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A big enabler for UAVs going forward, especially with respect to commercialization, will be improving telemetry range. On that note, I've released my MAV Downlink Android application and associated tools today.

MAV Downlink opens up a new communication pathway for you to talk to your UAV while it is on a mission. This pathway uses an on-board Android smartphone to push MAVLink communications onto the Internet, then adds an intermediate server that hosts these communications and binds them to interested Mission Planner applications.

Pictured above is the general gist of the application.

I have been using it for the last few months to be able to communicate with my Sky Hunter in flight at essentially any range as long as I am at a field with good cellular service.

I know this idea isn't totally unique as there are several guides on how to enable UAV telemetry using cellular modems. To my knowledge, though, this is the first application that enables you to accomplish this easily using an old Android smartphone you probably have laying around. The big gotcha is that the smartphone must have an OTG compatible USB port. Fortunately, there are many cheap phones with these, notably the Galaxy Nexus:
http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2050601.m570.l1313.TR0.TRC0.H0.Xgalaxy+nexu&_nkw=galaxy+nexus&_sacat=0

Right now, this application requires you to run your own dedicated server to host communication between the onboard smartphone and your MAV mission planning application. It also sends MAV commands in the clear with no authentication or encryption over public wireless airwaves. As such it is only really useful for hobbyists with good knowledge of networking.

It has also been brought to my attention that the Pixhawk cannot be connected to a standard Android phone via OTG. You may be able to put together a custom powered hub that connects to the Android phone but I cannot make any gaurantees. This has been tested on APM 2.6 and 2.5 boards.

I would like to develop this application further by adding dedicated servers so that virtually no set-up is required on the end-user's side. This would also enable me to add authentication and encryption to the communications channel so people using this do not risk their UAV being hacked.. no matter how unlikely that might be.

However, it works fine for me right now. Before I put any effort or money into improving it, I wanted to gauge public interest in it. Please let me know if something like this interests you by dropping a comment below.

You can try the application now. Here is a link to the Android application:
https://play.google.com/store/apps/details?id=com.appliedanalog.uav.mavdownlink
And the users manual:
http://www.applieduas.com/mav_downlink_advanced_manual.pdf