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Old Nov 25, 2012, 04:45 PM
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Possible dual vTx setup on plane, comments please

So i was out flying today with my goggles and i ran into a slight problem, which i'm sure many of you have, so i'll describe it.

I have a bixler with a 500mw 5.8ghz tx, and a cloverleaf, on my goggles i'm using a skew planar wheel antenna.

When i fly, i tend not to go out very far, I just like to get altitude, and a nice view of the area, so my LOS angle to the plane tends to be past 45 degrees (vertical), today it hit close to 70 degrees, as i got up to over 600m. Of course at this point i'm starting to hit the dead zones in the antennae, since they are both situated vertically.

Now i dealt with this by flying out a little further, and banking the plane to re-establish my video signal (i never lost it for more than a second, but i got a lot of static other times when i got that high).

My question is this, i have 2 possible ways of dealing with this:

1. use the existing setup but point the antennae sideways, so my null axis would be horizontal, not vertical, and as i gain altitude (yet not straying far from field) my signal should stay in the sweet spot.

2. Setup 2 video transmitters on the plane, on different channels (as far apart as i can get on an 8 channel 5.8ghz), one with a cloverleaf oriented vertically, the other horizontally. The ground station would have 2 receivers, and each would be paired to the appropriate video tx with SPWs (one video tx + one receiver would be on same channel with vertically oriented antennas, for horizontal distance, the other pair on another channel with horizontally oriented antennae, for vertical distance). I'd hook in the receivers through a diversity (i have one spare) and feed the video in to the goggles.

Thoughts? I'm not looking for super long ranges, just the ability to be as omni as possible without losing signal and soiling myself when my plane is 600m above me.

I curious if anyone has tried this, or if there is some limiting factor that i am completely missing. This would be mounted on a super sky surfer.
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Old Nov 25, 2012, 11:39 PM
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I would try a small helix pointed in the general direction of your plane (can you find a 3-3.5 turn?). Use diversity and see how it works out. I rarely fly in this zone but imagine if I spent most of my time there it (static) would get annoying.

I would definitely try putting the antenna on its side before buying anything though.

I wish I had something useful to tell you about using 2 vtx, but unfortunately I have no clue...
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Old Nov 26, 2012, 12:10 PM
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Originally Posted by chemnut842 View Post
I would try a small helix pointed in the general direction of your plane (can you find a 3-3.5 turn?). Use diversity and see how it works out. I rarely fly in this zone but imagine if I spent most of my time there it (static) would get annoying.

I would definitely try putting the antenna on its side before buying anything though.

I wish I had something useful to tell you about using 2 vtx, but unfortunately I have no clue...
I may try the antennae on the side first since i'm most going to be circling up and over me as i gain altitude, i have enough parts coming in that i'll be able to try what i suggested, though a diversity with SPW + the helix pointed straight up might work too, i'll post back once i try it anyways.

I don't have a working antenna tracker yet, that would be the ideal solution of course
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Old Nov 26, 2012, 12:18 PM
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You don't need two vTxs, just two antennas is enough. I'm not sure anyone ever tried to mount a dual antenna on a vTx that normally only supports one though.
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Old Nov 26, 2012, 01:10 PM
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Sircana tested a dual vtx setup using left and right polarised cloverleafs, worked quite nicely apparently.
http://fpvlab.com/forums/showthread....ultimate+video
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Old Nov 26, 2012, 01:16 PM
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Whoa, that's a lot of work. Turn your antennas sideways, they are cp so they won't be out of phase just out of the null zone. DO IT!
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Old Nov 26, 2012, 02:28 PM
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Originally Posted by mich75 View Post
Sircana tested a dual vtx setup using left and right polarised cloverleafs, worked quite nicely apparently.
http://fpvlab.com/forums/showthread....ultimate+video
yeah i just saw that thanks, i think for now i'll keep it simple for the next flight and just flip the antennas sideways, because it'll take me all of 1 minute to do =)

I'll keep the fancy stuff that leads to tears for next month possibly
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