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Sudden Loss of Satellites below 6 got my heart beating fast!

Discussion in 'Phantom 2 Vision + Discussion' started by Beaugolfs, Aug 17, 2014.

  1. Beaugolfs

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    I just wanted to share my experience and lessons learned from the other evening, Then I experienced what happens when your Phantom Vision 2+ unexpectedly drops below 6 satellites when over 1,200 feet down range. I was flying in NAZA mode and had a confirmed home point set, which I verified in my normal pre-flight routine. Fortunately, I was using the new beta version of iRec on my iPhone, so I captured a record of exactly what happened. Without that record, I am sure I would have lost a lot of confidence in the bird, which after 50 flights, I have had nothing but positive experiences until the other night, which in the end turned out to be a positive experience from a learning perspective.

    So, I took off with 7 satellites showing connected and was flying primarily watching the bird and not looking at my iPhone. I was just over 1,200 feet away at 130 feet up, when I noticed the bird start to drift or "fly away" unexpectedly. Now, I was looking at my phone, as I was getting ready to take a still pic, and in hover mode. However, I wasn't and hadn't been monitoring how many satellites I had locked into. So, when the started to drift in the wind I couldn't understand what it was doing, that is when I decided to flip the S2 switch to HL (all the way down to the 3rd position) and pull back on the right stick, which should have brought the bird back in my direction. Unfortunately, it started to pick up speed and fly very fast away from me, to right of where I was standing. So I immediately let go of the right stick, and while it slowed down it continued to fly away. Then it seem to stabilize, and I noticed from the radar that it was pointed in my direction. So, forgetting I had the S2 switch in the HL position, I pushed forward on the right stick attempting to fly it back in my direction. However, it then began to fly away again very fast, because the front of the bird was pointed at me! So, once again I let go of the right stick, decided I had enough, and flipped the S1 switch down into FailSafe and to my relief the bird finally started heading home. I was dumbfounded until I got home and viewed the iRec video on my iPhone, which explained everything. Please take a look at the video, which again is what was recorded on my iPhone. https://vimeo.com/103619686

    This was all caused, because I didn't realize I had lost GPS and Home Position and my actions of trying to trying to put my bird in S2 HL made everything worse! Fortunately, GPS kicked back in or I am not sure what would have happened?

    Lessons learned:

    1. Always check http://satpredictor.navcomtech.com/ to make sure I am flying at an optimal time of day with plenty of available satellites.
    2. Flying with only 6 or 7 satellites warrants staying pretty close to home, where I can always see visually the orientation of the bird. Flying long distance in any kind of wind with low satellite coverage is just asking for trouble.
    3. When the bird is moving, when it should be hovering, 1st check the number of satellites and ensure home position is still known. If the Distance shows N/A, and sats are < 6, then home is lost and you must fly as though you are in ATTI mode. So check the orientation of the bird, by looking at the radar and try to start flying back toward your position. Flying in HL will only make things worse if the bird isn't properly lined up, which in my case the other evening it wasn't.
    4. Always record my flights using iREC (sort of like a black box), which clearly helped me understand what went wrong. I had a theory that I had dropped below 6 sats, but without evidence, I would have never known for sure.

    Hopefully my experience and mistakes made here might help others. In the end, the Phantom Vision 2+, did everything it was designed to do. Thankfully this had a happy ending.
     
  2. Madwak

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    Re: Sudden Loss of Satellites below 6 got my heart beating f

    You were lucky that it got sat lock again cos if it hadn't the RTH would not have worked either. When you worked out that it was still flying away from you when you thought you were giving it the correct stick input you should have given it the opposite input to see if it started coming back, even better is to train yourself to think "check switches" if it isn't doing what you think it should.
     
  3. Beaugolfs

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    Re: Sudden Loss of Satellites below 6 got my heart beating f

    Yes, me too Geert! Appreciate your response.

    That is so true Madhak! I have posted before that I wish DJI would provide and audible alert anytime you fall below 6 Sats and become at the mercy of the wind. I would have instantly realized that S2 and HL would not have worked. It was my mistake for not checking the sat count first, before flipping the S2 switch to HL. I can't help but wonder how many so called fly aways, have started like mine did. To your point, the GPS kicking back in saved my butt. Again, if I would not have had the iREC recording to go back and review, not sure I would have known for sure what happened. You can see from the video it all happened pretty fast! In hindsight, I probably should have titled this "Fly Away that really wasn't". I could see others, with only about 50 flights under their belt making the same mistake. I will never take Sat lock for granted again. Thanks for your response.
     
  4. smokiespliff

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    Re: Sudden Loss of Satellites below 6 got my heart beating f

    It was a horrible feeling the first time that happened to me. Fortunately I was close to it and realised that I only had 5 sats and landed, despite having 7 when I took off. That experience, coupled with 1 more perplexing drop below 5 sats prompted me to come here and post this thread to which I found the solution. I can see in your vid that you were recording and just about to stop and take a pic instead. I bet that if you had stopped recording you would have jumped back to 7/8 sats and carried on none the wiser!

    Follow the advice in that thread and try again!
     
  5. dannytroy

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    Re: Sudden Loss of Satellites below 6 got my heart beating f

    Funny in that wide open area you only got 6 -7 satellites. I would consider the metal foil tape mod described in this video:
    https://www.youtube.com/watch?v=q31s6NDFUlA

    I did the mod and seem to get better GPS performance. Considering your experience, I would definitely do that mod.
     
  6. Wally

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  7. Cocoa Beach Kiter

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    Re: Sudden Loss of Satellites below 6 got my heart beating f

    Excellent post... Thanks
     
  8. Beaugolfs

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    Re: Sudden Loss of Satellites below 6 got my heart beating f

    Yes dannytroy, when I got home and watched the iRec video on my iPhone, I decided to check the http://satpredictor.navcomtech.com/ website, which was showing a day low of 6 Sats for the time and area I was flying in. I have found this site to be spot on for my area. This just in.......it works better when you check the satpredictor site before you go out and fly. ;) I just wish that site didn't require Flash, so I could use it on my iPhone or iPad. I usually never have Sat problems, but the Satpredictor indicates on average about 2 hours each day, usually separated by 8 hour blocks, there is usually a lull in coverage (showing down to 6) that last for about an hour. I just need to avoid flying during those times, or fly nearby.

    If I lived in an area, such as the mountains or valleys, I might try the foil mod. When and if I try it, I will test it during those low predicted times of the day and see what it buys me.
     
  9. Intruder101

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    Hey Beaugolfs,

    I was wondering if you can tell me more about the iREC? Where would I find it and what is the cost, if any?

    Thanks

    Sorry if you mentioned it somewhere else...
     
  10. jumanoc

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    Here there is all you need. Check link for downloads an video... How To:
    https://emu4ios.net/
     
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  11. jumanoc

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    Your video link is not available...
     
  12. Intruder101

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    Thank you, will be looking into it.

    Thanks for the fast reply.
     
  13. kirk2579

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    Do NOT wait to do foil and antenna upgrade if you like to fly out of los and long distance.
    what else can you do for 10 dollars that gains the quad so much better performance in gps lock and stability
     
  14. Prowler

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    I can't get these links to work.?

    I am sure this would solve and prevent many 'fly aways'.
     
  15. volito

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    Wouldn't CL have been easier to implement?

    Course Lock, as I understand it, needs only compass, not a GPS lock. As far as a GPS availability program for IOS, try GPS Plan (free app).
     
  16. yorlik

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    I agree. i always take off pointing N so I know I can count on CL if needed for recovery in this kind of case. I have had to use it multiple times. everyone should practice with CL to learn how it can help in this kind of case.
     
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  17. RoyVa

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    I would double check the GPS plug that goes to the main board. There have been reports of it vibrating loose and dropping satellites. Some guys are wedging material between the male and femal plug to ensure a tight vibration free connection. Just a little extra insurance.
     
  18. DrJoe

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    Perfect description of the "flyaway" problem. Great job realizing what to do. CL will save you in these situations.
     
  19. pogo1969

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  20. kirk2579

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