Hey Folks.

While looking around on the interwebs today for alternatives to the Digi Xbee 868 modules for use in Europe, I found this from http://www.rfsolutions.co.uk.  It's specifically the Tiny Pro with external antenna that caught my eye. (The photo above is from the smd on-chip antenna version)

TINY PRO

• High Power - Up to 500mW
• Serial Baud Rate 1.2 to 115.2Kbps
• RF Baud Rate up to 38.4Kbps
• Range up to 4KM using external antenna

From the manual for the TinyPro:

"This band is free to use but the module and the user must respect  some limitations. Most of  these restrictions  are  integrated  in  the  conception  of  the  module,  except  the  duty  cycle.  The  869.400  to 869.650 MHz band is limited to a 10% duty cycle. This means that each module is limited to a total transmit time of 6 minutes per hour. It is the responsibility of the user to respect the duty cycle"

It looks fairly expensive, and I don't think the baud rate is as high as the Digi modules, but asking the user to enforce the duty cycle would allow us much more control.  Assuming we wouldn't just ignore the DC entirely, we could allow the APM to control it rather than having to hack it as the current thinking on the digi 868's suggests.

Has anyone tried this, or have any comments on suitability? Perhaps there are other 868mhz modules out there who also have less draconian enforcement of the DutyCycle?

Jim

Today I flew my Twinstar with APM in the hotseat. It's the second flight I've had with it wired in, but yesterday I was only using the stabilise mode. It's been a couple of great days from a weather and wind point of view, so ideal for testing.  The Stabilise mode is lovely.  The Twinstar (mine has a stock power system) when it is trimmed up is a super stable platform anyway, so I'm not too surprised that stabilise didn't have a massive impact, but it was certainly noticeable and very pleasant to fly!  The plane does have about a 5 degree nose down pitch when hands off (in stabilise) and I don't know how to fix this, can it just be trimmed out with the radio?  I thought the AP would compensate for any trimming I did to the control surface, and the fact that it has a nose down attitude is probably an autopilot config issue.

Return to launch was interesting.  I took off in stabilise mode and flew fairly straight away into the wind gaining a bit of altitude.  I then changed mode to RTL and took my hands of the control for the next few minutes.  The plane held attitude well, and executed well controlled turns.  However, you couldn't in all honesty describe what it was doing as a circle overhead the launch site.  Figures of eight perhaps, it seemed to be hunting for something.  It certainly seemed to be controlled and comfortable in the sky, I wasn't too worried.  I still don't understand it's behaviour though.

I would like to share the log file with you, but I can't.  For some reason this flight wasn't logged.  The previous two were and I have the KML and log files for those (not huge files, probably about 3-4mins flying each). Log three only shows one 'page' of data.

I will fully admit that this may all be my own fault.  I'm still learning, but in my excitement and the heady sense of progress, I havn't run the tests and tuning using FBW_A that the manual suggests that I should do.  I've not got my head around PID settings, and I suspect that this is the root cause of the issues i was seeing with RTL.  I'm guessing the AP couldn't hit it's mark to begin the orbit.

If the weather holds I'll be out again tomorrow to diligently follow the FBW_A tuning guide!