[time-nuts] PLL Math Question
magnus at rubidium.dyndns.org
Fri Mar 14 11:42:03 EDT 2014
On 12/03/14 19:26, Bob Stewart wrote:
> Hi Magnus,
> Thanks very much for this response! It will be very easy to add the exponential averager to my code and do a comparison to the moving average. I have no experience with PI/PID. I'll have to look over the literature I have on them and relate that to what I'm controlling.
> It should be mentioned that I'm more interested in the adventure than in just copying someone else's code or formulae and pumping this out. I have an idea of how I want to do this and...
The effect of additional filtering can be a little tricky to analyze
sometimes, but the exponential averager, the normal 1-pole low-pass
filter, is however well-understood when the cut-off frequency is well
above the normal PI-loop bandwith. K*4 seems to pop up in my head.
It's a hint which comes from experience of others as well as myself.
You can also look into the Stanford Research PRS-10 manual, which also
optionally have such a filter in it's PPS slaving mode.
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