[ntp:questions] ARRGH!!! I woke up to a 50 SECOND clock error.

David J Taylor david-taylor at blueyonder.co.uk.invalid
Thu Mar 15 08:09:13 UTC 2012


> Hi David,
>
> I really appreciate all these suggestions you shared, as well as past 
> ones.

Based somewhat on been there, done that!

> If I decide to revamp my network, I'll probably put some of them into 
> use.  However, that's not really practical right now.  All the 
> networking gear is in the basement and all the PC's are upstairs.  I've 
> already spent 2 months working on this GPS stuff and ignoring some other 
> things I need to be doing.  I think I'm just going to focus on getting 
> the Sure board up and running on a time server when it comes and, 
> perhaps, use my BU-353 as a backup time source, and use the internet 
> servers as a third level backup source.  Most of the time, I won't care 
> what they're doing  Hopefully, I can spend less time thinking about time 
> and just know that my PC's clocks are right.  Regardless, I'm going to 
> continue to have an interest in the topic and have enjoyed all the 
> discussions and learning that have occurred.  It's just that I have to 
> do at least a few other things besides this.
>
> Sincerely,
>
> Ron

Yes, sensitive those these new GPS receivers are, the basement may not be 
the best location!  <G>  Be certain to get the Sure antenna in a good 
location - it's likely sealed for outdoor use such as stuck to a car roof.

I do see quite a wide variation in performance over Wi-Fi - I have two 
permanent PCs (Molde and Puffin) and two temporary PCs (Bergen and 
Mercury) connected at the moment, and averaged jitter varies a lot:

1.0 - 4.3 ms - Molde
1.1 - 2.1 ms - Puffin
1.3 - 3 ms - Bergen
4 - 12 ms - Mercury

  http://www.satsignal.eu/mrtg/performance_ntp.php

They are all synced to a Stratum-1 FreeBSD server showing microsecond 
jitter, running the same NTP, with the same configuration.

Cheers,
David 



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