Hi,
I did a small project initially for FPV, which is basically a virtual cockpit in 3D, showing data collected from an onboard (remzibi) osd.
A video will better describe what it does :
The originality is that the telemetry data is sent via the small black and white bars above and below the digits in the OSD. This is decoded by a computer at the base station, and from this all sorts of calculations and displays are made.
Now I'd like to make it work with the UDB, to be able to have more instruments such as the artifical horizon, turn coordinator, HUD pitch angle etc. I've seen there is a sparkfun board with a max osd chip which can allow to add characters (and the small bars) on the transmitted video.
Does someone already use it ?
Another track i'd like to explore is simply using a sync extractor such as lm1881 and send data over one or two (visible) video lines.
I've seen also that with the UDB it's possible to use an XBEE module for the telemetry data, what's the max range of such a module, I mean has someone tried to use a very directionnal antenna to push it really to its limits ? For comparison, in FPV there's someone who managed to transmit video signal to 89 km using a 24 dbi grid antenna. That's why I think the video can still be used to transmit data over long range.
Notice that my project already includes an antenna tracker (based on the $20 sparkfun polulu micro usb to servo adapter), so a directionnal antenna is not an issue.
What do you think (about all of this) ?
Replies
You could use some other DIGI sourced (www.digi.com) modules, namely Xstream modules, that cover up to some kilometers (they say up to 32 but I seriously doubt it) and provide 19.2 Kbps of effective bandwidth.
Those are just simple virtual serial cables: you plug one in the board and the other in the computer (or better USB-to-serial adapter) and you have a working serial pair.
Problem with the antenna is that you can't use a very high gain directional one on the drone, unless you want to experiment with auto-aim systems (go ask NASA if you do). If you can/want to plan for the drone to operate in a restricted geographical area, then at least you can mount a high gain antenna on the ground station with the previously mentioned limitation that the drone would then have to be confined to the geographical space under the antenna lobe. Keep in mind that these lobes may be very narrow (the higher the gain, the narrower the lobe): crossing their boundaries may well end up in total loss of communications.