DIY FPV twin receiver diversity controller

by Rixx | May 26, 2012 | (14) Posted in Projects

 

Hey, hi. I got this idea from Bruce at rcmodelreviews.com and built the controller with arduino.

I was flying FPV with helical only, and I was getting some dropouts if I flew right above, or doing circles around me and ground station, preparing for landing. I could have just swapped helical for skew planar wheel, but I'd limit my range then. So why not use both at the same time? Pieces I used to put this together

- arduino pro mini (Duino - clone from ebay)
- Turnigy UBEC
- relay
- power transistor
- two 5.8GHz receiver modules
- small 12v fan
- few passive parts (resistors, diode, capacitors, connectors)
- stripboard

 

Idea is simple: watch which receiver has higher RSSI (relative signal strength indicator), and switch that video signal out to display. In practice, I found out that modules are not perfectly identical, and put out different levels of RSSI. So arduino first does some calibration at the startup to get minimal and maximal RSSI when I turn on video Tx, and then does scaling to percentage prior to comparation. Nothing fancy, arduino is pretty much bored with about 10% memory used for this poject :).Some more pics for inspiration, enjoy!

 

 

3 prong connector in the middle is mini-XLR, carries power, ground and video signal through shielded cable to my LCD display. Rx modules and UBEC heat up a little, and black box in the sun wouldn't help them either, so I hotglued there small 12V fan from old computer, and drilled vents to the bottom part of box.

 

 Guts!

 

mild  spaghetti


COMMENTS

Danger Mouse on May 29, 2012
Hi Rixx

Will you be doing a more detailed build article?

Kind Regards

DM
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Rixx on May 29, 2012
Hi. Yes, I'm preparing another article, will be up in couple of days.
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Danger Mouse on June 3, 2012
Hey Rixx

I'm really looking forward to your follow up article. I own two RC305 RX units and I'm keen to integrate your diversity controller with these. Will you be offering an explanation of how the circuit works? I understand the basics but I'd love to understand why you have selected particular parts e.g. capacitors?

Kind Regards

DM
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Rixx on June 4, 2012
Hey, hi. Ok, I'll explain it closer if you wish. And also a possibility to use RC305's whole, in one piece without taking modules out.
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Danger Mouse on June 4, 2012
Sounds fantastic!
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Rixx on August 5, 2012
Hey, hi guys. Sorry for missing second part of the build, but I'm busy with some family things since I made this first article. Sadly, I won't be able to make another article any time soon. But I try to be helpful at rcgroups thread, dedicated to this diversity system.

http://www.rcgroups.com/forums/showthread.php?t=1661980
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TeamEZephyr on August 5, 2012
Hey man nice diversity controller but what code did you use to load onto the arduino could you sent me a link or tell me how it's called

Thank you,
TeamEZephyr
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mena142 on September 19, 2012
Great idea! Cheap and inventive. The only downside I see it that it will decide on the signal quality and not the image quality. The signal could be strong, but with a lot of multipathing.
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Rixx on September 20, 2012
Also, simple and without exotic parts. Can't get any simpler than switching by RSSI. Multipahing? That's why I use CPL.
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L33n0x on May 29, 2012
Hi Rixx!

Can you tell me what is the final cost of your montage ? I really like your build but your system is better (or equivalent) than this one http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=11656 ?
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Rixx on May 29, 2012
Well, this cannot compete with eagle eyes. That incorporates antenna tracking and diversity and telemetry, etc etc. My project only switches video output to the display from receiver with stronger signal. Nothing more and nothing less. Total cost? Arduino clone about 10$, UBEC 5$, relay 3$, receiver modules 15$ x2, UHF connectors 5$, stripboards + other small items ~ 5$... something under 60? ( but Eagle eyes has no receivers, so substract 30$ and you are at about 30$ for this project)
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colorex on July 10, 2012
Cool how you "implanted" that UBEC :P
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schraut5 on May 29, 2012
Very nice! What kind of range are you getting with this system?
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Rixx on May 29, 2012
Flew it today for the first time. My Tx cloverleaf must be broken or something, because I got dropouts at about 400-600 meters, what was never a problem before (I flew with helix only, aimed by a friend :) )So I cannot say. Range depends on antennas, make/buy good ones and you're okay.
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schraut5 on June 3, 2012
Hmm. That is weird. I'd be interested to see what kind of range you get with all of the kinks worked out. I easily make it to 1000m with my homemade cloverleaf/skew-planar on 5.8.
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Rixx on June 3, 2012
I need to build VSWR meter I guess :D
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Rubnorris on September 19, 2012
Dude! THis is soooooo EPIC on it's compact size. Love it!
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Rixx on September 20, 2012
Haha, thanks! Since the article, I added discrete twin video amp, so board is pretty crammed now. But still fits in the box :P
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mattplaneflyer on February 24, 2013
You definitly look like you now what your doing.
Great job!
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planecrazy03 on February 1, 2014
so... can you put up some schmatics? or some good stuff so we can build it too??
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DIY FPV twin receiver diversity controller