Chris wrote on 8/5/2017 9:34 AM:
On 08/05/17 09:45, Jeff wrote:


Rubbish, the function of a phase locked loop is to keep the phase of the
2 signals the same, within the constraints of the loop filter.

The clock *never* achieves this, it is open loop and applies a 'kick' to
one pendulum the amplitude of which is NOT related to the difference in
phase of the 2 pendulums.

A fixed kick is given without any knowledge that it will be of the
correct amplitude to achieve an in phase or near in phase condition.
There is NO feedback of an error signal that relates to the phase
difference between the 2 pendulums.

The only time phase comes into the picture is the timing of when the
'kick' is given, so as not to disrupt the normal swing of the pendulum,
and whether or not to give a kick at all.


Exactly. The control is single path, master to slave, with no feedback
to the reference, making it an open loop design. The master has no
knowledge of the state of the slave at any time.

You aren't making sense. The reference is never adjusted in a PLL. That's
why it's the *reference*.


In a pll, there is continuous feedback from the vco to the phase
detector, closing the loop and keeping the phase offset constant,
The phase is continuously updated every cycle, whereas the Shortt
clock can have significant accumulated error in the time between
corrections...

There is no requirement in a PLL for continuous action or even frequent
action.

--

Rick C