On 08/06/17 10:38, Jeff wrote:

You are making pointless distinctions. A phase locked loop is not
defined by its mechanics but by the nature of its control. The Shortt
clock maintains the relative *phase* of the two clocks by brief
adjustments to the frequency via a spring. This is controlled by
measuring the relative *phase* of the two clocks.


Wrong! It does NOT measure the relative phase, it makes NO measurement
of the phase difference. All it does is detect if there is a phase lag
of any degree. It could be a fraction of a degree or 180 degrees, the
same correction is then applied regardless.

It's that simple. You are just making things more complicated by
talking about the details of how the adjustment works and the time
function of the frequency. NO PLL can keep the two clocks perfectly in
sync.

Calling it open loop is just absurd. The loop is closed because it
*measures* the phase of the clocks and adjusts the phase according to
the measurement. It may be binary, but the adjustment is controlled by
the measurement.

Wrong again it is open loop, there is no measurement, just the same
adjustment regardless of the phase difference.

Jeff



Might be easier to define a set entitled "Locked Oscillators, of which
the phase locked loop, injection locked and hit and miss synchronised
are all members.

Are there other candidates ?...

Chris