The $25 FPV Diversity Controller

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The $25 FPV Diversity Controller

Postby ChrisFredriksson » Tue Feb 24, 2015 3:58 pm

Hey everyone,
I just recently found the video on the RC Model Reviews Youtube channel and I love all things electronics, so I could probably somehow reverse engineer the board from the video and get "similar" results of function, but I was wondering if anyone knows, or if Bruce happen to read this thread, is there any more information available anywhere regarding this project?

Is there a schematic available somewhere?
Is it still the CD4066 that is used together with the PIC?
Is the RSSI signal read through an A/D channel on the PIC? I suppose it is a PWM signal?
Is there any source code available?

Surely none of this is needed to create a brand new project, but it would perhaps be a good place to start, to not reinvent the wheel right? :)


Also, as this is my first post here, I'd also like to say Thank you! to Bruce if he happens to read this thread, a big Thank you! for all your work with the channel and all the problems with the officials banning you from flying and all that.. Would probably take the power out of most people..! Keep up the great work Bruce! :)
ChrisFredriksson
 
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Re: The $25 FPV Diversity Controller

Postby Magilla » Tue Jan 12, 2016 2:37 am

I'm also interested in the idea of the diversity Rx.

Re: RSSI, Bruce also did a video on a $1.29 diversity system. The RSSI signal was just a simple voltage output - more voltage = better signal, so easy enough to do voltage comparisons with opamps.

The $1.29 video: https://www.youtube.com/watch?v=4yDfRrsH0WM

Unfortunately both of those projects seem to have died (at least the $1.29 project got to the point where it was usable and copyable from the video instructions).

The PIC on the $25 version was just being used as a 4-way voltage comparator, as far as I can tell.

I don't know the exact reason that the project died, but it may be that he had problems with switching cleanly between video sources. If that is the case, I think the problem is with video frame sync. If the video sources aren't perfectly in sync, the screen electronics have to realign with the new video input, which could cause the flickering and black lines across the screen. It could also be caused by lag in the switching process (IE an area of no signal or double signal in the switching process).

Fixing frame sync (something video broadcasters have to do to avoid exactly this problem) seems to involve a unit that costs $1000+, plus you also need a sync clock on top of that. Fixing a signal gap or overlay could be fixed by fading/mixing the signals rather than attempting to hard switch, but the frames would probably have to be in sync first for that to be possible.

The easier fix for frame sync may be to set up master/slave clocking on the video Rx units themselves, if (1) they do reframe/reclock the video signal onboard and (2) there is a clock/sync pin that can be cut on the slave boards and wired to the clock on the master board.

I'm no electronics engineer, though. This is speculation.

Edit: Heh, I missed that this thread was a year old. The $1.29 project was posted a month after you posted that.

Edit 2: You can get a Skyzone dual-channel diversity Rx here: http://www.hobbyking.com/hobbyking/stor ... ables.html for about $70.
Magilla
 
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