[time-nuts] Checking Time difference between PCs

Scott McGrath scmcgrath at gmail.com
Fri May 24 09:03:19 EDT 2013


PC clocks are cheap and not intended to be accurate,  it's why time synchronization is one of the things managed when a windows machine joins an AD domain.  As AD uses multi-master replication accurate time stamps are required for normal operation

Best recommendation is to run NTP not SNTP as NTP compensates for the clock skew and applies corrections for the clock characteristics

Sent from my iPhone

On May 24, 2013, at 1:04 AM, Chris Albertson <albertson.chris at gmail.com> wrote:

> Run NTP on each PC.  The use the ntpq command to print out a nice table.
> Simply using NTP on Windows will force the clocks to be without about .002
> seconds.   That is about as good as you can do using Windows.    BSD or
> Linux can get about 2 uSec.  NTP software is free and not hard to set up.
> The "billboard that ntpq prints out shows clock offsets on milliseconds (to
> .001 mSec) as well as "jitter" in the same units
> 
> 
> On Thu, May 23, 2013 at 2:26 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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> 
> 
> -- 
> 
> Chris Albertson
> Redondo Beach, California
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