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P2 losing video signal easily

Discussion in 'Phantom 2 Discussion' started by johan, Apr 26, 2015.

  1. johan

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    Ok new question for the group. The video transmission reliability of my PS in a word, sucks. We've got lots of woods at our place. But there's about 100 yards of open space from the back deck out to the tree line. Its maybe 30 or 40 yards wide. If I fly to the rear tree line, I lose video. That's about 300' give or take. And its not like I'm flying in the middle of a city. We've got very little RFI out here.

    The bird had a Boscam 600mw transmitter on it when I bought it. The previous owner put a cloverleaf antenna on it. The receiver is a Boscam LCD5802. It had stock antenna when I bought it. So my first guess was better antenna for the receiver. I bought a pair of Fatshark cloverleaf deals for it. No difference. In fact they might be a bit worse because at least with the stock antenna I could sometimes play with their orientation and get a bit of signal on my screen for a few seconds so I could at least figure out which way the bird was pointing.

    So next I figure maybe the transmitter got powered up without an antenna on it and fried itself. So I ordered a new Boscam 600mw transmitter. The results are about the same.

    This morning I tried a couple of flights in the back yard to see if I could fly just off the screen. I got the bird in the air and took it up over top of the house. Then climbed above the tree line and flew slow around the property. At about 60 meters up and maybe 30 meters out from where I was standing, I had a black screen. I the bird was above the trees but I could clearly see it pretty much the entire time. Every now and then, the video would flicker on but for the most part, the screen was black and unusable.

    So what's the solution? I see people reporting good video reception out to a mile all the time. How are they doing it? I'd be happy with 1/2 a mile. Hell a reliable 1/4 mile would be an improvement at this point.
     
  2. noiseboy72

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    I would replace the cloverleaf on the TX with one you know is correct for your new RX antennae. There are various types - both in terms of the connection, but also the polarisation direction - Left Hand or Right Hand.

    The cloverleaf antennae should point directly down on the quadcopter - hanging underneath so far as is possible, with the ones on the RX should be nice and flat.

    Cloverleaf do not extend range contrary to popular belief, but reduce fade when turning. For more range, a helical or patch will show an improvement. I easily get 300m with a similar set up to you, so it should not take much to improve things.
     
  3. johan

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    Yeah that's just it. I don't know which antenna are correct. I don't know squat about antennas.
     
  4. Hughie

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    OK, you may not do, that's fine. But do you know which ones you have at the moment. If you bought them do you have links to them so the polarity and type can be checked ? Some pictures of your setup may help too.
     
  5. TeamYankee

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    Yes..pictures... :)
    If you have the wrong "hand" polarization then you would have the symptoms you are seeing. Putting a "rubber duck" on the receiver would improve the signal though.. try that first.
     
  6. johan

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    I don't have any literature on the transmitter antenna, but it looks exactly the one that comes with this version of the transmitter.
    http://www.amazon.com/Boscam-TS832-...TF8&qid=1430146024&sr=8-4&keywords=boscam+832

    And these are what I ordered for the reciever:
    http://www.amazon.com/gp/product/B00KAOT4LM/ref=oh_aui_detailpage_o04_s00?ie=UTF8&psc=1

    I still have the rubber ducks for both the transmitter and receiver. I haven't done any A B experiments with flying the same path and then switching them out but I could probably try that if the weather allows and see if the rubber ducks actually perform better at this point. I'll also take some photos when I get home and put them up.
     
  7. johan

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    Ok I did a bit of experimenting this evening and shot some video of it. I won't bother posting it because there is nothing definitive in it. The experiment was productive though because it taught me something I didn't realize before. I knew that good video reception requires line of sight. What I didn't really realize is that line of sight doesn't mean you can see it. Its becoming apparent to me that line of sight means absolutely nothing but air between the transmitter and receiver.

    We've got lots of woods on the property. But because the leaves aren't really out yet, I can fly quite a ways above the tree tops and still be able to see the drone and orient it. But watching carefully during my experiments this evening I realized that the moment any part of a tree gets between the transmitter and receiver, the video feed goes south fast.

    I still want to do more experimenting because I know I've flown in wide open areas where there was absolutely nothing but air in between and has the video flake out at relatively close distances. So next time I'll go to a wide open area and fly with all the various antenna combinations.

    But first a couple more questions. My receiver has a video out jack. Is there a relatively cheap and easy way to capture a feed from that in the field? When I flew tonight I just took a spare gopro and mounted it over the receiver screen. It works but there is lots of reflection off the screen which makes it hard to see in the video at times.

    Next, assuming my deduction is correct that these video transmitters tend to not do well with any part of a tree between it and the receiver, does the system used in say, the vision or inspire or even the phantom 3 do any better in this respect?
     
  8. TeamYankee

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    Hmm.. LOS is tricky.. there's line of site and "near" line of site..

    It's all to do with the Fresnel zones... http://www.proxim.com/products/know...ions/calculations-fresnel-clearance-zone#feet

    If any object encroaches into the zone then signal loss will occur. Especially at higher frequencies where the signal strength is readily absorbed by water, ie: fresh leaves etc.

    Check out the system operational margin calculations.. just plug in the antenna db info and that will give you the radio link losses in air... http://www.proxim.com/products/know...ions/calculations-system-operating-margin-som
     
    #8 TeamYankee, Apr 29, 2015
    Last edited: Apr 29, 2015