@DD5ER: thank you 
then it seems that my RX stability here is not to bad. But i'm still not happy about the SDR-Stick...
My OCXO for the LNB is powered 24/7 but the RTL-Stick cools down when no SDR SW is running.
Every time i power up the PC (and then the SDR-Stick) it takes about 15-20 (30 measured) mins till the drift of the Stick is negligible.
A direct supply with 5V on the SDR-Stick does not help because the stick warms only up when accessed via SW.
Has anyone tried to lock the RTL-SDR to a more stable reference than the internal 0,5ppm TCXO with 28,8MHz.
Could a 27MHz OCXO (i have some of those here) work? Or is that to far away from the 28,8MHz?
73s DB8TF
The Doppler deviation at 21:29:00 UTC was -11 Hz at QTH Düsseldorf for the frequency 10489.500 Mhz.
Regardless of the other things that still influence the frequency deviation, it fits
Is this Doppler deviation changeing slowly or jumping rapidly? When testing FreeDV mode2020 we have sometimes very good SYNC behavior, but sometimes not. If the Doppler deviation is changeing very fast, that could be seen as a phase jump and mess up the decoder. So I a curious to know.
73's Gerhard OE3GBB
Hi Michael, thank your for your excellent explanation. Is there a online data base of the Doppler shift measured for QO-100?
Thanks in advance Geri 
Hi.
What are the units on the Y axis? and if Hz, is this at 26MHz or 739MHz etc. - Just trying to appreciate the real life performance of a 0.5ppm TCXO
Thanks David
Maybe I missed it, but is there a feature in SDR-Console to write this data from the beacon lock window over time to file?
73, Oscar
I suggest reading the blog posts from Daniel EA4GPZ...
und natürlich hier im Forum:
DB8TF: sorry, but my Excel-program was overwhelmed by the sheer number of data, also I was not aware that only 10.000 samples are collected in one go. Therefore I can not provide any graphics.
My SDR-RTL-stick seems to stablizie after a few hours and stays pretty contatnd in the plus/minus 20 Hz window after that, so your OCXO seems to work fine.
Best 73
Holger 'Geri', DK8KW
I stabilised my rtl sdr stick with an external 28.8MHz signal which is locked to a 10MHz gps disciplined ocxo. The only thing i buyed was the 28.8 MHz crystal (https://www.mouser.de/ProductD…CEO%252BqkQSOruaeLQ%3D%3D). Circuit: 28_8MHz_Ref.PDF, Arduino code: adf4001_28_8_MHz_Attiny85.txt
73
Andreas
I had my equipment running over the last 24h for this experiment.
My hardware was a GPSDO disciplined Pluto SDR as RX for the IF.
And a LNB also GPSDO disciplined.
GPSDO was a dual channel Leo Bodnar unit programmed for 25MHz (for the LNB) and 40MHz (for Pluto) outputs.
The SDR-Console measured peak-to-peak drift was +/-26Hz over 24h.
See attached EXCEL graph below.
73 de Oscar
