[time-nuts] Legal Time dissemination

[David J Taylor]

Hi Chris!

I have a week's worth of data now... Take a look at these graphics

http://www.flickr.com/photos/miguelbarbosagoncalves/8955346508/ and

http://www.flickr.com/photos/miguelbarbosagoncalves/8955346522/

One of them shows is the plot of the loopstats of my stratum 1 server. The
other one shows the offset determined every minute of their servers
compared to mine.

On 28 May 2013 16:11, Chris Albertson <albertson.chris at gmail.com> wrote:

> The "stratum 2" servers are by definition not connected to GPS.  They get
> their time from some other NTP server that is connected to an 
> authoritative
> clock which may or may not be GPS.    It looks like the "red server" has
>

I know that but I would expect good stratum 2 servers if they are keeping
their stratum 1 servers private and not available to the public.


> rather smooth swings over around a "handful" of milliseconds.   This is to
> be excepted.  It is within the normal range of what NTP does.  Perhaps it
> is a Windows PC running in some room where the temperature changes and the
> network that connects it to the strum 1 server is loaded.  I don't know 
> but
> a handful of milliseconds is in the normal range.  Yes it could be better.
>

I don't believe it is a Windows server but I could be wrong...


> Also the curve is somewhat smooth.  It does not look like noise from a 
> busy
> network.  It looks like their server really is moving around.
>

I believe they are on the same network. It looks like a temperature problem
really.

Thanks for all the input!

Kind regards,
Miguel
==========================================

Miguel,

I notice a step in the blue (ntp02) graph in:

  http://www.flickr.com/photos/miguelbarbosagoncalves/8955346508/

and I think in the red (ntp04) graph as well.  This suggests some change in 
connectivity between your monitoring PC and both servers, so perhaps a 
network change.  Unless your stratum-1 server took a 2 millisecond step, 
which seems unlikely.

Their ntp02looks well behaved, but their ntp04 is clearly not well behaved, 
and disappointing for public service.  In my own plotting program:

  http://www.satsignal.eu/software/net.htm#NTPplotter

I find it useful to be able to plot the offset versus time of day, as 
regular temperature variations tend to stand out - at least in my 
environment where the heating switches on at the same time every morning. 
For comparison on a similar time scale, you might like to look at my Windows 
LAN-synced PCs here:

  http://www.satsignal.eu/mrtg/performance_ntp.php?period=week#windows

so even if their servers were running Windows, they could be doing far 
better than that your graph suggests.  Could you plot offset versus time of 
day?

Cheers,
David
-- 
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-taylor at blueyonder.co.uk