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Old August 6th 17, 07:09 PM posted to uk.radio.amateur,uk.rec.models.engineering,rec.radio.amateur.homebrew
Brian Reay[_5_] Brian Reay[_5_] is offline
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First recorded activity by RadioBanter: Aug 2013
Posts: 393
Default A mechanical phase locked loop!

On 06/08/2017 18:37, Gareth's Downstairs Computer wrote:
On 06/08/2017 17:18, rickman wrote:
Gareth's Downstairs Computer wrote on 8/6/2017 5:26 AM:
On 05/08/2017 23:25, rickman wrote:
You seem to be completely misunderstanding the operation of the Shortt
clock. The slave pendulum has no need for correction of circular
error.

I'm sorry, but you totally misunderstood what I was saying, which was
that because all pendulums exhibit circular error, when the hit occurs
in the hit and miss synchroniser and foreshortens the swing, then, for
that half-cycle, and only that half cycle, the frequency is
changed, as it must be.

Just as in the electronic PLL, instantaneous changes of phase have
instantaneous changes of frequency, no matter how short lived,
associated with them.


What you say about frequency vs. phase is true and how the Shortt
clock adjusts phase, but it has nothing to do with circular error of
the pendulum. The correction of the phase is from the added spring
resistance shortening the time as well as the travel of the pendulum.
The fact that the swing is shorter and the second order circular error
will create a tiny error in the timing is pretty much irrelevant. The
real change is from the added spring constant changing the first order
effect in the pendulum equation. The coefficient of the gravitational
constant is effectively changed by the spring.

Is that more clear?


You continue to misunderstand. Any pendulum swinging with circular error
speeds up for shorter amplitude; speeding up means increased frequency.
Therefore, for the half cycle inwhich there is a hit, a shorter
amplitude and hence instantaneous higher frequency exists.



Nothing in any of rick's posts he does understand the above, or anything
else. Plus, what you have posted is exactly what I explained to you
earlier.

It is clear you are on the edge of resorting to your normal abuse.