[time-nuts] PLL performance?

Bob kb8tq kb8tq at n1k.org
Wed Mar 22 17:57:02 EDT 2017


As others have pointed out, a control loop at 100 seconds is more a gain spec than 
an R/C time constant spec. The real issue is that you should have an integrator on 
the loop and that *is* an R/C sort of thing. It’s also likely to have a much longer time
constant than the magic number for the loop. 


> On Mar 22, 2017, at 2:24 PM, Hal Murray <hmurray at megapathdsl.net> wrote:
> attila at kinali.ch said:
>> There have been a couple of discussions about doing GPSDOs using only analog
>> components in the past. People fare more knowledgable than me have commented
>> there on what the challenges would be and how to solve them. So I recommend
>> to go through the archives and look for those discussions. They might be a
>> little bit hidden, though. 
> I think the main problem is how to build a filter with a time constant of 
> many seconds.  The better your OCXO the longer the time span you can 
> integrate over.  100s of seconds isn't an unreasonable target.
> There may be other problems.
> -- 
> These are my opinions.  I hate spam.
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