[ntp:questions] FLL instability

Mischanko, Edward T Edward.Mischanko at arcelormittal.com
Sun Jan 6 08:45:54 UTC 2013

> -----Original Message-----
> From: questions-
> bounces+edward.mischanko=arcelormittal.com at lists.ntp.org
> [mailto:questions-
> bounces+edward.mischanko=arcelormittal.com at lists.ntp.org] On
> Behalf Of David Taylor
> Sent: Sunday, January 06, 2013 2:18 AM
> To: questions at lists.ntp.org
> Subject: Re: [ntp:questions] FLL instability
> On 06/01/2013 06:29, Mischanko, Edward T wrote:
> > I have "tinker allan 7" in my ntp.conf, as recommended, but I
> notice that the frequency is adjusting wildly starting with
> polling at 128 seconds.  Is something wrong with the way FLL is
> implemented?
> []
> Where is this recommended?  URL, please.  I've never had the
> need to use
> this tinker myself, so I wonder whether it's some situation
> which
> doesn't apply to me.
> --
> Cheers,
> David
> Web: http://www.satsignal.eu
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[Mischanko, Edward T] 
This was recommended to me on this list several months ago.  I am running my windows client on a corporate LAN and it was suggested that the PLL would not correct fast enough at polling intervals over 128 seconds.  The problem I am seeing is that when FLL is implemented the frequency swings excessively and the offset does not train toward zero.  This would not be needed for setups using GPS/PPS reference clocks.


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