Low flying a quad with another one above as a video relay station? - RC Groups
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Sep 16, 2010, 08:27 AM
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Low flying a quad with another one above as a video relay station?

Hi, reading like crazy in these forums and trying to learn. The quality of all-round knowledge is definitely the highest in this thread.. amazing.

Could anyone tell me if this idea is feasable or not?

If you use a quad for FPV you better keep flying low. The bottleneck on distance seems to be the video connection because you will lose the Line of Sight easily when going <3m.

Just want to understand if it would be possible to have another quad flying high above, receiving the video signal and transmitting it (on another freq?) to the base. The mikrokopter has a follow-me feature that could keep another mikrokopter flying above at say 100 meter at all time. So there is always LOS as long as you don't enter anywhere.. Demonstrated here:

Would that work? Could it even relay the r/c signal? Receive PPM and send it on to the low quad?

If I understand this then I will have read enough for a while! Until my fatshark stuff comes in.. I am not worried about it being risky or expensive, it's more the theory that I would like to understand.
Last edited by kennyfly; Sep 16, 2010 at 08:34 AM.
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Sep 16, 2010, 09:33 AM
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motorhead's Avatar
Should work. On the relay station I would have a receiver on 900mhz and then transmit to the ground on 1.3mhz. You do not have to use these frequencies but I think it would be best to have good separation.
Sep 16, 2010, 09:41 AM
Registered User
There would be a lot of frequencies in the air..

Is there a way to relay the r/c signal, can that be done? I could imagine feeding a ppm signal to another transmitter that is bound to the receiver on the low flying quad? Might that all be on 2.4ghz as long as it is the FHSS etc?
Sep 16, 2010, 09:44 AM
The Flying Circus
ommadawn's Avatar
I reckon having another quad as a relay is overkill. How about using a balloon, blimp type of thing as a relay station. No one needs to be flying it.
Sep 16, 2010, 09:47 AM
What was that...
StealthWorkx's Avatar
Had the same sort of idea with my Zephyr and Easystar,
On the Easystar ther'd be a 2.4ghz VRX that then re-transmits the Zephyrs signal.
quality may be not so good but as long as it's flyable it should work. I wouldn't relay the RC link as im on Scherrer UHF and on the high power setting that should be ok.
I was think of having the relay link on say 1.2ghz and the other 2 links (zeph and easystar primary FPV link) on 2.4ghz but that was only as i had a spare 1.2 unit.
Id use it just for a bit of Fun, might be cool to give it a go some time
Sep 16, 2010, 11:22 AM
Registered User
Have a look at this video Ommadawn, nobody is flying the high quad, it just follows the first one at a fixed height, connected by a radio link from the low quad that sends the GPS coordinates to the high quad.

A blimp wouldn't be able to keep up with the low quad. You want to be straight above as much as possible so the low quad can get into narrow streets and behind any number of walls, houses, mountains..

I am sure even the Sherrer UHF would get in trouble after lots of walls, so it could benefit from a relay up above. Then use sherrer's system to link the high quad to the base.

What remains, can you relay the PPM signal? Can a sherrer receiver bind to two transmitters, or would they only bother each other, so you would need two r/c frequencies.

It should be able to put the quad FPV'ing bottleneck back to the battery, not the LOS...
Sep 16, 2010, 12:17 PM
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Hugeone's Avatar
The Scherrer UHF receiver output the PPM train on ch12, so one could plug in a second Tx unit to relay signal. Since each one have different code and don't interfere, I believe it will work.

Sep 16, 2010, 02:20 PM
Registered User
But to be safe you would want the low quad to listen to the base station as well as the high flying quad, so you wouldn't be totally dependent on the high flying one. So they would transmit the same r/c signal, with the same 'binding code'. The high flying quad would give redundancy at the edge of the base's reach.

Would that be possible with the UHF system or am I misunderstanding something?
Last edited by kennyfly; Sep 16, 2010 at 04:49 PM.
Sep 16, 2010, 04:32 PM
Registered User
Hugeone's Avatar
That won't be possible, two Tx with the same Id code will produce serious multipath issue (two signal not coming at the same time to the receiver.)

Sep 22, 2010, 07:55 AM
Registered User
Well there is a ready-made video solution:
Sep 22, 2010, 08:12 AM
Suspended Account
You can get into trouble real quick flying a Quad low FPV. They can fly in directions that the camera can't see. So it is real easy to fly into something.

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