That ilusive GPS lock

Posted by Juan Soler on March 31, 2015 at 3:54am

It seems that I am unable to get my IRIS+ to obtain GPS lock and consequently the device will not arm. 

I am getting 1.99 HDOP consistently but the indicator LED continues to remain in the bilking yellow state,

Naturally enough, I get the old two tone error response when I try to start the motors.

So I am at a loss to explain why locking GPS should be so elusive.  The device initializes fine and this is evident by the parameter dump on the MP.  I have removed the geo fence to see whether there was any change but this has yielded no joy. 

This is an out-of-the-box IRIS+  any ideas out there?

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Replies

    • Mark Stanoch > Juan Soler April 1, 2015 at 7:47am

      I am getting GPS lock but I can't predict the time to do so.  Sometimes it takes less than a minute and at other times it requires 7+ minutes.  The strange part is that it is from the same location each time.  I even changed the GPS_HDOP_GOOD parameter to 180. 

  • Juan Soler April 1, 2015 at 2:38am

    Well I followed all the advice (Holt's instructions to the letter) looked at the videos and read the discussions, then I went out and placed the IRIS on a flat surface - powered the Tx and connected the battery.  I walked away and left the the LED blinking its repetitive yellow message.  

    An hour went by, no change.  Two, three four, yes, I left it out there for six hours and it never acquired a GPS lock.  So I am thinking I either have an issue with this unit (fault) or something much more subtle is going on here...like I am missing something really basic.  At this point I really lean towards the former.

    • Holt Lipman > Juan Soler April 1, 2015 at 3:51am

      Juan, the flashing yellow sometimes indicates the Iris was disturbed during the initialization process... those 10 seconds immediately after plugging in the battery... try once more... unplug the battery... place the Iris on the flat, level, not near any metal, view of the sky surface... insert the battery into the tray...  plug in the battery... don't touch the Iris for at least 10-15 seconds...

      If the Iris continues the Yellow at that point... Follow Michael Burmeister's suggestion about Mission Planner, and ensuring the GPS is there and connected.  You might need to contact 3DR support as well... they are extremely helpful...

    • Juan Soler > Holt Lipman April 1, 2015 at 5:16am

      Understand.  I will give it another go.

    • Erik Graham > Holt Lipman April 1, 2015 at 4:46am
      Yes. As mentioned a couple times by a couple people here, don't disturb the Iris for the first few seconds. Sometimes just the act of plugging the Iris in to the battery can shake it around too much. That's why I steady it with one finger if its shaking or swaying after I plug in.

      I much prefer the Phantom batteries by the way. Easy to click in.
  • Erik Graham March 31, 2015 at 6:57am
    The very first lock may take a long time. It's a one time thing. Then you will find it gets lock within a few seconds - much much faster than a DJI. You'll be amazed (I certainly was) at how much faster it gets GPS lock than a Phantom. It will even get lock indoors sometimes. The GPS on my Iris+ is much more accurate than on my Phantom (which I don't even fly anymore).

    Be careful about bumping or shaking the Iris after you connect the battery. It's a quirk of the Iris+. I always quickly plug in the battery, then carefully steady the Iris with one finger if it is swaying or just go hands off for a few seconds. Once it goes through those first 4 or 5 seconds of boot up, you can pick up the Iris+, move it around, etc. but durring the first few seconds of boot up stay hands off. To be honest I'm not sure you have to be this careful, but it works for me.

    Since its a new Iris+, you might need to calibrate the compass. Probably not. When you are in loiter, if it seems to circle in place (they call it toilet bowling), then you need to calibrate the compass. Unlike the Phantom, this is not something you will need to do regularly. To calibrate the compass, follow this video: https://www.youtube.com/watch?v=oD9Z9IR2TNU&sns=em

    Other helpful videos can be found on 3DRs YouTube page: https://m.youtube.com/playlist?list=PLszd_sCs2VsLLqvMM-_ixdkDH5d-k7dqb
    • Juan Soler > Erik Graham April 1, 2015 at 2:23am

      Thanks for the helpful links.  Much appreciated. 

  • Juan Soler March 31, 2015 at 4:42am

    OK thanks.. 

  • Holt Lipman March 31, 2015 at 3:59am

    There are a few 'requirements' to obtain GPS lock and arm... these are especially true if you are trying to obtain lock for the first time.  

    1) Be patient.  The last time the Iris had lock was in Mexico... it takes a few (up to 15) minutes to obtain lock.

    2) As open a view of the sky as possible

    3) Away from metal objects, and on flat/level surface

    4) do not close the battery door after plugging in the battery.  Wait 30-45 seconds, then you can close the door.  Iris needs to be completely still for that first few seconds after you connect the battery.

    5) wait... 15 minutes hasn't passed yet...

    • Juan Soler > Holt Lipman March 31, 2015 at 4:41am

      Thanks, I will try this:)

       I will need to understand why this is the case for the IRIS - never had this problem with DJI or MK.  

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