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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Glen, take a look here on the QGroundControl support forum.
I found a post exactly like yours.

Hi guys, wow this thread is huge!

I don't know if it has already been mentioned on the previous pages, but I need some help with my RFD868+ links please. I bought two pairs of links from RFDesign (the other pair being RFD900+), but it seems that all the links on RFDesign's site for the RFD868+ modem points to resources for the RFD900 modem.

And now, as it happens to be, my RFD868+ modem pair keeps breaking link and loses signal quality: 

I have even hooked up a spectrum analyzer just to see if there's some ridicules irregular interference in the area from external sources, but the band was clear.

So as a first question, can anyone please point me to correct documentation, firmware & software config links I can use to debug my 868 modems properly? Or let me know if all the resources are identical for the two link versions? 

The second question then, does anyone know what I should try to fix it? (It does not look like there's obvious hardware faults)

Any help would be much appreciated. Thank you

can you post a pic of your radio settings ?

Hi Pau,

The 868 does not work with the standard firmware. Use the multipoint firmware instead, apperently it handles synchronization better. The only downside is that you loose the logging of the link quality so it is harder to debug the telemetry

Sooo... this is just fabulous... :(

My 868 config started as such, with RFD config tool v1.6 (before uploading firmware):

and then settings after uploading multipoint firmware:

So the new firmware is on, with factory default settings loaded. And for most of the parameters I can reset them, except for upper and lower frequency channels. I only have the option to set RFD900 modem channels. So then tried to load the parameters through 3DRRadio config (where I will be able to type specific channel frequencies into the dropdown label), but an error occurs when I even try to read the settings. All the text fields are not populated:

So now I basically need to crash course how to edit them through AT command in a console. HyperTerminal didn't provide any feedback after I tried entering config mode of the modem (+++). It only worked (replied with 'OK') after I sent the command through a serial port connection via C#.

Isn't there an existing interface out there for the 868 modems? I don't really want to write and debug a c# application for this

Jip, I've got that part thanks. The problem was with entering config mode on the modem with '+++'. Anyway, think Hyperterminal added new line characters, so switched over to Termite.

I now get into config mode, but can't manage to retrieve or set any data on the modem with the AT commands. The modem just echos the command back to me... so it probably gets rejected?

For instance I enter '+++' and get 'OK' as acknowledgement. After that I enter something like 'ATI5' or 'ATI', 'ATS8?' etc. but the command is just echoed back to me

I must admit, I haven't worked with AT commands a whole lot, but it seems straight forward... Am I missing something?

Why dont you use MO 3dr radio config terminal ?

I hate to suggest yet another terminal emulator, but puTTY is all I ever use on all platforms.
And it is easy to adjust the end of line settings, though I don't think I've had to change the defaults for anything in the last 15 years.

Thanks for the suggestions guys! I don't like to spam forums, but it's nice if someone is able to help you out.

Paul beat me to the reply. I actually saw the terminal tab within 3dr interface after a while (which I didn't know of before) and gave it a shot, and now wanted to mention here that it worked. (I did however repeat the firmware upload step also, to ensure that nothing's "screwy").

Thanks for everything. I'm eager to test out the range of these links. It "should" be the bomb! :)

Seppo said:

Hi John,

Have replied to your email.. Arranging a replacement for you.

For the record, I received a replacement the next day and all is well!
Thank you so much

Thanks for the link John,

Don has given me some suggestions, but still no joy in complete fix. I have managed to get the telemetry data working between ground modem and air modem, however, as soon as I turn on my Taranis radio, I get a "communication lost, communication regained" error repeating so there seems to be some interference happening now with the 2.4ghz radio.

Any thoughts on that issue?

John DeVere said:

Glen, take a look here on the QGroundControl support forum.
I found a post exactly like yours.

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