Midi Merge Technique? (Jitter)

[Rene Schmitz]

At 17:38 23.01.00 +0100, Magnus Danielson wrote:

>One of the things which limits the system is the tempo changes, since this
>put the requirements for quick changes and this forces the PLL responce time
>down and thus the filter cut-off up. This means lower jitter attenuation.
>Most PLLs are 2-poles and occasionally you see 3-poles. There are reasons for
>that.

I would expect to find the pulse within a small time-window. Maybe 1-2ms
from where I'd expect it ideally. If it appeared much sooner or later I'd
say that we either have a "ghost pulse" by external fields, or (and more
probable) the tempo has changed. Now in software this would be easy, set up
a PLL to do the smoothing action, and if there is a too large "jitter" due
to the changing frequency, you'd use the incoming pulses directly. Wouldn't
this be similar to a nonlinear action of the filter? 
For a hardware solution I think of demodulating the frequency of the input
pulse train, and using a differenciated version of that signal to judge if
its jitter or tempo change. Rising the corner frequency of the loop-filter
in the latter case to make the loop faster.

Bye,
 René





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