Mobius Action Cam RF interference with GPS

Discussion in 'Walkera Cameras/Videos' started by chase, May 1, 2016.

  1. chase
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    chase Member

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    For those using the Mobius Action Cam with their birds you might find this interesting.

    I stumbled upon this article which included the posted video demonstration which shows the RF interference to GPS when in close proximity to each other.

    They're promoting a shielded case for the Mobius if interested, if not, their demonstration video seen below gives validity for the need of shielding. Especially if like myself, you're considering using the Mobius as an onboard camera.

    Here's the video demonstration:



    And here's the link to the article if you care to read it.

    Shielded Mobius Case now available.

    For the DIYer in some, here's a DIY Mobius Shield posted over on RC Groups by member AustnTexan on his RC Groups blog.

    A pic of what it looks like.

    [​IMG]

    There are other DIY RF shielding posts out there, just Google it to find more styles.

    Over at FPVLab who made a similar one for the GoPro stated that grounding the shield wasn't necessary.

    Important note was that on the GoPro version, it was found that RFI was leaking from the SD card slot. So a tab was made in the shielding to go over the slot, which ended that.

    Also mentioned was that the Mobius needed to be at least 6" away from everything else. Any closer, and that's where the interference came into play.

    Another note was that they found Aluminum shielding didn't do the trick.

    Better safe than sorry concerning whether or not to shield or not to shield imo...

    Shielding just adds an ounce of preventive measure to ensure against EM/RF interference from these devices.

    Considering the findings of the Mobius and GoPro RF leaks, it does make me wonder if the same isn't found of the iLook+ cameras.

    - chase -

     
    Last edited: May 1, 2016
  2. bjr981s
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    bjr981s Moderator Staff Member

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    As far as Shield Grounding Remember that, not grounding a shield will keep the RF noise inside the shielded object and increase the internal noise. Effecting the shielded object. If not grounded the shield cannot dissipate and divert the RF energy. Like putting a cosy on a teapot.

    The Testing of a Smartphone will identify if RF is interfering, but a smartphone is not a RC model. A smart phone is super susceptible to RF. The GPS is not of the same quality.

    An iLook Camera pumps out 800mw of RF at 5.8Ghz.

    Interference that effects GPSs comes from the wires (Antennas) connecting the GPS to the FC.

    Interference on wiring is dependant on the wire lengths. Contrary to general belief its not long wires, that are the worst, its wires that lengths are close to 1/4, 1/2, 1 and multiples of 1 of the bandwidth length. The natural best length for RF reception.

    All FV camera systems and model pump at RF at 2.4Ghz. The back channel to the radio and 5.8Ghz for the video stream.

    I have RF FPV transmitters ranging from 800mw to 2,000mw.

    Interesting that the mobious does output so much RF.

    Cheers
     
  3. chase
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    chase Member

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    Interesting analogy about the cozy on a teapot...

    And not that I know or studied RFI by any means.

    I would think since its been said "using the negative as a ground for the shield puts it back into object circuitry." Where you don't want it.

    That not grounding it, simply contains it within the shielded area.
    Having no where to go, and following path of least resistance, it would naturally dissipate... and the amount introduced back into the object circuit would be nominal.

    Just thinking out loud on that... by no means do I profess to know.

    The guys over at FPVLab I guess did all the testing on these type shields for the GoPro...

    The guy that made the Mobius shield was using it on a variable power UHF system from what I read.

    He said he's been using it for several flights, 7-8 at the time of his writing. Worked great without grounding it. No interference like he was getting prior to shielding it.

    Personally, I'm not that into the deep tech side of things on this.

    I'm letting the guys that are in the know, have all the testing gear and understand it a whole lot better than I do figure all that side out.

    I follow and grasp some of it along the way.

    My interest in this, is really to make my Scout that much more reliable.

    If I can shied the cause of the EM/RF interference. Add in additional protection, such as the Soft Ferrite rings... I'm hoping that will lessen if not not eliminate possible failures in this area.

    One thing not talked about that I thought about after mulling this shielding over and considering it for the iLook+ is the additional weight of these type shields.

    You can only add so much to these birds. And it adds up quick I've discovered.

    I'm going to see if I can find this copper foil their using. Or tape or whatever it is and get a better feel for what kinds additional weight making a shield like this we're talking about.

    It's definitely interesting though.

    I'm considering something like this having stumbled upon the MoPro case mods for the Mobius, which should allow the Mobius once the mod is done, to fit directly in the G-3D or 2D gimbal.

    More reading required.. lol
     
  4. bjr981s
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    There is 2 ways to think of a shield. Either absorption or reflection. Im thinking that the special copper shielding has different reflection and or absorption values????

    It stuff for the scientists. I can't even remember the math required. Its been a long time. :(

    I think that making the scout more reliable will be expensive.

    My parts to build the perfect Scout and Tali runs into the 3K plus mark each.

    The real quality issues with the Walkera multi-rotors are the ESCs the Motors and their poor customisation of the FCs. If you compare a DJI motor with a Walkera one you will spot the quality difference immediately.
     
  5. chase
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    chase Member

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    Aaahh.. don't say that, I just fixed my Scout!

    I did see the Scout motors have more magnets in them, felt like it anyway. I don't know enough about that side of things at this point to tell if ones better than the other.

    Or if one is more reliable than the other.

    I have seen Pro videographers use the Scout/Tali as their platform. And yes, one in particular, switched to DJI. But not due to reliability issues. He said it was due to being sluggish and drifting in the wind in GPS mode compared to DJI.

    That said, from what I understand, you can change the Loiter rate and it will make the Scout/Tali fly faster in GPS/IOC modes. If that's what he meant.

    Responsiveness... I don't know how to make it more responsive. Or even if it can be done.

    Now, I'm going to post one of his videos. He added the Matt Kim gimbal mod, and talked of a Flap setting change to add stability in GPS mode, and has the upgraded Dual GPS like you do.

    His bird in flight looks like someone pinned it to a point mid air.
    This guy has the most consistent smooth gentle landings I've ever seen from a Scout or Tali for that matter - zero bounce. And he had both. He also pushes the range limits on his bird.

    And it's stock in most of his videos. He lets you know that. Or in the case of the vid I'll post.. the changes he made which was only to the Flap setting.

    I'm not sure if this is pre gps upgrade, or Matt Kim gimbal mod. He says in there, but it's somewhat difficult to hear him on my cell phone...

    It's pretty impressive... take a look see.



    Personally, if I want to fly here, I'm getting wind. I'm on the shoreline so there's going to be wind. Usually no less than 10+ mph. We get the onshore and offshore winds daily. Average around 15-20+ mph winds.

    I need to make a Scout model in the TX for these type conditions. Just as you would any other bird. Possibly 3 different condition models, 0-14 mph winds, 15- 20 mph winds, and 20-30 mph. Or something along those lines.

    I realize a lot of vids showing stability of birds aren't showing windy days most times. Though there are a few that show around 20+ winds for various birds. Including one for the Scout or Tali, I can't remember.

    I want to get my Scout rock solid in high wind as well as 0 wind and everything inbetween.

    I figure the more reliable the lock is on gps... the better my chances of achieving that goal.

    And do so without spending $3k on it I might add! :D
     
    Last edited: May 4, 2016
  6. bjr981s
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    You can make the Scout more responsive just with the TX.

    Change the end point from +-100 to +-130 for rudder aileron and elevator.
     
  7. chase
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    Good to know!

    How's that setting for winding conditions versus calm conditions?
     
  8. bjr981s
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    The more agile you make it the more difficult it is to fly.

    It has more than enough power to fight the wind at 100. I tend to fly at 80. it makes it less skittery.
     
  9. chase
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    Interesting, I'll give it a try from 80-130 see how she reacts.

    I tried the FLAP setting of 100 that several were suggesting pre update. It didn't fair well at all in 17+ winds. I thought she was going to come down, especially when hit by gusts. Way too slow to correct itself. I got lucky in being able to land her that time. That flap setting might be fine for zero wind, but certainly not for the conditions I was flying in. It was good to see what she does, how she reacted aft that setting though. A definite learning experience.

    From now on, any setting changes I'll take slow. Not a big jump like I did that day (150 down to 100). I think I'll do changes in either units of 1 or 5 depending what it's for.

    I'd like to see how a Flap setting of 160 will do in the stiffer wind. Though as you stated she fairs well in wind. It's the 20-25+ mph winds she needs help in to tighten her up some. Her reaction time needs to be a little quicker but smooth at the same time do she doesn't over correct.

    It's going to take some trial and error runs in different conditions. That's why I want to set up a couple models for in the tx.
     
  10. bjr981s
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    The flap channel is the Auto Takeoff switch. It uses the extremes of the servo travel. Where did you read that it did something else?

    Changing the setting I would think would do nothing other than disable auto takeoff.
     
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