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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  • The rfd900x programmer and binary files are up on the web page now.

    RFD900x Flash Programmer V1.0.0.13.zip


    RFDSiK V2.53 rfd900x.bin at


  • I think it is already stuck in boot mode, i'm not able to communicate through AT commands, it always answers with "???" however i could connect to the other one and find out that the firmware is "Sik 2.53"

    The other radio responds as usual, when i connect it it starts blinking green, but the first one still on boot mode. 

    Is there any way i can upload firmware? just point me to the solution and ill figure it out.

    Thank you very much.


    kent Martin said:

    1.1 is the bootloader version.

    What is the firmware version you are running?

    Use AT commands.

    Mission planner should tell you, if you don't know how to use AT commands.

    There was an issue with rfd900x programmer Version which is on the web page at the time of writing.

    Don't use this to upgrade, or it will get stuck in boot mode.

    A new version will be posted soon.

  • 1.1 is the bootloader version.

    What is the firmware version you are running?

    Use AT commands.

    Mission planner should tell you, if you don't know how to use AT commands.

    There was an issue with rfd900x programmer Version which is on the web page at the time of writing.

    Don't use this to upgrade, or it will get stuck in boot mode.

    A new version will be posted soon.

  • 100KM

    Does anyone have a link to firmware version 2.4 (mentioned by Ken earlier)?  I've found links to version 2.4 for RFD900+ and RFD900u, but the RFD900x section is grayed out/no links.

    Firware Download Page

    Firmware | RFDesign Files
    Here you will find Supporting files, Binaries and Tools to use our products
  • Kent, thank you for your repply.

    This is what i get when connecting to the RFD XMODEM programmer, the firmwares i downloaded from github and the modem itself when plugged it in.



  • Rodrigo,

    1.1 Firmware I assume is on a rfd900+?

    PPM is not supported on RFD900+ only on RFD900x.

    Can you confirm your hardware?


  • Hello Kent, I just got a coupple of radios and have the 1.1 firmware and cannot find the latest... could you help me with this?
    kent Martin said:


    Please first ensure you have version 2.4 or later. There was a bug with ppm record on earlier versions.
    If yours isn't let me know, and I can send you the correct version.
    PPM input or outputs pins can be configured for your ground and air radios respectively.
    Set up PPM input and output before recording fail safe ppm signal.
    The air side radio should also record your desired PPM signal in the even of radio link loss. 
    ( You can do this with remote AT if you like, note it will give an error if you try and record the ground side).
    You should set your controls to whatever will let you flight controller know that something is wrong,
    Then type in the AT command to record the ppm stream. Check in Mission planner that the signal is correct, then record it.
    Put your controls back to normal and check mission planner has returned to normal, then turn off your transmitter and ground and check that mission planner is going into the correct mode for a fault.
    AT commands are:
    1. for PPM input (ground)(pin 15 of header GPIO1.1,GPI1_1R/CIN ) "ATI16 = 1 "
    2. for PPM output (pin 15 of header GPIO1.1,GPI1_1R/COUT ) "ATI17 = 1 "
    3. to record the PPM stream for link loss "AT&R"
    The PPM input will need to be level shifted down to 3.3V as it is not 6V tolerant, which is likely the level coming out of your transmitter.
    You can make one up with 3V zener and 1K resistor, or we will hopefully be selling adapters for this soon if you are not familiar with this yourself.
    Note you can't configure both PPM input and output on one device as they are the same pin and you will have to disable one before enabling the other.
    Note also that you configure the correct end and don't mix them up.
    Once configured you should be able to control your aircraft using the radio and use mavlink at the same time.
    Note, you might notice it's not quite as responsive due to delays, but it is very flyable. 
    If you're drone racing, it might not be what you're after. (maybe in the next version of firmware this might get improved on).
  • Pin 15 is what is assigned to PPM in/out. 
    So, you can either connect a cable from your transmitter accessory port to the RFD, or you can connect a receiver to the RFD.  If you connect a receiver to the RFD, you basically use the transmitter as normal, connect the receiver PPM output to the RFD900x pin15.

    In either case, you need to be sure the signal is not more than 3.3v, so you may need to build a 'level shifter' to drop the ~5v signal from your transmitter or receiver to 3v. 

    Then on the aircraft side, you take the signal out of pin15, and in to the PPM/RC input of your flight controller. 

    There is some configuration..  Most of the info is in this post from Mr Martin:

    Thomas Stanley-Jones said:

    I'm trying to visualize what I would need to replace the radios on my plane and quad with an RFD 900x.  I'm not sure how to connect my FrSky Taranis, or Spektrum, controller to the PPM on the 900x which would also be connected to the tablet or laptop.  Or is this not possible?  It would be great to only have one radio for the telemetry and control.

  • Can some one please tell me the best way to mount the RFD modems. I can mount it with double sided foam tape or I can mechanically fasten it with screw mounts and spacers.

    If I hard mount it will it be affected by vibration?

    Thanks in advance


  • yes there is have look here


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