Hi everyone, I'm very happy to announce something that 3D Robotics has been working on since late last year in cooperation with a few very talented developers. Today we are announcing the 3DR Radio telemetry system, an open-source alternative to XBee telemetry set-ups, with superior performance, great range and a much lower price (half the price of the equivalent Xbee kit).
This is a 2-way, half-duplex wireless communication system with a standard TTL UART interface, based on HopeRF's HM-TRP data link modules, and custom firmware that improves upon the module's original features and performance.
The SiK firmware includes a bootloader that permits radio firmware updates over the serial interface, and radio firmware with configurable parameters. Updates and configuration are fully supported in the APM Mission Planner (press control-A to bring up the window below), and also possible through AT commands.
From the wiki:
- light weight (under 4 grams without antenna)
- available in 900MHz or 433MHz variants
- receiver sensitivity to -121 dBm
- transmit power up to 20dBm (100mW)
- transparent serial link
- air data rates up to 250kbps
- MAVLink protocol framing and status reporting
- frequency hopping spread spectrum (FHSS)
- adaptive time division multiplexing (TDM)
- support for LBT and AFA
- configurable duty cycle
- builtin error correcting code (can correct up to 25% data bit errors)
- demonstrated range of several kilometres with a small omni antenna
- can be used with a bi-directional amplifier for even more range
- open source firmware
- AT commands for radio configuration
- RT commands for remote radio configuration
- adaptive flow control when used with APM
- based on HM-TRP radio modules, with Si1000 8051 micro-controller and Si4432 radio module
Kit price is $74.99:
Individual radios are $35.99 (USB) and $31.99 (pins):
Kits and radios are available for purchase today, and they will start shipping next week.
Coming soon: a 3DR Radio XBee footprint adapter for both frequencies, compatible with our USB XBee adapter and Sparkfun's XBee Explorer boards.
We will also be releasing a version of the radios on both frequencies with an Xbee-compatible footprint, so you already have Xbee adapters, you can use them.
We hope you enjoy using these radios as much as we have during development, the simpler hardware and configuration tools compared to XBee provide a much smoother experience. We look forward to hearing your comments!
Huge thanks to the developers who made this happen: Team leaders Andrew Tridgell and Mike Smith along with Michael Oborne, Seppo Saario, Marco Robustini and others.
Comments
Excellent, now where do I get a bi-directional amplifier for the 900Mhz ones?
@Jason,
They are both config options on the 3DR radio. I'd suggest you read through the wiki page docs, then see if that makes things clearer. If it doesn't then please let me know!
Cheers, Tridge
Andrew Tridgell,
Alright, that's really great news! Having that kind of firmware flexability opens up some great possibilities.
Thanks for sharing....
Wow, its like they waited till I pulled the trigger on the XBee and then they introduced this. :( Oh well, Good work 3DR team, I cant wait to hear the reviews. Cheers,
Rick
@Jonathan,
yep, that shouldn't be hard. If you are in the USA, you can use any freq from 902 to 928 MHz. At 64 kbps AIR_SPEED (which is the default), you'll need about 100kHz between channels, and to meet US regulations you need to use 50 channels. So, you can pick any 5MHz band or wider for the 3DR radios in that range. See the wiki page for how to set that up.
To prevent interference, just keep the FPV system a couple of hundred kHz from whatever range you set for the 3DR radios. The high level of configurability of the new radios is one of their big advantages.
Also, even if you can't adjust the frequency of the FPV system, you'll probably find it works OK even with the default settings. The frequency hopping in the 3DR radios means it is quite resistant to interference from other radios.
Cheers, Tridge
Pretty cool! I am glad I waited :)
Unfortunately, I just got a 900mhz 1W FPV system from my friend. Any chance they I can get enough frequency separation between the two transmitters? My gut says not a chance
@Keith,
The new radios should perform better than Xbees because we have been able to build features into the radio firmware that we could never do with an Xbee. For example, the 3DR radio sends information to the APM telling it the state of the internal serial buffers and signal strengths. That allows the APM to modify its telemetry rates to ensure that you don't get serial overruns. That makes a big difference in terms of reliability.
The 3DR radios are also a lot more customisable. You can drop the air speed right down for very long range and you can enable MAVLink framing which optimises the packet layout to match the telemetry format that APM uses.
So I'm expecting that people will find these radios do a lot better than Xbees.
Cheers, Tridge
@Martin,
A 10% duty cycle is not nearly as bad as it sounds. I've tested these radios with a 10% duty cycle with AIR_SPEED=128 and ECC=1 and I can get continuous telemetry of all streams from APM at 2Hz.
The reason this works is that it doesn't just transmit continuously for 6 minutes then shutdown. The 'duty cycle' is calculated based on how many microseconds the transmitter is active in each TDM round. The normal duty cycle for an APM sending telemetry is only about 30% for typical Mission Planner settings, so 10% just means that your maximum telemetry stream rate is a bit lower.
So you can run with a duty cycle of 10% all day, and you will keep a good link to your APM. Your GPS data points will be a bit further apart, but it is quite usable.
Cheers, Tridge
Keith: There's no particular need to upgrade, but if you've been frustrated by Xbees "bricking" (an all-too-common occurance), you'll be pleased to know that they don't do that. They also have less packet loss and are easier to set up. But if your Xbees are working well for you, you might as well stick with them.
Anybody know if there is a reason to upgrade yet. I looked through the documentation and don't see why to upgrade. 156k to 250k and frequency hopping are two that pop out compared to the xbee's. Did I miss something?
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