For test purposes I've occassionally set the time server polling
routine to once a day and seen 20 minute errors on delinquent PCs.
Other PCs might stay within a minute.
1 min per day is 694 ppm
20 min per day is 13880 ppm
ntpd calls the crystal inaccuracy drift. ntpd can't handle a clock
Charles S. Osborne said the following on 12/19/2006 09:02 PM:
I have a query. Does anyone have a favorite network time sync test software?
Here's my situation. Being at a radio and optical observatory, most
everything we do has varying degrees of time stamp criticality on the stored
data.
I could be talking a lot of hot air, so please forgive me, but I've
had a thought: if PCs still use a Real Time Clock chip, could a hardware
modification be done to give them an accurate clock frequency, rather
than relying on whatever cheap crystal is installed on the mother board?
Maybe one
Peter Vince said the following on 12/20/2006 10:11 AM:
I could be talking a lot of hot air, so please forgive me, but I've
had a thought: if PCs still use a Real Time Clock chip, could a hardware
modification be done to give them an accurate clock frequency, rather
than relying on
My information could be out of date, but in the past, the realtime clock only
set Windows on bootup. During run windows kept time off the bus crystal (hence
the sensitivity to interupts)
No matter how cheap, only a defective real time clock will err anything close
to 1 minute/day, normal
The Timer/Clock interrupt is IRQ 0 no other interrupt has a higher priority,
therefore this interrupt is rarely missed. If it were missed then interrupts
would have to be turned off longer the 110ms (2 times the clock rate) which is
an enormous amount of time and due no doubt to an improperly
Lots of good info as always from this list.
I probably should mention what some of these PCs are doing.
Someone asked about the telescope control PCs. The 26m dishes have their own
dedicated GPS receivers for their local time standards. Those do the
celestial navigation and tracking via their
] [mailto:[EMAIL PROTECTED] On Behalf
Of Charles S. Osborne
Sent: Wednesday, December 20, 2006 2:30 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] PC clock comparison software?
Lots of good info as always from this list.
I probably should mention what some
I have a query. Does anyone have a favorite network time sync test software?
Here's my situation. Being at a radio and optical observatory, most
everything we do has varying degrees of time stamp criticality on the stored
data. While I could get obsessive compulsive and try to get everything
For the 2K/XP machines, ditch the built-in windows time sync and get NTP for
windows, also probably want to use their front-end app... It's free... I
think that will solve a majority of your problems. It allows for detailed
logging (at least the *nix version does).
never know and I doubt they care.
Jack Hudler
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf
Of Charles S. Osborne
Sent: Tuesday, December 19, 2006 8:02 PM
To: Time-Nuts
Subject: [time-nuts] PC clock comparison software?
I have a query. Does anyone have
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