[time-nuts] Accurate timestamping on computers (previously: For mywhole life timezones have been weird)
David J Taylor
david-taylor at blueyonder.co.uk
Sat Nov 3 15:12:39 UTC 2012
-----Original Message-----
From: Sarah White
Great, thanks for the loopstats.
For the included loopstats, I believe "Alta" was among the ones on which
you were running windows 7 + NTP... Would you mind confirming which
setting you have for your timezone? (since I'm reasonably certain I know
what the timezone menus would look like)
http://inkushi.freeshell.org/bst.png
http://inkushi.freeshell.org/utc.png
Windows has more than one entry for most UTC offsets (DST schedule
varies by hemisphere, country, some don't have summer time at all, etc.)
... so the timezone I personally have selected is the UTC option without
a summer time adjustment (never set to UTC+01 / BST)
... Also, curious what you mean when you say you have "wall clock" time
displayed (UTC internally) ... ?
--Sarah
=================================================
Sarah,
PC Alta is Win-7/64, with a GPS/PPS ref-clock using Dave Hart's
serialPPS.sys device driver. The time-zone on all my PCs is "London,
Edinburgh, Dublin", which implies GMT (i.e. UTC) in the Winter and BST -
British Summer Time - (UTC+1) in the Summer. I.e.
http://inkushi.freeshell.org/bst.png
What I mean by wall-clock time is that I have the "standard" settings in the
control panel, i.e. telling Windows that I am located in Edinburgh so that
the time displayed by normal applications alters with the season, and that
the time agrees with normal wall-clock time. This is nothing special, and
how almost all PCs in the UK would be set. I mean that I have /not/ set
"Casablanca" where there both Summer and Winter are UTC.
I did have one PC set to "UTC only" and NTP ran equally well on it. As I
mentioned, internally Windows runs on UTC, and a program can interrogate
that time. Windows also provides offsets so that UTC can be converted to
local (wall-clock) time for display within applications. NTP uses the
internal UTC time and is unaffected by time-zone or seasonal changes.
Cheers,
David
--
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-taylor at blueyonder.co.uk
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