Had a strange jitter on the camera mount of our Hexa XL MikroKopter... Took some time to find out where it came from, and it appears Graupner receivers (GR16 and GR24 tested, latest firmware, with mx20) create a jittery PPM signal!

Has anyone noticed that too? That would be worthy of some feedback to Graupner...

http://www.youtube.com/watch?v=9E-uWsQVLU0

Hello Kilrah,

thanks for the documentation of that effect.
I tested that and observed a similar effect on channel7. That is the only channel with the jitter in my tests. The Jitter is about max. +-5 counts.
Also I tested that with a different RC-System to make sure it is not in the FC-Firmware.
I informed Graupner about that and hope they will find a solution soon. In the meantime you should use a different channel for the camera-stabilisation.

The Jitter will be no poblem for a function like Altitude-On/off or something. There it is well filtered.

Regards,
Holger

welcome back, kilrah

If my selfmade servo tester is implemented correctly, my gr16 has 1 µs Jitter in signal length and very constant 90µs signal cycle jitter on several channels. but i cannot measure the jitter of the the pwm-signal on channel 8 without major modifications.

Hi again, been some time indeed

Holger, have a look with channels at different positions. For example, set throttle to minimum, CH5 centered, move right stick, look at the jitter.
Then set throttle to maximum, move right stick in the same way, jitter will be a bit different. If you have a switch on CH5, set that to 0, set throttle to 0 too, move the right stick towards the "low" side, there will be some jitter on CH6. Now set CH5 and throttle to 255 and move the right stick in the hiugh side region, some jitter reaches CH8. I managed to get some on CH10 too with certain values on CH6-8, don't remember exactly how.
The jitter amount and distribution really depends on the positions of all channels, although CH7 is indeed the most affected.
For now I simply moved the tilt control to another channel and set the manual control speed back to 60, where it's barely noticeable and not disturbing in video. But as we work with a buddy box for the camera operator we need to have tilt, zoom, shutter, yaw on channel numbers <=8, it gets tight...

And if anyone wonders, the reason for setting manual control speed to the fastest is because we programmed the buddy box TX to work in slew mode on the tilt channel for better movement smoothness. When the operator isn't there, I programmed a 1s delay on the mx20 with a flight phase to replicate the slowing down that's done by the FC with the default settings. So with trainer switch OFF -> flight phase ON, pilot has smoothed control, with trainer switch ON -> operator has camera control in slew mode with no delay

I'll check the PPM signal from the HoTT RX next time I go where the hexa is, I didn't have the scope with me yesterday when I found out the source of the problem.

Anyway, thanks for getting that back to Graupner, figured out here would be the best place to report as you have direct contacts

I just got this elder Version form Graupner. That works fine without the Jitter.
http://www.mikrocontroller.com/files/33508_gr_rx8_5a80_f9.zip
Please try that.

It also has all the V4-functions and is compatible to our 0.88m

Regards,
Holger

Thanks, will try that this afternoon! Would you by any chance have the same version for the GR24?

Can confirm it works fine on the GR16!

Any news from Graupner about the fix for the GR24?

Would really like the GR24 version as well.

Graupner has udated their V4 software (without telling anything at least to me ! ...)

but i have seen in the package that the receivers versions are now from 4 of july

names have changed too:
33512_gr_rx12_3a70_bf
33508_gr_rx8_6a30_f9

before it was (june)
33512_gr_rx12_3a40_bf
33508_gr_rx8_6a10_f9

and Holger version for gr16 was
gr_rx8_5a80_f9

there is a firmware update for MC32 only

???
regards
Denis

nosig78 meinte

names have changed too:
33512_gr_rx12_3a70_bf
33508_gr_rx8_6a30_f9

We tested these Versions and they are fine - I will Update our HoTT-Software-Package accordingly.
No need to update the Transmitters.