08.02.2011 08:17, Poul-Henning Kamp: > In message <[email protected]>, Tijd Dingen writes: > >> >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. > > Just knowing the time of the zero-crossings is very little information > to go by, but you have to make some kind of assumption about the > perfection of curve shape between those points, in order to say > anything meaningful.
As far as I know a bandpass signal is described uniquely by its zero crossings to within a constant. That is due to the Weierstrass factorization theorem. A more practical foundation is outlined in "B.F.Logan: 'Information in the zero crossings of bandpass signals', The Bell System Technical Journal vol. 56 Number 4, April 1977" and some other publications by the same author in the same journal. Recently these techniques have been exploited in 'zepoc' algorithms for low power hifi class D amplifiers and the 'click modulation' scheme. But there were also publications which were in doubt that a real valued signal can be reconstructed by its zero crossings. Sadly, my mathematical background is not sufficient to follow the arguments. But nonetheless zero crossing algorithms and nonuniform sampling are very promising fields. Cheers Detlef _______________________________________________ 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.
