Hi Ok, let's try some math and see if I can do it without blinking this time….
+/-4 Hz for 6 volts is 0.66 Hz / V output is 10 MHz so 1 Hz is 0.1 ppm your OCXO is running at 0.066 ppm / V That's also 66 ppb / V 0.02 V at 66 ppb / V is 0.0132 ppb or 13.2 ppt The UT+ has a sawtooth output that's about 45 ns That's 45 ppb at one second 5 minutes is 300 seconds so 45 / 300 = 0.15 ppb or 150 ppt If it's the later clone version it might be about 1/2 of that. Are you doing sawtooth correction? Bob On Aug 16, 2013, at 11:09 AM, Bob Stewart <[email protected]> wrote: > I'm converting the code for the VE2ZAZ FLL to a PLL. I'm seeing the phase > correction change the EFC up and down about .02V to .03V over a period of 5 > minutes or so (it varies). The full range on the OCXO is about +/- 4Hz > varied by 0 to +6V, so at least this is a tiny value. I feel pretty > confident with my code at this point. I'm using a Trimble 34310-T OCXO for > which I've been able to find almost no information. Could this oscillating > phase correction be some sort of thermal oscillation? I've tried two > separate 34310s and both act more or less the same. My GPS device is > normally a UT+, but I just now swapped in an "Adafruit Ultimate GPS Breakout" > to the same effect. Is this good, bad, or indifferent for a GPSDO? I > started this project not knowing what to expect, and I still don't. > Experienced help, speculation, or even just kind words at this point would be > appreciated! =) I don't have a known good/stable reference to compare this > to. > > Bob - AE6RV > _______________________________________________ > 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.
