Indeed accuracy and stability are two separate things. Here is a very good page that describes and shows the differences: https://www.febo.com/pages/stability/
Yes, the loop bandwidth impacts the performance. What I wanted to highlight, with the remark, was that the role of the earth stations' LO stabilities may be greatly overvalued when not looking at the total system end-to-end performance. From where I sit the latter seems to be downplayed or overlooked. The concern, that sparked my original post "High speed data use", was an understanding that a stability of at least 1e-12 was required. Later I found out that this number was over 10 000 s =:~|
Thus there are several things to (re-)highlight
- 1e-12 is very GOOD, higher is adequate
- looking over a period of 10 000 s is nonsense for high speed data communication in the light of both 1/Tsymbol and http://g4jnt.com/QO100_Stab.pdf The "system" and decoder should be good enough, already, to sustain such a time frame otherwise they should be scrapped
- short term stability is important with respect to FFT bin size, 1/Tsymbol, e.g. if Tsymbol is 10 ms -> 100 Hz am effective LO wobble of 5 Hz at 10 GHz should not be a problem for a robust modulation with more than 1/Tsymbol tone spacing and a properly designed decoder
- a suitable modulation has to be used for the purpose, see External Content www.youtube.comContent embedded from external sources will not be displayed without your consent.Through the activation of external content, you agree that personal data may be transferred to third party platforms. We have provided more information on this in our privacy policy.
- don't expect to use a narrow band and shoulder-to-shoulder tone location at 10 GHz
- using HF designed modulation(s) in the 10 GHz range is FAR from optimal irrespective if this is PACTOR IV or WSPR. Decodes may happen but Link Probability will be low even if the signal is loud especially due to path irregularities
- a balanced approach will be much more cost effective that an over-engineered and over-spec'ed earth station LO
- it all boils down to the end-to-end performance
I don't think moving my original message into an existing thread of LO stability discussions was a good idea. It downgrades the issue of "High speed data" use to be only a question of the earth stations' LO stabilities, but, what I want to highlight is quite opposite.