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Satellite Predictor Site

Discussion in 'Phantom 2 Vision + Discussion' started by Skynet1, Jan 12, 2015.

  1. Skynet1

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    Hello, all.

    I've got a question I thought someone may shed some light on, I was doing some testing this afternoon outside my home, and referred to the sat predictor chart beforehand, which indicated roughly (8) Sats available. However, I found I was receiving no less than 11 and at one point (14) from the camera app info., much to my surprise, as I very seldom acquire that many.
    When I finished testing I went back & rechecked the web-site and found that the satellites predicted had actually dropped to as little as 6 during this time frame of which again the camera app number never dropped below (8) during this same time period.
    Question, can the camera app be unreliable in this regard, which may explain why some have developed issues while flying only to indicate they had a relatively sufficient number of Satellites on there app at the time of the incident.
    How heavily should we be relying on the DJI camera App Sat info. in that regard ?, particularly when the app is suggesting a much higher number of satellites than may actually be available at any given time. Thoughts!
     
  2. msinger

    Approved Vendor

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    The GPS module in the Phantom is telling the DJI app how many satellites it's connected to. That said, I don't think the issue could be the DJI app.

    Or, are you suggesting the DJI app is not reporting what the GPS module is telling it?
     
  3. MrC

    MrC

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    Are you using http://satpredictor.navcomtech.com/ ?
    If so the elevation mask is very important. Default is 10. Try lowering it to 0 and see what you get...
    Basically once the bird is in the air the elevation mask is 0 or near to it.
    Elevation mask is the angle from ground to clear line of sight to the sky.
     
  4. Skynet1

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    In short, I actually was questioning the reliability of the information which is provided by the GPS module within the Phantom, as compared to specific information provided by the satellite predictor web-site. http://satpredictor.navcomtech.com/

    I was wondering why when using the above site, and entering my location etc. the graft had indicated approx.( 6-8) Satellites were avail. at my location at the date & time I was flying. However, the GPS module was obviously providing some different info. to the DJI camera app which had indicated (11-14) Sats were available at the time.

    Using the comparison described above, where the GPS module was indicating a much larger number of available satellites than that shown on the sat-predictor site, brought me to question the reliability of one or another of these sources and hoped that someone might provide some addition info.or reasoning to the discrepancies, point being a pilot may believe he/she has more than sufficient Sats to fly in GPS mode according to the camera app, when in reality the actual number may be much less presenting a safety issue.

    Hopefully, I'm being clear on this. : )
     
  5. Skynet1

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    To answer your question, yes, this is the web-site I was referring to when making my comparisons.
    In regards to lowering the default settings, I'm not so sure I understand how this is accomplished, but may be a valid reason.
    I'll look into it further, thanks.
     
  6. Meta4

    Meta4 Moderator
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    Your DJI Phantom app is telling you how many sats it is receiving up there where it is flying.
    Your predictor app is only a prediction (and an approximate one at that) - for ground level.
    If your Phantom says it has 10 sats - it has 10 sats.
    Your predictor app is the unreliable one.
     
  7. Skynet1

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    Thank you gentleman,
    That explains the difference MrC had initially pointed out. I went back onto the Sat-predictor site, and as suggested changed the default setting of the elevation mask from 10 to 0 to account for the ground level reading, and found the number of satellites available had increased an additional (4 ) sats during the same date & time. The elevation mask can easily be changed there on the site and had provided a more accurate accounting. Interesting, and very informative.

    Thanks much, MrC & Meta4 for your help. : )