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FPV video failure at 82 metres !

Discussion in 'FPV (First Person View)' started by Flames, Nov 23, 2014.

  1. Flames

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    Hi,

    Installed a FPV combo on my P2 (HD 3D and Hero 3+)

    Flysight 400mw 5.8Ghz A/V FPV Transmitter
    DJI Innovations Phantom 2 FPV Cable & Hub
    DJI Innovations iOSD Mini
    Flysight Black Pearl 7" FPV Monitor with 5.8Ghz Receiver
    DJI anti interference board

    I'm getting the horizontal lines issue which is mentioned on this forum (power feed from P2 into Go Pro causing noise)
    HOWEVER . . . . . on it's first flight, video feed was fine up until the P2 reached 82 metres altitude (about 40 metres down range), then it broke up and finally went altogether. If I reduced altitude, the feed came back. Orientation didn't have any significant effect. Recorded video footage was unaffected, it's just the live FPV feed to the BP.
    The Tx and BP are running standard rubber duck aerials, but I was expecting more range than this, even on the standard setup. I've checked the Band and Channel settings between the BP and Tx are matched.

    Anyone else running similar spec and getting greater range, or any suggestions as to what is wrong ?

    Regards,

    Simon
     
  2. Damon

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    Range is poor with stock rubber antennas, but in your case it might be also magnified by antenna orientation. Just remember the ends of those antennas are dead zones. If you have your vtx antenna pointed down on you Phantom and your vrx antenna pointing up on your monitor, and the Phantom is pretty much up and not horizontally out and away from you. Your going to have poor reception.
     
  3. Flames

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    Hi,

    Thanks for that, I set them up as shown on the suppliers website tutorial, so the Vtx antenna is pointing down, parallel to the undercarriage leg. You reckon parallel to the ground might be better ? And what about the after market antenna, are they likely to make an improvement ?

    Regards,

    Simon
     
  4. Roseto75

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    Hi my understanding is that the stock antennas are really really poor. I am an MIT student and am really interested in rf engineering.
    I would go with proven and tested antennas like this kit http://fpvlr.com/shop/index.php?route=p ... duct_id=97

    I am going to buy this kit as soon as I find a cheap Phantom 2 , used.
     
  5. Damon

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    Location:
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    That's the antenna set I currently run. I have had it out 2700 meters with fpv.
     
  6. Damon

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    If your going to fly high above without going out very far, then yes.
     
  7. Flames

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    Hi,

    OK, will try that when the weather clears up, and I will report back.

    Regards,

    Simon
     
  8. SteveMann

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    I'm not following your geometry here - if both Tx and Rx antennas are in the same orientation, both horizontal or both vertical, then you are getting the best you can from simple linear antennas. Vertical is slightly better because it minimizes ground reflections. Circular antennas like those from fpvlr are better.
     
  9. Damon

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    In layman's term, since I'm by no means an engineer ;)

    On rubber ducks pointing sides of antennas at each other will give best range. OP had vtx down and vrx pointing up (would be best if flying low and away) OP was flying close but high. Basically pointing ends of antenna at each other, though not absolutely directly over head.

    I could only get around 80 meters with stock ducks, then using mushrooms maybe 200. I added cheap patch to dual diversity monitor and extended to 300 meters. Ultimately switching all that out with fpvlr kit with pinwheels & helical and get 2700 meters without issues.
     
  10. Flames

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    Damon,

    Is the direction of those antenna that you have critical, or do you get that range whatever way they point ? (i.e. horizontal, or pointing down) I'm looking for a clean option if possible, but am happy to compromise if it gets me better range on the video.

    Regards,

    Simon
     
  11. lake_flyer

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    80 meters is what I get when I use no Rx antenna at all. With standard rubber antenna's I get 1300m on my Fatshark 250 mW.

    Maybe one of the rubber ducks has a bad connector or is broken internally. It should be way more than a few hundred meters. Straight over head you will get stripes and interference but you ain't supposed to loose all signal at once. If you turn the RX antenna a bit into horizontal you should get a decent feed again.

    I tried a antenna with female connector where it should be male and got the same problem as you (OP) has.