[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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