FPV Camera signal showing strong interference from Servo signals

Discussion in 'Scratchbuilding!' started by mastermalpass086, Jan 10, 2019.

  1. mastermalpass086

    mastermalpass086 Ace Pilot

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    So, the Dh. 82, still yet to fly, has been fitted with an FPV set up. I am very good at crashing into trees, so I don't want to rely on my depth perception when making my approach to landing. However, what I have set up is unusable due to interference when the servos are doing work.



    So a few extra notes on the video. The 'White bars' I mentioned, appearing with servo use before the video system gets a chance to heat up, shows one thick white bar about a 5th of the screen's height flicker down the screen at such a speed you can pretty much see through it, however, as I push the servos further, the strength of their interference goes up and so steeper moves, especially when two servos are working at the same time, produce the same effects you see here with subtle inputs.

    Also, I'm wrong about the camera's power supply. It's not tapping into the BEC. The camera is tapped into the transmitter's cables that go into the Radio Tx's Aux port. Both the camera's Earth leads are soldered to the same black wire of the transmitter's and the yellow audio lead is a dead-end with tape keeping it from touching anything.

    I have read about voltage regulators and capacitors (the quadcop guys use this to fix interference from ESCs). I was under the assumption that a BEC-supplied Radio Tx would have good power control, but should I still add capacitors and regulators to my wiring?

    Thanks in advance for the tips!
     
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  2. bogusbandit56

    bogusbandit56 Top Gun

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    I don`t have a clue but maybe this will help.:)
    https://www.rcgroups.com/forums/showthread.php?1612507-Static-in-video-when-servo-moves
     
  3. mastermalpass086

    mastermalpass086 Ace Pilot

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    Thanks BB, but it's a dead-end. The thread doesn't confirm if the last thing works:

    upload_2019-1-11_8-1-57.png

    All these guys are talking about the use of an OSD (most forum threads I find about this are) - in fact, at one point he fixes the issue by taking the OSD out of the circuit and the thread continues because he wants to keep it and solve the interference. My set up has no OSD or Telemetry equipment. It's all raw.

    However these guys do talk a lot about grounding. I will have a look into potential ground loops, but I'm really not sure where my solution lies... Besides the Rx, what can serve as a ground in a plane made entirely of foam, wood and nylon?
     
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  4. bogusbandit56

    bogusbandit56 Top Gun

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    Sorry Dude , I haven`t a clue what you`re talking about, the closest I`ve got to aerial photography is when I stick my mobius on a plane.
    I would have thought the ferite rings would have helped.
    I think you will have to change the FPV frequency.
    Give Tom Monton or Malukk a shout , I think they do FPV with their Explorers.
     
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  5. FED50H

    FED50H Administrator

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    I have powered my camera fpv (runcams) from an extra channel on the airplane receiver...haven't seen that type of interference at all....maybe try powering it directly from your battery pack or from the bec....you need to isolate the power from the control circuits...it all becomes tedious to keep soldering and adding...but I think a "clean" power supply to your fpv gear will help ...or even try a separate small battery to test, before cutting and splicing
     
  6. I agree with Fed50h here on trying the things first. But typically a highly recommended solution for these issues is to use a low pass IC filter and/or low esr filters to reduce the noise in fpv signals. You can read more about it on Oscar Liang’s articles which are very informative in general when it comes to fpv:

    https://oscarliang.com/lc-filter-fpv/

    Hope this helps
     
  7. TomMonton

    TomMonton Administrator

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    I think they have it right. Isolate your vtx power supply.

    I never trusted feeding the vtx using power provided off the ESC feeding radio and servos. With most 2s or 3s systems ...you can just plug you vtx directly to the battery.

    Extreme measures would be used a separate battery

    Antennas should be at least 1 wave length apart but that is not always possible. Do try to provide as much isolation there as well. Primarily be sure to mount tx and radio antenna at different horizontal planes where ever possible.
     
    Last edited: Jan 11, 2019
  8. mastermalpass086

    mastermalpass086 Ace Pilot

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    Thanks guys! I have ordered an LC Filter and will re-wire the camera+VTx power supply to the battery through it.

    Hopefully this will solve my issue. Now you guys have mentioned it, it almost seems obvious now that power supply from the RTx would fluctuate when using servos also supplied by the RTx! I was thinking the Ailerons gave the worst interference for having their leads running under both the camera and VTx while the other servos were behind it, but now I'm thinking it might just be worse purely because there are two servos running off that channel, giving twice the interference. More you know!
     
  9. bogusbandit56

    bogusbandit56 Top Gun

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    Hi,
    I will put some diagrams on this thread regarding wing joining the old fashioned way for the Hurricane so we don`t go off topic on the AN2 thread.:)
     

    Attached Files:

  10. mastermalpass086

    mastermalpass086 Ace Pilot

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    Thank you BB! More and more questions are popping up in my head about this project, and not wanting to start a thread for every single one I was wondering how I could best go about asking - I think this thread may become my 'Engineering & Development techniques' discussion for the time being.

    I was laying in bed last night, remembered Quorneng's image of the ESC Heat-sink poking out under front fuselage and a bunch of questions regarding how I will manage the cooling system on the Hurricane popped into my head!
     
  11. bogusbandit56

    bogusbandit56 Top Gun

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    My answer to the heat problem is go big on the motor and esc and fly at quarter to half throttle.
    If your doing the tropical version you can use the filter intake for cooling.
    What size Hurricane are going to build?
    We built a 42 inch P. 40 and I never had any cooling problems.
     
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  12. mastermalpass086

    mastermalpass086 Ace Pilot

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    That's a nice looking flyer!

    The Hurricane is scaled around a 9inch prop, so it's going to be a little on the small side at roughly 800mm/31inch wingspan. Motor's gonna be big I guess, haven't got those parts in yet. I figured an air-intake via the front air-filter with an output through the radiator should keep the air churning enough in the nose area, with ESC and BEC taking a place on the side-wall each. A bit like the tiger moth but the tiger moth has a direct airflow over those pieces:

    upload_2019-1-13_14-26-21.png

    The big question is how I cool the VTx without leaving a window open on the canopy or cutting a big ugly hole in the rear fuselage.
     
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  13. bogusbandit56

    bogusbandit56 Top Gun

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    I would definitely go bigger than 900 mm. War birds can be tricky but small warbirds:confused: I would n`t consider going this small and doing an ultra scale job AND FPV.
    Bigger is so much easier to build and fly.:)
     
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  14. bogusbandit56

    bogusbandit56 Top Gun

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    Personally I would break this project into two builds.
    1 a scale Hurricane line of sight plane and
    2 a stable dedicated high performance FPV plane.
    I built a simple pusher model from foamboard and depron that was designed for FPV called the Tchuk.
     
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  15. mastermalpass086

    mastermalpass086 Ace Pilot

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    Hmm... I've got some 11-inch props coming in the post, let's scale it up to that...

    upload_2019-1-13_15-14-41.png

    Well that certainly makes things more spacious. Wingspan will now be 970mm/37.7inches... The wheels I have perfectly match the scale now as well!

    ... I hope Hobbyking do refunds though, I bought six of these 9-inchers. The blenheim was gonna use them too!

    upload_2019-1-13_15-17-34.png

    Note; the FPV was a just in-case. Seeing as the Dh.82 wasn't originally meant to have it, but there are a lot of trees where I fly.
     
  16. mastermalpass086

    mastermalpass086 Ace Pilot

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    Actually, on second thoughts, refunding them seems like too much effort considering what they cost... Maybe I'll make a beast-mode parkjet with them or something.

    upload_2019-1-13_15-21-58.png
     
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  17. bogusbandit56

    bogusbandit56 Top Gun

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    It`s their bloody shipping cost that cost the money, I think a lot of people are peed off with them and their so called customer service( none existent).
    You might as well hang on to those props, they will be useful for later twin projects.
    I was going to say something about taking cooling from the central oil cooler or supercharger cooler.
    Unless you are an actual paid up member of the Scale Police, don`t get to hung up on prop sizes. Who can see them at 100 feet doing 1200rpm? :)
     
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  18. mastermalpass086

    mastermalpass086 Ace Pilot

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    Tru dat, I could see how well she flies with a 9-incher. Still, scaled to 11 inches - I got it wrong first - notice the blue line representing the prop goes further than that on the blueprint, I scaled it up a bit more to match - the wingspan is now 1016mm/40inches. Should build and fly a bit more comfortably now! :)
     
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  19. bogusbandit56

    bogusbandit56 Top Gun

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    If you had gone for an early mk1 you could have used a cheap 11 inch slow fly prop:)
    As a matter of interest which motor will you be fitting.
     
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  20. mastermalpass086

    mastermalpass086 Ace Pilot

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    Wheels and prop are the only parts I already have for this project. The illustrated motor and ESC sizes are based on what the Su-34 is carrying:

    upload_2019-1-13_16-30-43.png

    Got these based on the recommended parts in the RC Powers Master Parts list:

    upload_2019-1-13_16-40-58.png

    Fitted with a 4-bladed 6incher, the Su-34 cruises between 1/3-1/2 throttle, and can pull a vertical zoom at Max. It was a bit under-powered on the two-blader; 2/3 throttle was the minimum cruising speed and high-alpha was easy to get stuck in. With a 3-blade 11-incher, I imagine this power system will give a nice half-way performance between the Su-34's two extremes.
     
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