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:
I have this issue with a pair of RFD868+ with ECC on. The symptoms are that when connecting to the UAV from MP it does connect, but then sometimes times out (or is very slow) on "Getting Params". What puzzles me is that most attempts to connect (in similar or identical conditions) actually work, with the params being downloaded quickly. Then in maybe 1 out of 5 or 10 cases, the problem mentioned above happens and there seems to be no way to recover other than resetting both modems. Due to the nature of our application, we need a reliable long range link. Therefore we'd really like to use ECC if at all possible. My questions:
- Is the statement made for the RFD900+ below also confirmed to be true for RFD868+ (I assume so)?
- Is the recommendation then to plainly not use ECC on the + model or can it work when other features (which ones?) are disabled?
Thanks much in advance,
Don LeRoi said:
I have RFD900 modem set. How can I configure the GPIOs as PWM inputs/outputs?
We can actually get what ever mavlink data we want ..such as these examples ..in the photos
Yes I saw there was a standard packet interface. But what is the purpose?
How will the taranis know how to interpret your own data format? You would need to program the taranis to interpret the data and display the data somewhere? As for sending the other direction, again what would be sent? how would the other end be programmed to interpret it?
Is this not duplication of the purpose of mavlink? Or are you wanting to not use mavlink in favour of your own home grown messaging?
If not wanting to use the rfd serial data stream as mavlink then it could be used for your personal stream instead.
However it would not support the 2 adc's and link quality in taranis format. From the circuit the tx/rx pins would need swapping polarity and have to check the taranis tx pin did not exceed the 3.3 v Limit of the RFD900x rx input.
Software could probably invert them, but we need to understand the use case and if it will be useful?
There are a number of apps available ATM for android and IOS that support mavlink, would this not be a better existing solution than a roll your own? A smart device can be attached to taranis tx similar to DJI setups.
Joe Street said:
Yes that is correct. You need an level shifter / inverter to get TTL serial. Some people have used a RS232 to USB converter with success. The three pieces of data you mentioned are native to the taranis but beyond that it is just a transparent link. you can add whatever packets you like. These come out the SPORT interface on an X series receiver and likewise whatever data goes into the receiver on the model end come out the serial port on taranis.
Looks like it is rs232 levels and not TTL, so inverted, and the protocol is their own and not mavlink.
Also there are only 3 pieces of data, link quality, and 2 analogue channels.
This is very limited compared to mission planner or other mavlink supporting apps.
Probably best to use a smart device running mission planner or other app to show a more advanced set of telemetry data.
Since Taranis is so limited and requires a lot of effort to produce what mavlink does and much more it would be easier and IMO much better to use a mavlink supporting device to display telemetry. RFD900x is not intended as a PPM radio device alone, but rather PPM is an addition to mavlink telemetry and the 2 would be used at the same time.
A wifi link from RFD900x to a mobile device (mounted on taranis) with a mavlink app would be a better choice here I think....
Joe Street said:
sorry for the late reply , yes the taranis has a tele port but we first have to use a teensy board to convert the mavlink messages to the FRsky protocol It is also possible to connect a blue-tooth module to the RFD900 mavlink data port and then a connect laptop/tablet with mission planner to it with blue-tooth wireless.
kent Martin said:
More info on Taranis serial connections:
The specification for the telemetry port on the Taranis is here: