I should also have mentioned that the 10 MHz output also has all the
typical GPS jitter. So suppressing it will also suppress the 200 Hz
tone. I'm assuming that this correction rate is unique to each unit.
Depending on the exact frequency of your unit's oscillator, it will
correct the signal X times per second. For my unit, X happens to be 200.
Ed
Magnus Danielson wrote:
Ed Palmer wrote:
Navsync doesn't really call it a synthesizer, they call it a
Numerically Controlled Oscillator (NCO). My tests suggest that
they're doing what others have done on the 1 PPS output - change the
state of the 10 MHz output (high to low or vice versa) on a
transition of their internal 120 MHz clock. This means that you
occasionally get a pulse that's ~8 ns shorter or (presumably) longer
than normal. My unit puts out a short pulse about 200 times per
second. Navsync has an app note where they say that for some
applications a phase-locked cleanup oscillator will be required.
This 200 Hz tone (and overtones) needs to be suppressed. The size of
it is 8/100 = 80 mUI. A 10 Hz BW with PI regulation would suppress
this with about 3 + 6 + 20 = 29 dB. This brings it from 8 ns to 280 ps.
I assume a -6 dB/Oct slope as it forms a 2'nd degree loop.
Cheers,
Magnus
_______________________________________________
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.
