[time-nuts] Timing performance of servers

Bob Camp lists at rtty.us
Thu Oct 25 12:57:11 EDT 2012


Hi

If: 

1) You are in a reasonable location (good sky view)
2) Don't have a great long cable run (< 50')
3) Are only after NTP time

Then, you can get away with a pretty simple antenna. I likely won't last as
long as a better one out in the weather though. If you shop the auction
sites you can get reasonable antennas (Lucent / Trimble / Syneregy)  for <
$30. 

Bob

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Sarah White
Sent: Thursday, October 25, 2012 12:44 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Timing performance of servers

On 10/24/2012 6:47 PM, Magnus Danielson wrote:
> Fellow time-nuts,
> 
> When spending time on a conference last week, I heard one interesting
> comment that they lost data due to bad timing on their Windows servers.
> 
> Now, I know that the standard Windows uses SNTP in order to achieve the
> goal of having the timing of the machines sufficiently aligned to allow
> Kerberos authentication. SNTP suffice for that, as it needs to be a
> handful of minutes in line.
> 
> If you need better performance than that, you should use NTP (and then
> download and install Meinbergs Windows-client for NTP).
> 
> Then again, I would point out that for this type of data, it would most
> probably be better served on a Linux box.
> 
> What should be a nice wake-up call for them would be a summation of how
> different strategies would give them clock precision of sufficient
> grade. So, does anyone know of such measurements presented anywhere?
> 
> There are bits and pieces, but the ideal for this case would be if they
> where collected in one page/paper.
> 
> This is an awareness thing, so that people can do a little more
> well-informed choices.
> 
> Cheers,
> Magnus

1)

Thanks magnus. This is something I'm quite interested in:

I'm not the only one doing testing for Microsoft NT 5.x and higher
against NTP-type synchronization. It's actually high enough quality such
that a Windows server running NTP with a refclock provides significantly
better time than the public NTP servers.

Here are a few writeups I've been using for reference, and I've been
testing and duplicating some of the listed configurations, hoping for my
own writeups:

http://www.satsignal.eu/ntp/NTP-on-Windows-Vista.html (basic timing)

http://www.satsignal.eu/ntp/NTP-on-Windows-serial-port.html (connected
to refclock, timing was better than 50 microseconds jitter, averaging
less than 10 microseconds)

Am actively in the process of getting everything to replace my own
"navigation" GPS refclock with a timing mode one. At this point I just
need to find a good antenna...

2)

... Changing subject slightly:

Regardless of if I run linux vs bsd vs windows (will be testing multiple
configurations of each, and doing writeups over the next few years as I
test more and learn) I'll need a good external antenna for the new GPS
I'm going to run.

Anyone think I can get by with anything cheaper than a symmetricom
58532a antenna? I can probably get one (used) for less than $50 on ebay,
but I'd really prefer to source something more entry-level for closer to
$5 or $10 if possible. Any suggestions?

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