Hi Just good old Fourier series.
Bob On Nov 17, 2012, at 9:12 PM, Volker Esper <[email protected]> wrote: > > I'm impressed - but what law is behind this? > > > Am 17.11.2012 21:26, schrieb Bob Camp: >> Hi >> >> 60 db isn't to bad a number. More or less: >> >> 100 ns -> 100 ps is 1000:1. 20 log of that is 60 db. 100 ps to 60 ps is >> about 4.4 db. That would sum up to -64.4 dbc. The main gotcha is that you >> *might* also have some 15 MHz (and higher) energy in the signal as well. >> Also phase gets into the calculation. Still, pretty close. >> >> Bob >> >> On Nov 17, 2012, at 12:50 PM, Volker Esper<[email protected]> wrote: >> >>> >>> So let's have a look into the machine... and what do we see? There's a nice >>> little Symmetrcom oven, with the sign reading "5.000 MHz" - bingo! >>> >>> May be there's a time saving way to determine the energie of the sub >>> harmonic: using my spectrum analyzer. It tells me, that there's a 5 MHz >>> subharmonic at the level of -62dBc. >>> >>> How would you have calculated the energy? What would be your ansatz? >>> >>> Thanks so far >>> >>> Volker >>> >>> >>> Am 17.11.2012 17:55, schrieb Bob Camp: >>>> Hi >>>> >>>> That's what you get if you have "sub harmonic" energy in the output of >>>> your OCXO. I'd bet you a warm glass of beer that you have a 5 MHz / >>>> doubled to 10 MHz MTI OCXO in your Z3805. If you have a lot of time on >>>> your hands, you can calculate the likely level of the energy from the >>>> amount of jitter (spacing between the two peaks) you get. >>>> >>>> Bob >>>> >>>> On Nov 17, 2012, at 11:41 AM, Volker Esper<[email protected]> wrote: >>>> >>>>> Hi, >>>>> >>>>> while playing with my recently aquired TIC (SR620) and measuring the >>>>> period time of some oscillators I discovered something I hadn't expect at >>>>> all: >>>>> >>>>> The output of my GPSDO (Z3805) writes two maxima in the period histogram >>>>> (at a spacing of 60ps). >>>>> >>>>> I didn't believe that result and assumed an inherent error in my >>>>> measuring setup or the counter itself. >>>>> >>>>> So I plugged another oscillator, the reference TCXO of my signal >>>>> generator (R&S SMX), and that result made me happy and uneasy at once: >>>>> The TCXO hat only one maximum. >>>>> >>>>> I havn't calculated the ADEV curve, yet. >>>>> >>>>> See pictures. >>>>> >>>>> Why does my GPSDO produce such a weird result? >>>>> >>>>> Cheers >>>>> >>>>> Volker - DF9PL >>>>> <DSCF1437_bbb.jpg><DSCF1439_bbb.jpg>_______________________________________________ >>>>> 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. >>>> >>>> >>>> _______________________________________________ >>>> 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. >>>> >>>> >>> >>> >>> >>> _______________________________________________ >>> 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. >> >> >> _______________________________________________ >> 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. >> >> > > > > _______________________________________________ > 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. _______________________________________________ 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.
