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best way to take off - magnetic interferences - IHHO

Discussion in 'General Discussion' started by tknquad, Jan 31, 2014.

  1. tknquad

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    I went to the shop in Rome to buy a props balancer and I had a chat with the owner, a very helpful guy.
    I told him about the problem between DJI China and USA. No comment here.
    Then we talked about flyways and best way to take off, and he gave me some piece of advice which I would like to share and discuss with you.

    1) flyways. he told me that flyways are a major problem of anything RC-fliying and the main reasons are magnetic interferences. and, among them, one reasong usually to be considered are solar storms which are source of great magnetic changes. Therefore the solutions is to install on his own phone an app which tell us about solars storms in every moment. HE told me also to check if at the time when a flyway occurred, there was such a storm. this come from his long experience in Flying anything in the past.

    2) best way to take off. He told me that after the usual checks and after lights are green, best way to take off is in manual mode and only after the Phantom has left the ground, switch to GPS. This is because the earth is a gigantic magnet and so it produces interferences. It is best to swtich to gps mode only after the Aircraft is in the air

    I believe these are vauable information that I want to share, discuss and comment with you and match with your experience.


    Tkn
     
  2. JTheed

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    I'm curious, that if you take off in Manual Mode, and then switch to GPS, will it have a Home Location then?
     
  3. LandYachtMedia

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    Unfortunately that description isn't accurate regarding the earths magnetic fields affect on an autopilot system such as what the Phantom has. While as a concept it is correct that the field ebbs and flows on a macro level that causes the earths magnetosphere to change a lot those effects get smaller as you get closer to the earths surface. Even a severe geomagnetic storm effects a compass in the range of tenths of a degree. If that was enough to send a Phantom into a spasm then these quads would be unflyable pretty much anytime.

    Now if we start talking about electromagnetic interferences then things get a lot more interesting. Where the effects of EMI will be most severe with a solar storm is with the GPS signals. That is mostly caused by the ionization of the atmosphere that happens from the extreme UV burst of the solar flare. Those effects start affecting earth in a matter of minutes after the flare where the magnetic storm itself lags the flare by a couple of days.

    So anyway, the science doesn't support those thoughts as they are stated.
     
  4. ianwood

    ianwood Taco Wrangler
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    I think for this to be true you have to be in the polar regions where traditional navigation gets tricky all together. There are some other areas where the earth's magnetic field gets a little "interesting" but it is fairly static normally. It also extends well beyond the ground's surface thankfully so taking off in manual should have no impact unless you're parked over something ferrous that will effect the compass.

    Solar events can cause disruptions when charged particles enter earth's atmosphere but they're more likely to upset GPS and other radio frequency based systems. There were two R2 class events this past week both with very limited ability to influence RF performance. I've noticed no increase in reports of flyaways associated with these events.

    And LandYachtMedia is right that electromagnetic interference is much more likely to be an issue for the compass. As well, man made and naturally occurring ferrous objects.
     
  5. tknquad

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    I want only to underline that his remarks are based on experiences. In his opinions if you check when flyaway occured you will discover that it was during a magnetic storm. It is Worth considering it.
    I hope to never have occasion to check it.

    So said, I was more interested in another topic, which is related to the interferences.
    In your opinion a mobile phone, which I would like to use as a gps tracker, attached to the body of the P2, will give interferences if switched on? Of course I will switch off the WIFI. In his opinion there are no problems, as it is on the band of 933 and not 2.4.
    What's your exprerience or thoughts?
     
  6. ianwood

    ianwood Taco Wrangler
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    A strong magnetic storm would have an impact on many things. Thankfully those are pretty rare. As for strapping a phone to your Phantom, it's been done but I would suggest not doing it. Your phone will have multiple frequencies not just 933Mhz. And even if the frequencies are all far away from 2.4GHz, at very short range the phone will emit a wide spectrum of RF interference as well as EMI, etc. Remember the sound of holding a GSM phone too close to a speaker and the beeps would get inducted into the signal? Just think of that.
     
  7. ElGuano

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    I think the only reason you might need to take off in manual rather than GPS is if you're taking off from a ferrous surface. And even then DJI just recommends you take off normally and let the phantom compose itself in the air. Personally, I think the risks of messing with manual for takeoff before you are well familiar with how it operates in flight are way greater than the risk of some on-ground compass affecting issue.

    And the earth's magnetic field argument just doesn't pass the smell test to me. It doesn't diminish significantly 10 ft from the ground, and how high is the van Allen belt again? I don't recall ever needing to put a compass on the ground in order to find out where north is?
     
  8. FlyingFanta

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    I'm curious about this. My concern is that without a good home lock, that it would fly away to some random location if something ever triggers fail safe. I understand that the location is locked when it first lifts off in GPS mode.
     
  9. Hiway

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    Another problem I have been considering as a possible cause of some flyaways is CLI. (cumulative leakage index)

    As an old communications field tech, and having spent a lot of time bringing cable plants up to FCC regs in the past, I can personally attest to the frequency (no pun intended) of "dirty" cable plants out there in the world.

    Many times it the cause of an old house where a disconnect was never done hard (literally pulled from the tap and terminated with a 75ohm dead end) and it is blasting signal like a monster. Take an apartment building where there may be hookups left in, or even an old line extended or trunk amp and with bad fittings, the diode effect from old connectors, and the myriad of ways people find to splice inside cables with crap radio shack rg6 and rg59 fittings, and the CLI can pump out tremendous volumes causing CSD and CTB issues (mixing of frequencies causing other frequencies)

    Just a thought... not that everyone has a CLI meter, but if you know a cable tv tech, have him check out your flying area if it is near any place that has cable running through it- even rural aerial lines can have severe leaks out in the middle of nowhere that would cause a problem.
     
  10. FlyingFanta

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    Dude, I can't even get the cable tech to come to my house on time and you want me to find one to scope out an airfield.

    :lol:
     
  11. Hiway

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    Comcast? :lol:

    You might be surprised... you see, if all they have to do is walk around an area with a handheld meter and listen for alarms, then that is not work... the problems begin if there is leakage, and he has to fix it.
    The catch? Find a noob... and most of them are, because due to FCC regs, if it is a big enough leak to cause an issue with a Phantom, then it is big enough to cause a problem with communications, and thus the ISP HAS to fix it. (depending on level of leak)
    The key is to know if the area is dirty or not to rule it out. That takes a few minutes. Those guys are dirt poor... $20 will have them out there I bet.