On 16 Sep, 2012, at 16:30 , Poul-Henning Kamp wrote: > In message <34d5c3ce-6b3d-4944-996a-7637373b2...@gmail.com>, Dennis Ferguson > wr > ites: > >> I'm not sure there could be a difference between the goals of >> frequency accuracy and time accuracy that would effect that time >> constant.
Note that the "that time constant" referred to here, the topic of the message I was responding to, was explicitly a PLL time constant. If you have decided to use a PLL as your control discipline I think you end up with the same time constant whether your goal is accurate frequency or accurate time since, with a PLL, these end up being the same problem. > It does. > > A PLL more or less corresponds to an "PI" regulation, where a FLL > only needs to have the "I" term. > > Because you don't have the interaction between the P and I terms, > the I-timeconstant can be longer. This sounds right. As I said, if you pick a control discipline other than a PLL, as might be advantageous to do if your concern is solely with accurate frequency, then the optimum might be different. If you are using a PLL in both cases, however, then the problems are essentially the same. Dennis Ferguson _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.