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
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