[time-nuts] Checking Time difference between PCs

Christopher Quarksnow cquarksnow at gmail.com
Sat May 25 23:21:39 UTC 2013


About using w32tm /stripchart and the µs resolution :
Despite RFC 1305 compliant, Microsoft w32tm is still bound to the clock
interrupt frequency fed to the processor :
http://serverfault.com/questions/488983/is-it-viable-to-use-w32tm-stripchart-to-judge-time-variance-of-two-windows-host
So if you have a Cs clock as a reference in your computer, or maybe a
PTP-based external reference, you might not benefit from the µs
resolution....

Chris


On Fri, May 24, 2013 at 3:39 AM, Bill Hawkins <bill at iaxs.net> wrote:

> Dear me!
>
> Your clock is off by four years and change!
>
> Bill Hawkins!
>
>
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of Christopher Quarksnow
> Sent: Thursday, May 23, 2013 9:06 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Checking Time difference between PCs
>
> This might do, even though I doubt the routines are using rdtsc to
> interpolate nondeterministic offset of the PIC architecture.
>
> w32tm /stripchart /computer:<target> [/period:<refresh>] [/dataonly]
> [/samples:<count>]
>
> The current time is 3/8/2009 21:05:30 (local time).21:05:30
> d:+00.0000000s o:+00.3047845s
>
> Cheers,
>
> Chris
>
>
> On Thu, May 23, 2013 at 5:26 PM, Rex Moncur <rmoncur at bigpond.net.au>
> wrote:
>
> > I wonder if anyone has suggestions as to how to check the timing
> variations
> > between two PCs that are running windows.
> >
> > The background to this request is that I am running two instances of
> the
> > Weak Signal Program WSJT on the same computer and get variations of
> +/-0.2
> > seconds.  It has been suggested that the variations might be caused by
> the
> > windows operating system.  As a check on this I am proposing to run
> two PCs
> > locked by GPS-18 USB and set by NMEATime which should show the
> difference
> > on
> > WSJT.  But is there some program that will show the difference due to
> the
> > PC
> > clocks alone? Or perhaps a program that outputs the PC time as a pulse
> on a
> > sound card so I can compare these on a CRO.
> >
> > Regards Rex VK7MO
> >
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