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.
