Routing APM communications to Internet


I’ve been wondering, what would be the easiest way to route telemetry and commands from APM to Internet. Using 3G modem, would provide almost unlimited range (I know there has been some discussions about this in DiyDrones forum. Here in Finland the GSM network is very covering, but due the way the cellular towers are optimized, maximum altitude where the connection works is probably less than 200 m.)

In theory, list of required hardware is not long. One just needs to receive messages from APM and encapsulate them to UDP packets and send via 3G modem and vice versa. Unfortunately handling PPP communications is too large task for simple microcontrollers. I ended up using BeagleBoard for the sake of easy development and since I had one at hand. I realize that BeagleBoard (which essentially is full computer by itself) is an overkill, but it’s not very heavy and fits easily inside Maja’s fuselage. Basically any embedded system, capable of running linux and acting as an usb host would do. Maybe in the future I figure out some additional tasks for BeagleBoard to do.

The setup works quite nice now. Unfortunately I haven't been able to do much flight testing. Weather constantly sucks this winter here in Finland. As you can see I already installed skis, but there's not even snow, even though it's almost new year.

I wrote more detailed post to my blog, with link to sources:

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  • Here it is. Just change the IP and port number to your needs :) Command is in one line of course.

    sudo -u pi vlc-wrapper -I dummy -vvv v4l2:///dev/video0 :v4l2-width=352 :v4l2-height=288 :v4l2-fps=10 :sout='#transcode{vcodec=MJPG,vb=500,fps=10,scale=1,width=352,height=288,acodec=none}:std{mux=ts,access=udp{ttl=10},dst=}' :sout-all :sout-keep

  • Thanks Tommy, could you also please give my the VLC command line that you use?

    I've been playing with the Grabby device on my windows and for some reason the video quality seems lower than the cloned easy cap that I have.

  • @Paul: 2013-02-09-wheezy-raspbian.img is the image to use.

  • you can power it from an UBEC, no need for USB hub. you can strip an USB cable extender, cut the PLUS and GND wires and connect them to the UBEC while also keeping the GND connected to the RPI to have a common GND between all 3 devices (rpi, easycap, UBEC)

  • How are you guys adding power to the USB for the dongle? I would rather not have to haul a USB Hub air side. Maybe there are good connecting points for a castle 10amp BEC?

  • Thx Tommy, do I need to compile a particular driver for it or will it work with the standard drivers of Raspbian?

  • Yes, the powering of RPi is very importante. Remember to use common ground all over.

    I have been trying to make a film with my setup, but i just hate to hear my own voice on the video! :D

    I will make one with text and see if i can share that :-)

  • @Tommy: I got my Terratec device a few days ago but didn't have time to install it because it was too nice outside :). Could you please give me some tips before I start installing it? Shall I power it separately from the very begging? Thanks!

  • @Paul: I guess the amount of data is too much to handle for 3g network, but the tought crossed my mind as well :)

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