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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      • SERVO_TYPE.  Ghis is the correct param. Please advise. Thx. 

        • This parameter affects both servos. I have been providing extra firmware for those who had 2 different servos (one CR and one classic).

          • Jacub, ideally we would also like to support 2nd pitch servo as well. Right now I am using a simple servo reverser, but my servos are from different batches so one's  mid position is ~2° differwnt than of the other and  they are fighting each other constantly, I would love to be able trim out one of the servos, so they have identical mid positions. Unfortunatelly it is not possible with only one channel support. 

            In the mean time would you be able to provide either a hex or a source for APM2.6 with 2 diff servo types please :) 

            • You can find these files in my previous posts in this thread.

              2 servos for Pitch should be relatively easy, just add another output and assign it with the same signal multiplied by a factor with an offset (reverse and trim)

              • You are speaking to a person who can barelly compile with arduino IDE and max comment or uncomment #define's :) hoping this will eventually get into some sort of beta/stable f/w. 


      • I think I've misspelled the param name, will look it up tonight. 

  • Grant,

    i was hoping i could ask you, randy, and anyone else who is in the know (that is not me) could please either make some fixes or change the wiki. specifically i talking about the tracker actually working. sometimes i power everything up and the tracker works and sometimes it just sits there with pitch at 45 degress doing nothing but looking expensive.  it seems like there might be a sequence that must be followed when starting everything up for it to work. if there is a a sequence that needs to be followed i was hoping it could be added to wiki page. 

    also, scan doesnt seem to function. during tests, when the signal is lost it just stares off into the distance. or when i manually put it into scan mode it does nothing. im confused by this. i am hoping that when folks get time this can be as rock solid as the other projects. i trully appreciate all the hard work.



    • Developer

      It is on our list to sort out Keith.  Just a matter of getting some time.

      Thanks, Grant.

  • I have an idea on how to eliminate 3dr radio dependency of the tracker by pumping needed telemetry data through the Audio channel of the Vtx via simple and dirt cheap FSK modems such as this one:  The potential issue would be a low baud rate of 2400 of FSK modems, however I think adjusting SR values to output only GPS/Altitude (and potentially batt voltage/current consumption) should do a trick and lower baud below 2400. Now, the thing I do not know is would the Antenna Tracker firmware work without Tx connection?

    FSK 1200bps modem using a TCM3105. Contribute to kh4/FSK_modem development by creating an account on GitHub.
    • MR60

      Why would you not want to get the telemetry feed via radios if the objective is an antenna tracker that does that precisely? 

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