Hello Henry, Didn't know that one yet, so will check it out. Thank you for the suggestion! :)
regards, Fred ----- Original Message ---- From: ehydra <ehy...@arcor.de> To: Discussion of precise time and frequency measurement <time-nuts@febo.com> Sent: Tue, February 8, 2011 5:24:39 AM Subject: Re: [time-nuts] Calculate spectral content from a series of zerocrossing time stamps? SpectrumLab uses the Goertzel-Algorithm to trim the time reference to the millisecond range. Maybe that is comparable and as algoritm transverable? - Henry J. L. Trantham schrieb: > DFT? Direct Fourier Transform? > > Thanks, > > Joe > > -----Original Message----- > From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On > Behalf Of Tijd Dingen > Sent: Monday, February 07, 2011 9:02 PM > To: time-nuts@febo.com > Subject: [time-nuts] Calculate spectral content from a series of > zerocrossing time stamps? > > > > > Consider the following scenario. We have a signal source of about 10 kHz, > with unknown phase noise. Let's for simplicity's sake assume for now that > the phase noise is large enough that it will be detectable by the following > approach. > > We measure every zero crossing with lets say 1 ns accuracy. So we have a > signal with a nominal period of 100 us, and we can measure every zero > crossing to within 1 ns. This gives you ~ 10,000 data points every second. > > Now how does one efficiently calculate the spectral content based on these > 10,0000 zero crossings? The end result would be the spectral density, > centered around that nominal 10 kHz frequency. > >> From what I could find so far, one method to go about this is use a > Lomb/Scargle Periodogram. And specifically the method by Press & Rybicki > that extirpolates the unevenly timed samples to an regular timed mesh, after > which a regular DFT is done. > > This is a nice enough approach, but you pay a computational price for the > fact that this algorithm is able to handle more generic inputs than is > needed in this particular case. So possibly there is a more efficient > method, only which one? _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.