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.
