Hi A little more detail:
What's going on is more clear if you trigger a scope on the positive edge of the 5 MHz and look at the 10 MHz. With an ideal multiplier, both the positive and negative edges of the 5 MHz should line up exactly with a positive edge of the 10 MHz. In reality, negative edge (the one not triggered) does not quite line up. It's a bit ahead (or behind) the ideal location. Since it's a small angle, the delta in phase and delta in amplitude both follow the same basic law. Bob On Nov 17, 2012, at 9:36 PM, Bob Camp <[email protected]> wrote: > 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. _______________________________________________ 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.
