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Vision Plus and 1.2GHz Video downlink [RESULTS]

Discussion in 'Phantom 2 Vision + Discussion' started by gfo315, Apr 3, 2015.

  1. gfo315

    Joined:
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    Location:
    Rio de Janeiro, Brazil
    Hey guys!

    After one month using my Vision Plus V2.0, I realized that Wifi FPV wasn't exactly the best option for flying. There was a constant delay, and often I experienced some lag spikes. Even more - I would lose the video but not the controller for several times. It wasn't reliable at all. When flying "100% FPV", that would let me very lost.

    Not anymore! After doing some research and looking for some Gimbal/Wifi wiring diagrams (with help of some of you guys here), I found out that it's possible to split the video cable that comes from gimbal assembly, and use it with an additional downlink. And as 5.8 and 2.4 were already used, the solution was to use a 1.2GHz transmitter and receiver. Let's start with the equipment.

    - Lawmate 1.2GHz 500mw transmitter (5.5V)
    - Voltage regulator (12V to 5V)
    - Lawmate 1.2GHz receiver


    INSTALLATION PROCEDURE:
    I opened up the Phantom and removed Wifi module (watching burlbark's video), so I could have access to wiring that comes from battery to the main board. Then, I soldered the two cables from the voltage regulator, so I could get 5V and GND for video transmitter.

    Using diagrams found here and in rcgroups.com [reuploaded here], I split that last little cable from the right, which gives me "pure" video (without telemetry), and added a little extension from it.
    This way, I now had 5V, GND and Video.
    gimbal wiring.jpg wifi wiring.jpg

    Outside the Phantom, I attached the transmitter with a double-sided tape, and soldered these three cables to the transmitter's correspondents. Done!
    downlink.jpg

    IN-FLIGHT RESULTS:
    Of course, as this downlink only offers me video, I still need to use the Vision app for telemetry, ground station info and camera setup. When using CH1 on transmitter, it seemed to mess up with Wifi 2.4GHz signal, which is harmonic to 1.2. But when switching to CH2, it went stable.

    Regarding distance, I could easily go up to 500m, then I'd lose controller signal and failsafe would bring it back to me. If using SpiroNet antennas, I'm sure it won't be a big deal to go up to 2km, but this would require a antenna mod or a new decent controller.

    Even though I don't have telemetry built-in, it's definitely a good installation and will give me some more flight reliability. I'm impressed with the results.


    If you guys have any questions about equipment, installation or results, just ask here. Happy flying!
    Guido.
     
  2. clayton4115

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    great but I am getting more than 600 metre wfi with a simple antenna mod, I installed a 7db 2.4ghz antenna mod and replaced one of the stock wifi antenna built in the wifi booster. I am now losing control distance before wifi.
     
    #2 clayton4115, Apr 4, 2015
    Last edited: Apr 4, 2015
  3. flyNfrank

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    What is the main reason for doing this clean looking little mod? Are you doing it to stream live video over the internet or?
     
  4. jumanoc

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    Great finding Gfo315,
    It is a solution if your Camera-gimbal is dammaged. You can still fly with Video TX and another gimbal. And this is an easy way for sharing FPV with your friends using any monitor, tv or googles. What if you "share" video signal wire between DJI VTX and 1.2 VTX simultanueously? Does it has enough power?
    Could you post better diagram pics? No easy for reading your notes , thanks.
     
  5. gfo315

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    I wasn't satisfied with Wifi downlink at all. For me, it would have constant lag spikes and it doesn't offer the same reliability that analog FPV does. I don't know if it was because of close wifi routers or wrong channeling, but I realised that I would have better results using analog FPV.

    I thought that the video signal that comes from gimbal wouldn't have enough energy for both DJI VTX and analog VTX, but it does. I have my clean and smooth video in 1.2GHz, and even though I don't, I can still use DJI Vision app for watching the video. Instead, I swipe right and use Ground Station maps along with telemetry and stuff.

    See these images here, I've re-downloaded them with better quality. All credits to people from this thread: http://www.rcgroups.com/forums/showthread.php?t=2213815
    gimbal diagram.jpg
    See that "Video from GoPro" or "Video-IN" cable? It's the one that comes with video from the gimbal's camera (I used this one to connect to VTX). The "GND" cable right on its left is the ground cable for "pure video", even though I didn't need to connect it to the 1.2GHz VTX.
    wifi diagram.jpg
    On the Wifi module, this 1-6 section on the bottom of the unit is exactly that cable on the right that comes from the gimbal assembly. You can see that the connections are the same. The only thing I did was to weld a extension to this Video-INPUT cable (nÂș 1) that goes directly to 1.2 VTX.
     
    jumanoc likes this.