By putting the OSD information in the video on the ground it will remain on the display if the video from the transmitter is interrupted. Also when the Tx signal gets weak the OSD info will remain clear.

 

How would you go about getting the Mavlink data out of the ground based Xbee to the MimimOSD?

Right now I have a XtreamBee USB adapter on the ground. Can I just change that to a FTDI board (same one as airborne), parallel the data between the MimimOSD and a FTDI to USB cable? Will Tx/Rx lines need to be swapped? The USB cable would then plug into the computer running the Mission Planner.

 

Any help is appreciated.

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You will have a hard time getting much help on this, but I am doing the same thing. I am currently stuck on problem where it will not overlay video and osd together, but I can get one or the other working and I think this problem will eventually be solvable.

Anyway, what I have done is to use an xstreambee adapter on the ground, with the 900mhz xbee. I soldered extra long pins to it so I can connect an FTDI to USB cable to it. This provides power and allows me use the mission planner in parallel.

With the extra long pins I can plug jumpers to the other side of the pins to take 5v, ground and data out to minimosd.

I have soldered the pads on the minimosd so it is all powered from the USB/FTDI cable (5v). I created some rc connectors to RCA plugs so I can connect my rx and goggles to the minimosd.

This is where I am currently having problems. If I plug in the goggles only on the video output side, I can see the OSD perfectly on a black background. All the data is flowing through just fine. When I plug in the Rx to the minimosd video input I lose the OSD and only get video.

Thats where I am at right now. I'm sure is solvable, just need to keep plugging away. Hardware is not my area of expertise, but looking at some other forums, it could be the voltage i am supplying to the max7456 chip (min 4.75v, but my usb only puts out 4.85, so could be cutting it fine) or it could be something about how the rx and goggles are grouded (needs to share the same ground) or it could be something else. I hope one of the gurus around here might be able to help.

Regards

James

I've been playing round with this a bit more this afternoon and have made some more discoveries. Basically, the OSD chip works, the problem is somethign to do with my video Rx. If I put the output from a DVD player into the MinimOSD, I can overlay flight information from my plane just fine. However, when I plug into the output from my Immersion RC Duo5800v2 receiver instead of the DVD player, I only get video and no OSD.

 

There must be something different about what my Rx is outputting vs a normal PAL DVD player. I have a PAL video camera on the plane, but I don't know what the Rx is doing with the video before outputting. I need to keep investigating.

 

So it's fine if I want to watch Top Gun under my OSD, but useless for actual video from my plane :)

 

 

Regards

James

 

Thanks James. This is the information I am looking for.

So it seems you are using a FTDI adapter board on the ground where I am now using a USB adapter board. And then you are using a FTDI/USB cable to the mission planner. Thats what I was thinking. Then all I really need to do is buy another FTDI adapter board for my ground based Xbee.

 

I can't shed much light on your problem. Make sure all your components are set to PAL and one of them is not NTSC. Make sure the default format is selected on the OSD via the solder pad so it does not auto-select.

Yes, the USB/FTDI cable to xstreambee and then jumper cables from xstreambee to minimosd.

I think I've solved my problem, too. I plugged in an OSC480 camera and it works. The other camera had a 550tvl resolution, this one is 480. I had read that the max7456 chip struggles with some of the newer high res cameras.

Regards

James

That's good news. I am encouraged that someone else has this setup working. I can see a big advantage in making the OSD independent from the onboard video transmitter. You could fly the plane back, IFR if you will, in the event of video link loss. Of course the APM gives you other options in an emergency, but you can never have too many options. It is also one less component to carry onboard and power up.

It was a shame about the wdr700, that was a good camera!

I've just been flying with it. At least I can usually see the OSD now, but I have a new issue. For some bizzare reason, the OSD dissapears on a dark background. If flying over a light background it is there, but when I fly over darker trees or the river, it simply dissapears. Reseting it doesn't help ( by the way, check your reset button, mine was very lose and would cause a reset if you bumped the board).

There must be some kind of frame subtraction or something going on here as it just doesn't like some backgrounds. Could also be that 480tvl is still too high. I wonder what cameras this has been tested with!

Today I was able to bench test this setup. Using an XtreamBee FTDI adapter on the ground, I paralleled the data to the Minimum OSD and the FTDI/USB cable. The USB cable fed the computer running the mission planner. I did have to roll the Rx wire on OSD to get the both the OSD and mission planner to respond properly.

 

I discovered another limitation that may make putting the MinimOSD on the ground a moot point. As the video signal from the plane gets weaker the MinimOSD will blank the OSD information from the display. If the video from the plane completly goes away, then the OSD info shows up on a black screen. I can only guess the MinimOSD can not frame both the data and the video if the video starts getting weak. Without adding more video processing hardware on the ground, the MinimOSD is going back on the plane.

Now that I have used this setup some more, I am also having this problem. Any loss of signal quality means I go to a black screen, not even static.

I continue to get strange dropouts depending on the darkness of the backgrounds I am looking at. Putting it back in the plane is shaping up to be the better option.

I have put the OSD in my plane and most of the problems I had have gone away. Even works with my higher resolution camera. I guess the signal coming from the Rx is a lot less stable than it looks on screen.

 

Oh well, Ground based OSD was a nice idea but I guess this is not the way to do it.

I feel your pain! Back in the plane......it goes.

I am in the process of selecting components for my system and was zeroing in on the video system from Range Video.  Their package price seems to have come down, but the camera resolution is given as 600 TVL.  After reading this thread, it sounds like I might have trouble using this with MinimOSD.  Do you think that's the case, that it won't work?

Thanks,
Paul

Hi Paul,

The camera should be fine provided you install minimosd on the plane. All of my problems were when I was trying to use it ground based. It just doesnt work reliably on the ground side.

Since moving my minimosd back to the plane I have had no problems using it with my 550tvl camera.

James

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