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This is a discussion on TVFool Question within the DTV | HDTV Reception and Antenna Discussion forums, part of the Over-the-Air (Antenna TV) category.

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  1. #1
    DTVUSA Rookie
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    Default TVFool Question

    On TVFools FAQ, it lists

    1Edge: Single edge diffraction
    2Edge: Double edge diffraction

    but what's the real difference in layman's terms. I'm not very technical in HD reception.

  2. #2
    DTVUSA Member 1inxs's Avatar
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    Single edge is when the signal hits the first hill or mountain. A double edge is when it hits the second hill.
    Siting the antenna

  3. #3
    Contributor staticMHZ's Avatar
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    It means there is something between you and the transmitter that blocks LOS (line of sight). Most commonly a hill, a mountain, a building, tree, water tower, etc.

    In order to get better reception you have to get your antenna as high as you can, so nothing stands in the way.

  4. #4

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    That's a great explanation, and I thank you. I'm learning things here I never even thought about before. Who knew this somewhat frustrating would be so educational? <G>

  5. #5
    DTVUSA Member divxhacker's Avatar
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    I guess you might need to get someone to make this:

  6. #6
    Contributor staticMHZ's Avatar
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    This is one way you can look at it


  7. #7
    DTVUSA Member 1inxs's Avatar
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    Quote Originally Posted by staticMHZ View Post
    This is one way you can look at it
    Or you could just click on the link included in my post and view single edge or double edge diffraction with computer generated radio waves. The double edge occurs when radio waves hit hills, mountains or the radio waves coming from the first edge of diffraction. Your picture only depicts a single edge diffraction

  8. #8
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    Quote Originally Posted by staticMHZ View Post
    This is one way you can look at it
    I think this is the most awesome illustration of that concept I have ever seen.

    - Trip
    N4MJC

    Comments are my own and not that of the FCC (my employer) or anyone else.

    RabbitEars

    "Ignorance and prejudice and fear walk hand in hand..." - Rush "Witch Hunt"

  9. #9
    DTVUSA Member CptlA's Avatar
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    Quote Originally Posted by Trip View Post
    I think this is the most awesome illustration of that concept I have ever seen.

    - Trip
    LOL, there's something to be said about top notch Microsoft Paint skills.

    Quote Originally Posted by divxhacker View Post
    I guess you might need to get someone to make this:
    Div, what the heck is that????? Not your antenna right?
    Last edited by CptlA; 05-30-2009 at 04:20 PM.

  10. #10

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    I like the sketch and the photo, both. They each do a certain amount of illustrating what has been discussed. As for clicking on the link, that's so much work! lol

  11. #11
    DTVUSA Member 1inxs's Avatar
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    Quote Originally Posted by Orrymain View Post
    I like the sketch and the photo, both. They each do a certain amount of illustrating what has been discussed. As for clicking on the link, that's so much work! lol
    Hehehe, so true

  12. #12
    Super Moderator Piggie's Avatar
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    Quote Originally Posted by staticMHZ View Post
    This is one way you can look at it
    The on thing I would add is the guy throwing the remote at the TV, then pulling out large clumps of their hair. lol

    Great picture.
    Last edited by Piggie; 05-31-2009 at 08:24 AM.

  13. #13
    Super Moderator Piggie's Avatar
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    Quote Originally Posted by 1inxs View Post
    Single edge is when the signal hits the first hill or mountain. A double edge is when it hits the second hill.
    Siting the antenna
    If you look at these drawings on the page above close, what might not be apparent, is some times there are ways to get a good signal behind something blocking it.

    Cowboy already gave one good thing to try, tilt the antenna up as much as 15 degrees. I have read documented cases of this working in particular if you can see the top of the hill, mountain or building from the antenna. Then it's worth a shot to aim the antenna up toward the top of the hill.

    If you can't see what is blocking you can try the angle adjustments, but also try not only raising the antenna but lowering it. Some times going lower you either cancel one of the refracted waves from the edge (see images in link above) or sometimes you just find a spot where the interference add constructively giving a higher signal.

    So times as the pictures show move the mast to the other side of the house.

    What I like to try is get a 15 ft mast or so and don't mount it but have some help too. Move it around the yard to see if in all places you might mount the antenna if there is a difference in reception.

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