Henk wrote: > > Wavecrest uses algorithms for this and their software gives a spectrum. > > They also give some info on their site.
Henk, the paper you mentioned put me on the right track. Thanks. :) Magnus wrote: > In "Jitter, Noise and Signal Integrity at High-Speed" by Mike Peng Li, > Prentice Hall, ISBN 0-13-242961-6 it is covered in pages 200-207. > It converts the phase jitter Phi(t) into the autocorrelation function > R_Phi(tau) (equation 7.40) and then the phase jitter PSD can be estimated > using the fourier transform (equation 7.41). The phase-noise can then be > calculated using the standard L(f) = 10*log10(PSD(f)/2). It's pretty > straight-forward. While I don't have that book lying around here, going from the Wavecrest paper Henk mentioned, I did find out that indeed the method is to calculate the autocorrelation of the timeseries and then FFT this autocorrelation. The method even has this easy to google name: Blackman-Tukey. LeCroy has a paper with a short explanation that I found useful: http://www.lecroy.com/files/WhitePapers/WP_TechBrief_Var_of_Time.pdf > The autocorrelation processing is O(N^2) while the DFT can be done in > O(N log N) when using FFT. As usual these can be implemented in reversed > order such that first the FFT is done to the phase jitter and auto-correlation > can be found using O(N) post-processing. If it can be done in N log N that would be nice. :) > The phase-noise measuring ability of the SIA-3000 I have is not competing with > real phase-noise measuring sets. It doesn't say it can't be useful. And what I am trying to do will probably not even compete with that SIA-3000. It is more along the lines of... Hey I have these times stamps anyway. Now what can I do with those besides calculate a frequency estimate of the frequency under test? Fred ____________________________________________________________________________________ Sucker-punch spam with award-winning protection. Try the free Yahoo! Mail Beta. http://advision.webevents.yahoo.com/mailbeta/features_spam.html _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
