2 x 1,3 ghz video downlink on the same bird

Discussion in 'Video Assist & Video Accessories' started by Lauri Hakala, Jun 14, 2013.

  1. Lauri Hakala

    Lauri Hakala Member

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    Hello all,

    We are about to start filming golf courses for our local golf club. It has to be a single shot per lane (flying height about 35ft) so we'll eventually loose the line of sight. The longest courses are about 500m (1600ft). I was actually able to fly one short course with only line of sight but fast realized that I would need FPV system to do it comfortably. I use 1,3ghz dowlink for the camera operator and would like to use another 1,3ghz system for FPV purpose - is this possible without interference? I need the obstacle penetration 1,3ghz system offers because there are lots of trees on the courses. I have 8 channels on my downlink so I could just choose two channels furthest away from each other, would that work?

    I use these antennas for my downlink at the moment, should I get these same ones for FPV also?
    http://www.readymaderc.com/store/index.php?main_page=product_info&cPath=11_45_52_100&products_id=552

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    Most of the courses are almost straight lines and I think that the range should not be a problem. Maybe on the curved ones I could leave the copter in the start and fly from the midpoint for better visibility? Just have to go and test the range of my current setup before buying anything. Thanks!
     
  2. Scott Stemm

    Scott Stemm Member

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    I would suggest to stand in the middle at the dogleg and fly from there. You would have visual on both legs
     
  3. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Did you add the heat-shrink to the transmitter? I'd be concerned that it's going to get way too hot with that heatshrink on it....

    Andy.
     
  4. Lauri Hakala

    Lauri Hakala Member

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    Ohh the heat-shrink was already on when purchased. It indeed gets quite warm when in use but haven't had any problems with it. Would gladly change to dual 5.8ghz system (camera OP + FPV) if that makes any sense.
     
  5. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Oh....that's the first time I've seen a Tx with the heatshrink on it. Well, let's make the assumption that whoever added it knew what they were doing? Right??

    You can certainly use two Tx on the 1.2/1.3 Ghz frequencies -- I'd "skip" one channel -- so if one Tx is on Channel 1, then set the second to Channel #3. It certainly won't do any harm and the quality of the video you receive will be the final determinant of whether you need to move the frequencies even further apart.

    I would be sure to use a low-pass filter on each Tx, though as you're radiating quite a lot of power and the first harmonics of the frequencies will be around 2.4 Ghz which is the same frequency as you're using for the flight control transmitter.
    Here's the type of filter I'm talking about: http://www.dpcav.com/xcart/Low-Pass-Antenna-Filter-for-1.2GHz-1.3GHz-TX.html

    Andy.
     
  6. Lauri Hakala

    Lauri Hakala Member

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    Thanks Andy for clearing things up!

    Another question, how are you guys powering your FPV -transmitter and camera? I wouldn't want to use an additional battery because of the added weight and hassle of charging all the different batteries. I fly with two 4s 6000mah batteries in parallel (EC5 connectors). I heard that one could power the FPV -setup directly from the balance plug of the flight pack? Is this possible and does it matter that I use two packs in parallel? Any other clever and simple tricks to power FPV? I'm gonna use this tx for fpv: http://www.globe-flight.de/Kabel-Power-Molex-ImmersionRC_1 Have no clue where to get a power cable to fit JST-XH balance plug.
     
  7. Gary Haynes

    Gary Haynes Administrator
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    Lauri I run a separate battery. It looks like you may be using a 2 axis setup. I use a small 3S 2500 Turnigy and put it next to the main batteries. It runs everything FPV. FPV Camera, TX, FF HDMI. Found I get better video that way.
     
  8. Lauri Hakala

    Lauri Hakala Member

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    Actually it's a 3 axis setup, but yeah hard to see from that picture. So I would much prefer to use the flight packs for power if there's nothing wrong doing it, keeping it simple you know :) You think I'll get some noise or interference if I don't have a separate power source for fpv? My video downlink on the gimbal already has its own little 3s battery.
     
  9. Gary Haynes

    Gary Haynes Administrator
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    Haven't seen anyone use the flight packs since the camera gimbal deck rotates. All that I have seen is using a separate battery to power things on the gimbal deck. Sometimes 2 batteries, one for gimbal servos and Radians and second for video due to the electrical noise from the servos.

    Only way to really know is give it a try. I got noise from the motors when I did it. Maybe put in a line filter like the ones sold by DPV.
     

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