GPSProfile.JPG?width=300Graupner is a popular vendor of RC equipment here in Europe. I thought it would be great if we could use they telemetry protocol for ArduPilot. And here it is, HoTT v4 for use in ArduPilot for everyone. It's still fresh code and it's tested with ArduCopter v2.7 on APM2 only, but it works fine since few weeks. There are many possibilities to use HoTT in ArduPilot project, at least for people with HoTT RC equipment :)

For more details about HoTT and the implementation visit project homepage.

Here a sample screenshot:


Hope you like it!



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  • Im pleased to hear that some of you find this HoTT implementation useful.

    @Stephan: drop me a line about your text mode results pls!

    The project Wiki has been updated and i hope we covered the most important topic there now. The current version works well for me on APM2 with ArduCopter v2.7.1. It's still untested with ArduPlane and other project forks, but i don't expect any difficulties to reuse it here.

  • Krzysztof: now I see that was you who said something about 1,2km.

    BTW: I do not consider altitude to be any bigger problem than distance, actually there should be more noise (WLAN/BT/microwave) at lower altitudes.

  • no, what I am saying is that I had good connection till 3,5km , altitude ~300m  - with telemetry - no seeing any telemetry problem (the packets *from* the plane still got back to transmitter)  - over that , maybe about 3,8km there were too much loss so it RTL'ed .

    I am saying that my experience is that telemetry is as good as needed. - contrary to the other experience decribed here.  But you know, people do bad mounting, bad antenna direction, have noisy equipment or place the equipment too close to other TX... then complain.

  • T3

    Andke pls clarify.

    Hott is also RC connection. So what was going on, is your story also unreliable?

    What was the altitude at that time?

  • Great ! - for those who doubt, I've been at 3,5KM range, when RC connection were unreliable, still receiving HoTT

    - Hope it gets into ArduPlane as well, and ultimately, into the master GIT

  • Additional comment after looking at your project page: The text-mode would be capable of enabling a full GCS! I have an Unilog2 and it uses the textmode for configuration in that way.

    textmode is a true terminal session that allows any text-output in the given screensize, so although it would be only 1/3 the speed of the XBEE GCS it would be a super-cool replacement for the arduino-based GCS. The only barrier might be that you have to implement the code for the user interface onboard the APM and just send textscreens to the radio instead of having a GCS that speaks MAVLINK.

    Will try this weekend.Otto

  • Awesome!!!!! Just what I have been waiting for.

    to shed some light onto the technical aspects (as far as I have been able to grasp):

    It works with 19200 bit/s, hardware interface is single wire UART. There already is an implementation for Mikrokopter that Graupner fully supports.

    The range... It has been guessed that the telemetry emitter integrated in every receiver works with approx a quarter of the power of the radio (which would mean 25mW) but due to the better geometry of the antennas (and antenna diveristy as of the GR-16 8ch receiver) still essentially gets full range.

    Experience reports at least confirm that generally you have a stable link within range of vision.

    Timing is one frame for every four frames from the radio (1 frame/40ms then)

    You might want to check here for more details:

    (German only, this source has a business relationship with Graupner but is not an employee)

    Thanks for your hard work!

  • I don't think Graupner designed HoTT for long range or high speed. It's a very easy protokoll to transfer and display some telemetry values. Nothing more and nothing less. There is a benefit for everyday ArduPilot user like me who don't want to carry the whole Ground Station all the time but want to have some telemetry anyway. There are better and reliable solutions for "real" telemetry applications then HoTT.

    Btw. im not working for them. Just bought a RC system from them and played with it a bit. And the results are what i want to share with the community.



  • T3

    First, are there any reliable measurements of Hott range vs altitude, since if this stops sending aroudn 1.2km, you could as well use xbee pro with much more bandwidth, there are rumors they do not collide with hott. Plus, the phase delay is maybe 50-100ms.

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