By the way, the HP5370B has a OCXO, not TCXO. It needs a while to become stable, but should be quite consistent after that.
On Thu, Nov 3, 2016 at 4:50 PM, Nick Sayer via time-nuts <[email protected] > wrote: > I’m going to try and describe my thoughts, but it may not come out as > “right” as some others here can do. Still… > > One problem you’re going to run into if you go down the road of attempting > to PLL one thing to another is that you have to find a balance between > phase control and frequency stability. > > You’re going to always be reacting to the phase drift of your disciplined > device. Your “knob” for doing so is to adjust (probably in steps) the > frequency. If your PLL is very “twitchy,” then you’re going to move that > knob very quickly and firmly, resulting in very tight phase control, but a > frequency that, at least over a short term, will jump around a bit. > > By contrast, if you are very reluctant to move the “knob,” then you’re > going to move it so slowly that by the time you have a meaningful effect on > the phase, the phase will have drifted quite a bit. That said, your > movement of the frequency knob will be so slow that the frequency stability > would be much better, at least over the short term. > > In essence, this is choosing the PLL time constant. How you do so depends > on the behavior of your device as well as the stability you desire from the > output. > > > On Nov 3, 2016, at 5:20 AM, Peter Reilley <[email protected]> > wrote: > > > > I am the proverbial man with too many clocks and I don't know what time > it is. > > To correct this situation I have decided to calibrate everything. > > > > I have a HP 5370B, a HP 6370A, and a HP 5328A all with the TCXO option. > I also > > have some TCXO modules. I figured that I would calibrate them against > my Trimble > > Resolution T GPS receiver. > > > > I put the 1 PPS signal in one channel of my scope and one of the 10 MHz > TCXO > > signals in the other channel and look at the phase relationship. The > TCXO's are > > already close enough that I should not be out by more than a fraction of > a waveform. > > I understand that I have to deal with the 1 PPS without sawtooth > correction. > > > > I expected to see the 10 MHz signal bounce around but not move more than > 1/2 > > of a wave length. Instead I see the 10 MHz waveform appear steady for > a few seconds > > then jump a significant portion of the wave. The jump is too much to > be confident > > that I have not slipped one cycle. > > > > Can I do what I am trying to do or am I missing something? > > > > Pete. > > > > _______________________________________________ > > 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.
