line of sight?

Discussion in 'Archived Threads 2001-2004' started by Dougjef, Mar 29, 2001.

  1. Dougjef

    Dougjef Auditioning

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    I'm thinking of getting DirecTV and on their site they mention you must have a clear line of sight to the south. However I've read in a FAQ that that is not necessarily the case. I do have line of sight EXCEPT for about 10 pine trees that are blocking my view. YOu can see through them so they are not very dense. They are about 100 feet away from where the dish would be mounted. Will I be able to receive channels OK since the trees are somewhat close and not real dense? Thanks!
     
  2. Eric-S

    Eric-S Stunt Coordinator

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    Also remember that the small dishes have an offset LNB. This means that the signal bounces off the dish to the LNB at an angle instead of straight on. What this means is that the line of sight to the satellite is higher than it might seem. I'd give it a try and see how you do.
    However, if there are trees in the way, it probably won't work.
    Eric
     
  3. stephen abbot

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    Doug, you need to ensure that the elevation angle from your site to the satellite will clear the trees. The following page allows you to enter your zip code and it will tell you the azimuth and elevation for your address.
    http://www.directv.com/yoursystem/yo...082,90,00.html
    The elevation angle given will be the real angle that the beam will approach your site, in your case around 31deg. People refer to the fact that the satellite is higher than what you think, infact what they mean is that the arm of the dish will be around 20 deg below the elevation angle, ie the beam approaches the antenna higher than the LNB arm by around 20deg (most of these dishes have a 22.5deg offset). Thus in your case the LNB arm will have an angle around 10deg above horizontal with the beam entering the dish around 30deg above horizontal.
    As long as the top of the trees are below 31deg from your site then you should be fine. From simple geometry, 100ft from you 30deg is 57ft high, if the dish is to be mounted on the side of the house or roof then add that height as well, if that were say 12ft then the trees must be shorter that 69ft to clear.
    Hope this helps, I have assumed you are in Seattle with a Zip code of 98XXX
    Cheers
    Stephen
     
  4. Wendell R. Breland

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    Real Name:
    Wendell R. Breland
    Doug,
    Below is the info needed for a site survey. On the day and times listed the sun will be in the position listed, just see if you have a clear shot at the sun and estimate the angle offset. Conversely, there should be no shadows in the area you plan to place the dish.
    Seattle, WA (city)
    Population (1990): 516259
    Location: 47.62180 N, 122.35032 W
    Your longitude in degrees:122.4
    Your latitude in degrees:47.6
    Time Zone: Pacific
    Azimuth of Satellite: 152.0°
    Elevation of Satellite: 31.5°
    Saturday, March 31, 2001
    Sun is 12.1° above sat position at 10:54am PST.
    Saturday, April 7, 2001
    Sun is 14.9° above sat position at 11:56am PDT.
    Saturday, April 14, 2001
    Sun is 17.6° above sat position at 11:57am PDT.
    Saturday, April 21, 2001
    Sun is 20.2° above sat position at 11:59am PDT.
    Saturday, April 28, 2001
    Sun is 22.6° above sat position at 12:01pm PDT.
    ------------------
    Wendell
    Technical Services Supervisor
    MAETV
     
  5. Dougjef

    Dougjef Auditioning

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    WOW. Great information Wendell and Stephen. I'm actually not in Seattle but a suburb with a zip of 98006. Will those #'s change much Wendell? Also I figure the azimuth you can calculate with a compass but what about elevation? I could estimate it with the sun readings you provided..is there a better way? It's probably something very easy..been a while since I've taken geometry...ha. Thanks again.
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  6. Tomas_S

    Tomas_S Agent

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    I installed my dish myself. I didn't think I could do it because I had a bunch of pine trees in front of me too. After a couple of days, i was able to get 90% signal strength.
    Keep in mind what Eric-S said, the angle at which your pointing is higher than the LNB pointing straight.
    If you are installing it your self, the key is patience! take your time setting it up and make sure the pole is plumb!
    Tomas
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    Tomas (t [​IMG]' m [​IMG] s)
     
  7. John_Bonner

    John_Bonner Supporting Actor

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    I also installed my dish and had similar tree problems. Doug, one important thing to note: you said now you can see through the trees but how about in a month or two? Line of sight improves in the fall and winter when there is less foliage.
    Here's a tip I got from a dish installer: Take a protractor (the semi-circle with the degree markings) and tape a straw over the proper angle (for you 31.5). Now go to where you plan on mounting the dish. Look through the straw. If you have a clear view (ie. no trees or other obstructions, you've found a good spot to mount).
    I thought I could mount my dish on the side of my house because I could see "through" the tree in the backround but I couldn't get squat. I had to mount on the roof to clear the trees. Hope this helps.
    JB
     

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