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GPS Elevation Mask

Discussion in 'Phantom 2 Vision + Discussion' started by cruz_ctrl, Sep 22, 2014.

  1. cruz_ctrl

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    I just visited the satellite predictor tool and one of the input fields is the Elevation Mask (EM) which defaults to a value of 10 degrees.
    Does anyone know if the P2V+ has an EM setting and, if so, what that value is?
    In the online tool I bumped it up to 15 and the results were substantially better with 10.

    BTW, I learned a lot about GPS satellites just researching the EM. Interesting stuff...
     
  2. N017RW

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    The u-blox6's Receiver Description Protocol Spec sheet [page 195] lists 'Min SV Elevation' default as 5 degrees.
    It is recommended not to change it so hopefully DJI or their supplier has left it alone.

    Antenna aperture may come into play as well further increasing the degrees above horizon in which SVs can be "seen".
     
  3. cruz_ctrl

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    from what i read, going that low (5) is not recommended as it may lead to inacurate readings from the satellites due to noise. the usual setting was 10-20 degrees.

    so it is adjustable in the P2V+?

    haven't heard of antenna aperture. could you explain what that is, please.
     
  4. N017RW

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    The 5 deg is the mfgr. spec. I can't comment.

    It is not adjustable by the user, it is in the u-blox firmware. Don't know if DJI can access it either.

    Antenna aperture is basically a factor of the antennas sensitivity or gain horizontally across the area it is pointing. Much like the limitation your eyes have side to side. To see more you must turn your head left or right.
     
  5. cahutch

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    It's not just the receiver. In most locations you can't see that close to the horizon anyway due to hills or trees. 10 degrees is pretty low unless you're on the ocean.

    In the online tool, it tells the software that you can't see any satellite that is under x degrees from the horizon.
    So of course it will show you more satellites if you lower that number but you're trying to predict what you will actually be able to see in your location.

    If I ignore the trees, I figure the hills around me to the east and west are at least 10-15 degrees.