RFD900, RFD900+ - New long range radio modem

Hi All,

I would like to introduce you to a new radio modem that we developed for very long range datalinks!


Some of the key features of the RFD900 are as follows:

  • Multi point and point to point link capability.
  • Long range >40km depending on antennas and GCS setup.
  • 2 x RP-SMA RF connectors, diversity switched.
  • 1 Watt (+30dBm) transmit power.
  • Transmit low pass filter.
  • > 20dB Low noise amplifier.
  • RX SAW filter.
  • Passive front end band pass filter.
  • Open source firmware / tools, field upgradeable, easy to configure.
  • Small (30 x 57 x 13 mm), light weight (14.5g).
  • Compatible with 3DR / Hope-RF radio modules.
  • License free use in Australia, Canada, USA, NZ.


These modems are designed to support long range applications, while being easy to use and affordable.  

These modems have been flying in various platforms and have demonstrated excellent performance in real applications. 

RFD900 modems are now available at: http://store.rfdesign.com.au

Support within APM planner and the radio configurator from Michael Oborne is already available.

It works seamlessly with APM planner, all radio Mavlink parameters are available.

Update, December 2014:  The RFD900+ with improved specifications is available now at:


Seppo Saario



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  • Hi Seppo,

    I sent this email to RF Design on 8/31.  Maybe you didn't get it, either?

    Hi RF Design,

    For several years, I’ve used your RFD 900s in my ground stations to communicate with either RFD 900s or 3DR radios on my aircraft.  I currently have 8 ground stations happily talking with aircraft using ECC.  I recently purchased six RFD 900+ radios and discovered they will not communicate with my RFD 900s or 3DRs when ECC is enabled.  They will only communicate with other RFD 900+ radios if ECC is enabled.

    When I use two 900+ radios with ECC enabled, both units have solid green LEDs and blinking reds when they communicate.  However, with a 900+ and a 900 (or 3dr), the 900+ has a solid green LED and constantly blinking red LED (handshaking?), but the remote 900 (or 3dr) is always blinking green.  The remote isn’t detecting the 900+, but the 900+ is detecting the remote.  If I disable ECC on both ends, they link and communicate.

    It is important to me that new ground stations that use RFD 900+ transceivers are backward compatible with my existing aircraft that use either RFD 900s or 3dr radios and that they work with ECC enabled.  I understand that it is your intention that the 900+ be fully compatible with both the 900 and 3dr radios, but right now that is not the case.   

    Please let me know if you have a firmware fix for this.

    Is this something you are working on?  The improvements to the 900+ modems aren't of much value to many of us if they won't work with our 3DR or 900 modems.  


    • Hi Don,

      There has been a bit of work back/forth over time with ECC.  The problem has been limited code space available on units with features that have been added.  http://files.rfdesign.com.au/firmware/

      Has the current and a few good historical versions.  RFD900p V1.9

      would be worth checking with compatibility with 3DR modems and older firmware.

      My experience with ECC has been that some times it has trouble loading parameters in mission planner, and the extra correction capability has not really been needed for most applications.  As a result, it hasn't had much of a focus over time.  In addition, ECC doubles the bandwidth requirements for the link, reducing the telemetry rates available.

      Modem firmware development has slowed a little, the next features needing to be tested are AES encryption..


      Firmware | RFDesign Files
      Here you will find Supporting files, Binaries and Tools to use our products
  • Do anyone know if it is possible to make the RFD868+ modems output a continuous unmodulated carrier? I would like to measure and verify the output power.

    • Hi Ikaros,

      It is possible to setup a custom version of firmware to do that -


      is a version of firmware that we set to transmit 2 sec pulses at 922MHz for testing for one specific application.

      To set the RFD868 modems to do a similar thing, the frequency needs to be set to 868-869MHz or so.

      Hope it helps!


      Tools and firmware for the Si1000 - Si102x/3x. Contribute to RFDesign/SiK development by creating an account on GitHub.
      • Hi Seppo,

        Ok thanks a lot!

  • Hi.


    I have been doing some range testing and I would like to ask you about the recorded data.

    Here is a typical plot from one of the tests:


    I don’t know why 3 of the variables suddenly logs the same value, have anyone else had the same experience?

    • Hi Ikaros,

      I have not seen that before...  The only thing I can think of is that the modems have lost lock for a moment?..  The local noise level is fluctuating a lot to very high levels..  ~92 or so, peak !...  What kind of area is the testing done in?,  countryside, or urban areas?...   It looks to be a very RF noisy area, some times if there are mobile phone base stations nearby, they can increase the noise floor quite a lot.


      • Hi Seppo,

        Ok, the testing was done over water close to a village at 7 km range. Will update here if the problem appears again.

  • Hi Patrick,

    It looks like some emails have been lost at our server end?? - Could you send your email and order info via message here please and I will look into it for you.


  • Patrick the Chinese are the worst about this, I wouldn't have expected this out of the Aussies,

     Call 214-702-6286 HeliBatics.com and get hold of David, sometimes his wife answers the phone, she is Vietnamese and a very nice person, her english is a little rough but you will be able to understand her, just ask for David and he will fix you up with anything that the RFD900+ needs. he is well informed about 900.

    HeliBatics.com is out of Texas

    Check out this


This reply was deleted.


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