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Mast Myths?

Discussion in 'DIRECTV General Discussion' started by sstv, Oct 6, 2009.

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  1. joe diamond

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    Again,

    The plumb mast just makes it easier.
    With the return of the bigger dishes it has again become important to make sure the settings that are tuned at installation stay where they are put. This means monopoles, whatever it takes to get a firm attachment to existing soil or on a structure and checking things again after all work is finished. Conditions vary but the need for good tuning and a clear LOS are the constants.

    Joe
     
  2. Jan 4, 2010 #202 of 217
    cartrivision

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    I have supported and proved it with very simple statements of fact that you or anyone else have been unable to show to be false, but since that you seem to have missed those simple irrefutable statements, I'll repeat them again and invite you to refute them if you think you can......

    What we all are calling the the elevation and azimuth axes (from the perspective of your plumb pole) are differently oriented coordinate systems for every plumb pole at a each different location on earth, and furthermore, none of those different coordinate systems have a constant or "correct" relationship to the satellite arc. For the vast majority of plumb pole installations, adjusting the elevation setting on the dish mount moves the dish in a direction that is not perpendicular to the satellite arc.

    Everyone's elevation and azimuth adjustments move their dish in a direction that is not only skewed from other people's definition of elevation and azimuth, but is also differently skewed from the arc of the Clarke belt that the satellites reside on, and differently skewed from any other constant coordinate system in space.

    Every one of those differently oriented coordinate systems which all intersect the arc of satellites at different angles cannot possibly be moving along some theoretical "correct" two axes of adjustment, since every one of them has a different orientation with no fixed or constant relationship to the arc of the satellites (or any other constant reference point, line, or arc).

    Please refute any of the above statements if they are incorrect by stating exactly what is incorrect about them.

    Also, please explain what you think the "correct" orientation of the adjustment axis should be in relation to the arc that the satellites lie upon. Must the elevation adjustment on the dish mount move the dish perpendicular to that arc? If not, what it the "correct" direction of movement for the elevation adjustment in relation to that arc, and how does having a plumb pole assure that that "correct" direction of movement in relation to the arc of the satellites?

    To help you get started, I'll point out yet another irrefutable fact.... with my perfectly plumb pole in the Los Angeles area, the elevation adjustment on my Slimline dish mount will not move my dish on along an axis that is even near to being perpendicular to the arc of the satellites, and yet there are locations in Texas where with a perfectly plumb pole the elevation adjustment will move the dish along an axis that is exactly perpendicular to the arc of the satellites.

    I eagerly await your answers to the above questions. Since I am so wrong :lol:, I'm sure it will be a piece of cake for you or anyone else to point out what is false about my statements above, and to answer my very simple question about how the axis of the elevation adjustment must relate to the arc of the satellites in order for it to be "correct".
     
  3. Jan 4, 2010 #203 of 217
    doctor j

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    Cartrivision!

    COME ON MAN!!!

    Your statements on celestial geometry are correct.

    However !, it is also correct, that for the uninitiated, a starting point that is "off axis" ie not plumb ,makes adjustments more difficult. They become 3 dimensional rather than 2 dimentional and thus much more difficult for the "average user".

    If you insist on being"correct" as opposed to being practical, there is no defense. You are right! Your logic is unrefutible!

    However the common man will still spend hours trying to find his simple satellite TV service w/o success if his mast is not nearly plumb.

    If the mast is plumb, and correct AZ,EL,TILT co-ordinates are known, "EVEN A CAVE MAN CAN DO IT".

    I hope you feel GOOD by being CORRECT.

    Doctor j
    "an unsupportive, equally anal retentive , obsessive-compulsive nerd"
     
  4. Jan 4, 2010 #204 of 217
    Doug Brott

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    Not sure why we needed to resurrect a 6-week dead thread ..

    Either way .. I eyeballed my mast threw a dish on it .. put a receiver and TV close by and tweaked it using the dithering method .. up in the high 80s low 90s in just a few minutes and called 'er good. Next!
     
  5. Jan 5, 2010 #205 of 217
    cartrivision

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    I'm sorry, but that is just a "hand waving" explanation that not backed by any logical statements of fact.

    As I have pointed over and over again, for different locations on the Earth's surface, the axes of adjustment of a dish mount that is on a perfectly plumb pole will have an different relationship to the arc in the sky on which all the geostationary satellites lie.

    That simple fact that nobody can refute means that every single plumb pole installation has adjustment axes that are different (don't move in the same direction) for every different pole location.

    Given the simple irrefutable fact that every installation has their own unique axes of adjustment that are not the same as anyone else's axes of adjustment (i.e. they all are oriented/skewed differently with reference to the arc of satellites), how can all of those different orientations of the az/el adjustment axes ALL have some supposed "correct" direction of movement that you and others say makes adjustments "less difficult for the average user".

    I keep asking that question and nobody can answer it. Can you?

    How can the adjustment axes of all the plumb pole mounts all be oriented differently and at the same time all be oriented to move in the "correct" direction?

    I keep asking that question and nobody can answer it. Can you?

    What is the "correct" or optimal orientation of the adjustment axes with relation to to the arc of satellites that is being aimed at?

    I keep asking that question and nobody can answer it. Can you?

    You clearly think that there is some "correct" orientation of those adjustment axes, so what is it? How should such optimally oriented elevation and azimuth adjustments move the dish in relation to that arc of satellites?

    Should the elevation adjustment on the dish mount move the dish along an axis that is perfectly perpendicular to the arc of the satellites? If not, what is the correct direction for that axis of adjustment?

    Why can't anyone answer these questions?

    If there is a "correct" or "optimal" orientation for the az/el adjustments as they relate to the positions of the satellites that are being aimed at, please state what it is.

    The inability of anyone to answer these simple questions effectively shows that there is no one "correct" orientation of the adjustment axes, and furthermore if there was, putting the dish mount on a plumb pole couldn't possibly insure that one correct orientation of the adjustment axes since every plumb pole in every different location points in a different direction.
     
  6. Jan 5, 2010 #206 of 217
    cartrivision

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    Because people keep posting "hand waving" explanations of what a plumb pole does for you without providing logical factual statements supporting that supposition, and because every time I ask someone to demonstrate any factual error in the simple statements that I keep making which support my contention, nobody can demonstrate any such factual error, and they instead just repeat their error ridden theories without any supporting logic.

    If all this bores you and/or you don't care to learn why a plumb pole does not provide an optimal or "correct" orientation of the dish adjustment axes, or you prefer to believe (as incorrect as it is) the supposition that a plumb pole gives you and everyone else some kind of optimally oriented dish adjustment axes (which are somehow all correct and all the same despite being referenced to poles which are all pointing in different directions), continued reading of this thread is probably not advisable.
     
  7. Jan 5, 2010 #207 of 217
    veryoldschool

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    cartrivision,
    You went off the deep end over this so long ago, I simply passed over your posts for a long time, but why in the world you've decided to drag this up again is a mystery. :shrug:

    I've posted from my first that the pole doesn't need to be "plumb" [plumb is like being pregnant, you are or you're not, as plumb, it is or it's not, there is no degree of this].

    If you start with a "plumb" pole, then you can align the dish quicker, as the listed settings for the location will work with less "fiddling".
    The farther out of plumb the mast is, the more you need to compensate by deviating from the listed [basic] settings. The installer needs to have an understanding of which setting needs to be adjusted to compensate for the lean.
    This could/will take a bit more time to do.
    If you're not being paid or are being paid by the hour, you can spend all the time you need to get the dish aligned well.
    If you're being paid a flat rate for the job, then you want to do the job as quickly as you can, and "fiddling" with the dish is costing you money.

    Without going into astrophysics, has this answered your questions?
     
  8. Jan 5, 2010 #208 of 217
    Doug Brott

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    Yeah, thanks for that tidbit .. :rolleyes: .. But really, everyone else did move on. You're the only one left at this point .. So I will not return and I encourage others to do the same as the point of this discussion is no longer the topic of this thread.
     
  9. Jan 6, 2010 #209 of 217
    cartrivision

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    Because people keep saying that there is a "correct" orientation of the adjustment axes that allows the fine tuning adjustment axes to be done on "one axis at a time", but nobody who says that can describe this supposedly "correct" adjustment axes orientation in relation to the arc of satellites that we are aiming at.

    I'm aiming at satellites in the sky, so if there is some "correct" orientation of the axes of adjustment, I need to know what it is in relation to the objects that I'm aiming at. I don't even need an explanation of how a plumb pole will achieve that correct orientation of the adjustment axes with relation to the satellite arc... I just want someone to tell me what the "correct" orientation is using the constant position of the satellites (which defines a constant arc in the sky) as a reference point.

    I'll stop responding to the "correct adjustment axes orientation" crowd and declare myself wrong when any one of them can answer that very simple question.

    You are not saying anything that I disagree with. I have said long ago that that there is one and only reason that a plumb pole would ever matter, and that is that it allows you to use the AZ/EL numbers calculated for your unique location to get the initial rough fix on the 101 satellite. Those numbers are calculated for a plumb pole, but they could just as easily be calculated for a pole that was leaning to the north by 10 degrees, and everything would still work the same.

    Other than for that purpose of using those calculated numbers to get the rough fix on the 101 sat, a plumb pole is completely irrelevant to the rest of the adjustment process... which is what my whole argument has been about.

    It doesn't make fine tuning adjustments happen on a singular axes of any coordinate system that has a constant fixed relationship to the objects being aimed at... it cant, because a plumb pole defines a differently oriented coordinate system (in relation to the satellite arc) from every different location on earth.
     
  10. Jan 6, 2010 #210 of 217
    veryoldschool

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    With three axis adjustments [right/left, up/down, & right/left rotation], one could mount a dish upside down or sideways and if they didn't run out of adjustments, could align the dish.
    Let's look at a condition where there needs to be "some correlation".
    If the polarization of the beam is linear, and using a single LNB dish, one could use the two axis adjustments and have the dish centered on the target SAT, "but"still have the LNB caulked off axis of the linear beam. If there was a tilt adjustment, you could compensate, but if you don't have one, the the mast/dish/LNB must be "plumb" for the LNB antenna to be inline/phased with the SAT beam polarization.
    This isn't needed with a circular polarized beam. 101,110,119, & 99/103 are circular, so "tilt" is only to align the LNBs to the arc of the SAT spread.
    From reading the forums, the 95 SAT uses linear polarization. This may be the source of the "plumb mast" requirement.
     
  11. Jan 6, 2010 #211 of 217
    cartrivision

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    That's correct. I believe that's why DirecTV chose to use circular polarization instead of verticle/horizontal polarization... because it allowed the old single LNB dishes to be aimed without having to have a skew adjustment on the dish mount.

    That's not completely correct. An out of plumb mast doesn't prevent you from getting the correct skew. Even with a severely out of plumb mast, once the center LNB is aimed directly at the 101 satellite the dish mount skew adjustment will still rotate all the other LNBs while leaving the center LNB locked on the 101 satellite, so it's just the same as with a plumb pole... the dish has to be rotated on the skew axis until the arc of the LNBs lines up with the arc of the satellites.

    After that skew alignment has been done (and it can be done regardless of whether the pole was plumb or not), then any LNBs that depends upon horizontal/vertical polarization will be correctly oriented to the satellite, but as you pointed out, the skew adjustment would still be necessary to align the arc of the LNBs parallel to the arc of the satellites, even if there are no h/v polarized satellites. The only thing that isn't absolutely necessary is a plumb pole (while recognizing the fact that the rough numerical settings for AZ, EL, and Skew are calculated for and only valid for a plumb pole, but also while recognizing that the "correct" numerical settings could be also calculated for any out of plumb pole based on the additional parameters of how many degrees it was out of plumb and in what direction).
     
  12. Jan 6, 2010 #212 of 217
    veryoldschool

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    What I said is "completely correct", and you seem to have said the same thing in your "correction". :confused:
    Now as for your last part: I don't know if the single LNB dish for the 95 SAT has a tilt adjustment. If it does then "sure", but if it is like the single LNB dish for 101, then it doesn't.
     
  13. Jan 8, 2010 #213 of 217
    cartrivision

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    What wasn't "completely correct" was your statement that a plumb mast might be required for the skew adjustment to work correctly for aligning the dish for any satellites that use horizontal/vertical polarization.

    That's not correct. Even if the mast is significantly out of plumb, once dish is adjusted so that the 101 LNB is pointing at the 101 satellite, then the skew adjustment will rotate the dish about an axis centered on the 101 satellite and LNB, and then with that established, adjusting the skew so that the arc of the LNBs is parallel to the arc of the satellites will also give you the correct orientation for any satellites using H/V polarization... regardless if the mast is plumb or not.
     
  14. Jan 8, 2010 #214 of 217
    veryoldschool

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    [last round] "What I said was": if there wasn't a tilt/skew adjustment, like the 18" round single LNB dish.

    And with this "I give up" :nono:
     
  15. cartrivision

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    That might be wise, because what you said was this ....

    The last sentence of that statement is what was incorrect.

    As I pointed out, the tilt adjustment does not depend upon the orientation of the mast for it to work. Once the dish is centered/pointing at the 101 satellite, regardless of whether or not the mast is plumb, the skew adjustment will still rotate the dish about the axis of the vector that points to the 101 satellite, which is all that is required line up the other LNBs with the arc of the satellites, which is also what will provide the correct polarization alignment if any of the satellites are using linear polarization.
     
  16. sstv

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    Hi All
    This has gone on long enough.
    MODS, PLEASE CLOSE THIS POST
    Thanks
    SSTV
     
  17. Tom Robertson

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    At the request of the thread starter, this circular logic has been closed.
     
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