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Calibrate

Discussion in 'General Discussion' started by Larry L, Dec 5, 2014.

  1. Larry L

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    have another noob question. I was taught To Calibrate my compass every time I fly. I have been reading & looking at some videos. There are several that say not to calibrate unless you are more than 200 miles away from last flying location or having flight problems, etc. My question is if you do not calibrate before flight & you loose contact & try RTH, how does it know where to return to? I was under the impression that calibrating the compass before flight set your RTH point. If not, what sets the RTH point?
    I appreciate all the help trying to understand this complicated machine.
     
  2. Larry L

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    I think I found it. Is it when you power it up & it locks on to 6 or more satellites?
     
  3. Larry L

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    Dirkclod, It has helped, I think :? :? Ok, so if I just spin it 360 degrees ( level) Horizontally & get the green light, I am resetting HP? If I do not turn it on the nose & rotate it 360 degrees then I am not resetting compass? I thought both steps were to reset compass.

    When I turn on, after warming up, I get the quick green flashes, HP has been registered? but I do not need to calibrate unless getting yellow & green flashing LEDs? I always calibrate before flight & fortunately I have not ran into having to recalibrate.
    So when it gives you the quick green flashes, I know it is ready to fly but is that also letting you know that your RTH has been registered? So really I do not need to do all the horizontal & vertical dance unless I am getting the red & yellow flashing? I think that is clear as mud!
    Again, thanks for all the help!
     
  4. sbjr0203

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    Only time I do is if I'm not getting enough GPSs, been hundreds of miles from last location of calibration and no issues
     
  5. 4wd

    4wd

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    You are confusing two separate things here and it is dangerous.
    Compass calibration has nothing to do with homepoint.

    Homepoint is set from the inbuilt GPS unit.
    When the phantom knows which way it's pointing it will rapid green flash.
    When it has enough satellites for solid GPS fix it rapid green flashes again.

    The compass calibration works in conjunction with these during flight mainly.
    It won't hurt to do it at each new location but there's no need, and there is a risk of doing a 'bad' one if something causes an unusual compass disruption at each spot.
    Compass can be badly messed up by strong magnets. A common risk area is car radio speakers which have strong magnets.
    Anywhere near those and you need do it. Also after a week or two of non-use I might do it, or after moving more than 10 miles or so.
    With the Vision Range the app tells you if it needs doing.
    Phantom One at least will flash Red/Yellow if it needs doing.

    There's no need to do it every time you fly, but calibrating *when required* is a vital part of pre-flight routine.
     
  6. Meta4

    Meta4 Moderator
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    Just to confirm what 4WD said ...
    Spinning the Phantom is all about the compass and has nothing to do with GPS or Home Point.
     
  7. Great Pumpkin

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    And my practice is to wait for take off until I get slow steady green flashes and only when the Phantom has acquired 8 or more satellites. Others may get away with fewer, but I prefer not to chance it. Earth's magnetic field does not vary over short distances or over short time periods. Have a look at an isogonic chart to see that you have to go over 200 miles in an east or west direction to get enough of a change in the magnetic field to require a compass recalibration. Me? I don't calibrate unless I've gone about 100 miles or always after upgrades of all sorts, but then I live in the SW U.S. If I lived east of the Mississippi River, I'd calibrate over shorter distances, because the lines of magnetic field are closer together.
     
  8. Larry L

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    Thanks Pumpkin, That does make a lot of sense with the earths magnetic field. I just went out & flew without doing a jig. nervous at first but once I was flying for a bit & just steady blinking green the whole time, all of a sudden it was not a big deal! I started off with 8 satellites & steadily picked up several more. I too do not like to take off until 8. The more the better.
    Have you ever been sure of something & then read things or thought about it & all of a sudden nothing makes sense? Well that was me :shock:
     
  9. Larry L

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    :D That is what this forum is all about :D I really enjoy all the info here!
     
  10. Happyflyer

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    Larry L,
    Are you aware there are two parts to that "compass dance?"
     
  11. Larry L

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    Happy, yes I am. horizontally 360 & nose down 360. Is that what you are talking about?
     
  12. Happyflyer

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    Yes, you got it.
     
  13. Larry L

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  14. Meta4

    Meta4 Moderator
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    To illustrate .. these are the charts Pumpkin's talking about
    [​IMG]

    [​IMG]
    An error of 1˚ between your compass and your local magnetic declination is small enough to probably be insignificant.
    An error of 10˚ will cause problems.
    You can see from the charts how far you would have to travel to make any difference.
    Or how far you can travel without making any significant difference.
     
  15. Larry L

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    Thanks, I see. Looks SW is the place to be. :D