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.
