figuring out the Antenna Tracker

3691139590?profile=originalNot many people know but we have an piece of open source software for controlling an Antenna Tracker.  It's been built by Tridge (Arduplane lead developer) for use in the outback challenge.

Sadly we have no documentation and, as far as I know, nobody except Tridge has used it.  Still given Tridge's track record on building great software I suspect it works well and if it doesn't, I'm sure we can fix it.  So to not let this piece of code go to waste, I'd like some help from people who are interested to give it a try and help me figure out how it works.

Here's the little that I know:

  • It runs on any of our supported board (APM1, APM2, PX4, Pixhawk, Flymaple and perhaps VRBrain)
  • For APM1/APM2 users building the code is as easy as opening our hacked ArduinoIDE and selecting File > SketchBook > Tools > AntennaTracker and then building in the normal way.  For PX4/Pixhawk, our autobuilder doesn't automatically build a binary but I can provide one if people are interested.
  • It can control a Pan and Tilt gimbal like this or this found on
  • It may or may not require a GPS
  • It must somehow receive vehicle position updates from the ground station which has the telemetry radio that is connected to the vehicle. Maybe through a USB cable.  Tridge probably uses the python ground station, MAVProxy, to passthrough the vehicle position data to the AT but perhaps we can get MichaelO to build out a similar feature in Mission Planner.
  • I imagine this antenna tracker could also be used to keep a camera focused on the vehicle which might be good for easing the burden on creating videos of our vehicles.

So if you want to give it a try please do and stick any findings, questions or issues below. Alternatively Issues can go into the issues list.

I'll start sticking things into the wiki as they become clear.

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      • Keith,

        I didn't abandon this project, I just put it on hold for some time. I have a lot of work recently and I can't find time for any side project, plus I don't have my tracker frame anymore (I am building a new one). 0.7.2 worked for me with CR servos.

        • I hope that didn't come across wrong. I just haven't seen a new firmware that truly works be released yet. I realize the developers have higher priority issues that they need to tackle. If I have the smarts to develop from where myself, I would. Since I don't, I'm kind of at the mercy of those who do. I've been working on mine for over a year and have yet to see it work with any consistency. I would really love to see this as an integral part of my Fpv experience.
          • I did not understand why the antenna tracker is not a 'product' like other in 3DR constellation : APM, Pixhawk, APM planner, MP, etc  because it's very important, according to regulation on video signal, to stay on a legal side.

            For sure, dev' here making a great job but there is a lot to do to have a reliable Antenna Tracker that works for everyone without tweaking for month to have something we could use each day. 


            • That's strange for me too. I'm playing with my own tracker (mechanical parts have done) but even with last version (0.73 guess it is) the tracker is not reliable. It sometimes work, sometimes work with offset (surprisingly not constant but with some ratio regarding to yaw position), sometimes doesn't work at all. Unfortunately I have not much time to play with it now, but during last months I did some research around my AT and still not satisfied.

              With these problems I would really appreciate reliable product (either with mechanical parts or without) from 3DR, because it is fundamental for some activities indeed, not only hobby.

              The hardware should not be a problem, because computational  requirements of AT are not high (even APM1 can handle this job easily). I guess 3DR should invest some resources into this area and develop serious antenna tracker either with HW or without.

              • Developer

                I certainly agree that we should stabilize the software more.  I'll try and put some more effort into that.

                As for the hardware, it would certainly be good if some hardware manufacturer came up wit h something that we could agree on as "the standard".  I wouldn't hold my breath for 3DR to step in and provide that standard though 'cuz they're all wrapped up in Solo with no end in sight.

                • There is an easy and budget DIY option:

                  a pair of these + a rotary tool to make cut outs for

                  2x Corona metal gear servos $12 + servo reverser $2.70 + 2 strips of aluminum will give you strong and solid pitch (2x servos so you do not have to mess around with hinges, servo reverser since AT firmware supports only one pitch servo)

                  Another Corona $11.xx + a Quick Release Plate $1.99 + some bolts/nuts/imagination will give you equally strong and solid yaw. 

                  so for under $30 it is possible to build a decent quality pan/tilt with enough space inside the boxes to install APM, servos, BECs, 3dr radio+bluetooth and even a videoRx, with enough space on the outside to mount 1.2ghz patch and a 915mhz patch. 

                  will post pictures when done :) 

                  p.s. is there any way to make max_yaw_servo unlimited? (continuous rotation)

                • I see on August 1 that the official antenna tracker firmware changed to 7.3. I can't find anywhere what the change was. Would you please let us know what changed from .2 to .3
                  • Developer

                    Its a fair question Keith.  What it means is depending on which version of AT that the GCSs see they will handle the text severity differently.  All versions will still work.  Just that from .3 onwards its different and more bettera :-)

                    Thanks,   Grant.

                  • Grant,

                    Forgive my ignorance but, does that mean no other version will work properly?
                  • Developer

                    The version update from .2 to .3 was done because of the text severity change.  The GCSs need a unique version from which they can be sure the severities have changed.

                    Other then that there was just a handful of internal development changes.

                    Thanks, Grant.

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