[time-nuts] Is it sensible to update every few seconds from NTP server?

[bjones0 at mindspring.com]

We had a presentation at our radio club several months ago on digital HF
modes, and part of the presentation was on JT65 and apparently it needs
a precise synchronized time fix on both ends for an exchange to occur.
I do not recollect all of the details that were presented, but they did
say that the default windows time keeper is not accurate enough, and
advocated installing a third party ntp client that updates (way too)
frequently.

-Brian




On Wed, 2012-11-07 at 16:52 -0600, David wrote:
> Some finicky software becomes upset if time is stepped backwards too
> far.
> 
> I have seen PC hardware clocks that drifted 30 seconds a day but that
> only matters during a restart.  The more common problem involves OS
> time drift, often amounting to seconds per minute, caused by bad
> System Management Mode code leading to lost interrupts or other
> problems.  A BIOS update or fiddling with the CPU power management
> usually fixes that.
> 
> On Wed, 7 Nov 2012 17:11:26 -0500, paul swed <paulswedb at gmail.com>
> wrote:
> 
> >Interesting I am unaware of any amateur service requiring that tight of
> >a timing relationship.
> >At least modern PC clocks do not drift that badly in a few minutes. So it
> >is pretty odd.
> >Without further detail I am at a loss for why you need to do that.
> >Maybe he is tinkering with spreadspectrum?
> >Regards
> >Paul
> >
> >On Wed, Nov 7, 2012 at 5:04 PM, David <davidwhess at gmail.com> wrote:
> >
> >> Some Windows NTP clients like Tardis can calculate and implement a
> >> clock frequency adjustment instead of stepping the clock if the time
> >> adjustment is below a specified limit.  If he was using an application
> >> that was upset by the time being stepped, then that might allow less
> >> frequent updates.
> >>
> >> If he is polling that often to maintain accurate time, then I would
> >> assume he is using a local known to be accurate NTP server.
> >>
> >> There are Windows NTP clients which will synchronize to GPS PPS time.
> >> That should be better than stock hardware and Windows can handle
> >> anyway.  Something like a Garmin GPS18 is specified to be within 1uS
> >> and has a pulse to pulse jitter in the 10s of nanoseconds.
> >>
> >> On Wed, 7 Nov 2012 21:41:36 +0000, David Kirkby
> >> <david.kirkby at onetel.net> wrote:
> >>
> >> >Someone at my radio club uses some mode of operation where accurate
> >> >time is required. He said the standard Windoze clock does not keep
> >> >sufficiently accurate, so he has software which updates from an NTP
> >> >server every 4 seconds or so. It's not exactly a denial of service
> >> >(DOS) attack, but seems almost close to it in NTP terms to me. I can't
> >> >really believe updating every few seconds is sensible myself, but he
> >> >assures me it works very well. (I'm rather hoping it does not use a
> >> >stratum 1 server!)
> >> >
> >> >I'm sure someone will say if you want accurate time on a PC, to use
> >> >some combination of GPS, rubidium or OCXO with a 1 pps pulse and a
> >> >serial port on a FreeBSD or similar computer. But that's probably not
> >> >practical if your software only works on Windoze.
> >> >
> >> >Any comments?
> >> >
> >> >Dave, G8WRB.
> >> >
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