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How to avoid DJI Phantom Fly-Away by Colin Guinn

Discussion in 'General Discussion' started by Fdnyfish, Dec 1, 2013.

  1. Fdnyfish

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    [youtube]http://www.youtube.com/watch?v=2bxjL7wFyb8[/youtube]
     
  2. Ksc

    Ksc

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    What he said makes sense. I'm sure some people will argue that they were flying in a field in the middle of nowhere and no signals could have taken over. I would think that if you are in the middle of nowhere but have great cell phone strength, you have scattered interference.
     
  3. Eagleeye9

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    Thanks,

    Thats put my mind at rest a bit that there is at least a fix in the firmware for stronger signal taking over. Incidentally, when was this video published?
     
  4. OI Photography

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    Yesterday (Nov 30)
     
  5. mediaguru

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    Interesting.

    Watch the video and caption at 5:10 or so.

    The audio says "what we've done to combat this issue" and the caption says "what we've done to combat this fly away issue."
     
  6. discv

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    Thanks, Fdnyfish, for the headsup.

    But can anyone clarify this for me? The rapidly flashing green LEDs, confirming home location, I always wait for before take off.
    The video states that the home location will again confirm just after take off.

    I have never seen this second sequence- probably due to being in a state of panic at this point!
     
  7. jadebox

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    There are a lot of minor differences between the captions and what he actually says. I don't think that you can read anything into that.

    -- Roger
     
  8. ElGuano

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    There are a couple of distinctions here.

    What he's saying: "If you wait for the alternating red-green blinking light to become just green-blinking, then take off, you'll eventually get the rapid-green-blink that tells you a home point is marked." IMO that's not the best practice, but it'll probably work for someone eager to just get the bird in the air. What you should do is wait for the alternating blinking light to only blink green, and then continue to wait a few seconds until you get the 15 rapid green blinks. THEN you take off.

    The second part, not mentioned, is that you'll often see the 15 rapid green blinking sequence TWICE, if you're set in GPS mode. The first time it will happen is probably while the red-green alternating blinks are still happening. That's probably a compass/course lock indicator. The second time you see the rapid-green blinks should be after the alternating blinking becomes just green blinking(6+ satellites locked). That should be your home point/GPS lock indicator. I wait for both to happen before I take off.
     
  9. The Editor

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    1974 :lol:

    Actually, if you listen to what he's saying I think all he's describing is the 'Advanced Receiver Protection' that has been around in the FW since about v3.12.
     
  10. OI Photography

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    Interesting. I've never had anything other than the single rapid-green sequence after power-up, and I always wait to take off until I see it. It obviously happens much sooner with a warmed-up system...the first flight can take a full minute to obtain the lock, but later flights in the same session (2nd/3rd batt, etc) get the lock in ~10 sec.

    Agreed :)
     
  11. Dave Pitman

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    Agreed. Then, at liftoff, I hover close for 20 seconds or so, and observe the Phantom to see how good the gps hold is working. If it is drifting too much, I set her down and repeat the sequence. If it gets a marginal lock the first time, it is usually better the second time...I don't know why.

    The point is that you should take the time needed to know to the best you can that the system is working before heading out.
     
  12. Dave Pitman

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    If the Phantom heads off on a fixed bearing (that it interpreted from an interference signal) as fast as it can go for 10 seconds, how far away will it be when it decides to hover? Better have fpv, or binoculars!
     
  13. ElGuano

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    But it might just fly off in the OTHER direction.

    IMO, ARP is likely of limited use. If your Phantom rx gets swamped with a competing RF signal, for ARP to be useful, it MUST:

    1. Be an unchanging, static signal for a continuous 20 seconds.
    2. Not be intermittent so that it might be overtaken for a fraction of a second by your actual TX.
    3. Be sending a spurious signal to your Phantom to move in a "safe" direction for 20 seconds.

    I'm not an RF expert, but my guess is a cell tower, or power line, or whatever might overtake the Phantom, is going to break at least one of those rules, rendering ARP more or less useless.
     
  14. Dave Pitman

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    ARP has been around since May, nothing new.

     
  15. TPD

    TPD

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    I was scared a lot by these frequent flyaway reports. I would rate this as an official statement, that there is a problem with the DJI receiver which can get stuck and produce a permanent go ahead signal. This fits well to the more or less consensus, that using a third party receiver reduces the risk of flyaway to almost zero. I hope that all those who lost their phantom and GoPro get a free replacement now (some of us in the forum have got a replacement, others not)

    They probably do not want to replace the many receiver modules out there (which I think they should because an out of command quad is dangerous by itself) and made a fix in the flight controller. Makes somehow sense as the flight controller is obviously not stuck in a fly away event, otherwise the thing would fall out of the sky. However, it is only a workaround - your phantom may not fly away for more than ten seconds but within this ten seconds, it could fly somewhere where it is either destroyed or, even worse causes damage somewhere else.

    I have not found any information in release notes in which version they implemented this feature (or is this ARP, if so I am pretty sure that there were fly aways afterwards) - does anybody know this and have there been fly aways after this version was released?

    So, this is a great forum and we should continue to watch this issue, it scares many pilots as loosing 1000 USD is no fun for many of us and maybe DJI will tell us at some point the full story.
     
  16. Davek

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    Yeah.... I think it's odd that there is so many theories with no facts at all and nada until now from dji America with this guy who doesn't even do basic vids very well and waves hand over an issue that has been around for a long time. BTW.... how long has the Phantom been available? Has been longer than a year?
     
  17. BallisticPhantom

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    The cellphone tower story is bunk IMO. He must nave a special not so cell phone tower at his shop or in another country. All that rf could be an issue yes but it is unlikely that the 2.4 on that spread band could do that. If that were the case 2.4 would have been ban for rc long ago. A receiver issue allowing that interference to effect it is much more likely.
     
  18. miskatonic

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    DJI is in China.
     
  19. ElGuano

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    Colin is at DJI America, they're in Austin TX I believe. That office does sales, marketing, PR and tech support for the Americas.
     
  20. OI Photography

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    I think Colin was referring to their office in Austin, there is a big cell tower in the parking lot there.

    While most cell frequencies in the US stay below 2GHz, some "4G" service is now starting to squeeze into the already-crowded 2.4 space as well. If you try to fly within 100m of a tower with several strong transmitters of that type, I'm sure the Phantom's receiver can easily be blinded.