unruh wrote:
On 2012-02-24, David Lord <sn...@lordynet.org> wrote:
unruh wrote:
On 2012-02-23, Alby VA <alb...@empire.org> wrote:
On Feb 23, 4:29?pm, unruh <un...@invalid.ca> wrote:
No, that is a very typical figure for the frequency offset. Remember
that the crystals used to control the timing in computers are not
supposed to be terribly accurate. (They are chosen to be cheap, not
great).
It is because such frequency offsets exist that ntp was invented to
correct.
When you say "crystals used to control the timing in computers",
are you referring to the parts that make up my actual FreeBSD
Server (ie: Motherboard)? Or Parts in the GPS Device (ie: Sure Elec.
GPS)?
On your motherboard.
Or in the Satellites receiving the GPS signal?
I'm just trying to gauge, what hardware should be looking to obtain
to
improve that frequency offset. Or is it a moot point unless I'm going
to
invest in some high dollar atomic clock?
An atomic clock.
Or better yet, can I buy quality crystals from DigiKey and do some
soldering in whatever devices that need crystal upgrading?
No.
And why do you care? As I said this is waht ntp was invented for. It is
doing its job.
When I started using ntpd it didn't work with some of my
systems as the clocks were too far out, >> 50ppm, and/or
Do you mean >500PPM?
If you were running linux, you could use the adjtimex program and the -t
or --tick adjustment to change the tick value of your system clock.
each value of 1 adjustment speeds up or slows down the clock by about 100PPM.
You can use that to get the clock within the +- 500PPM range that ntpd
can adjust. chrony uses it automatically.
too temperature sensitive. Some of my motherboards had a
3-pin jumper already fitted so that an external clock
source could be connected.
Temperature sensitivity is usually in the "less than 1PPM per degree C"
so you would have had to be expriencing quite a heat wave (500 degrees
C) to have temperture be a factor. I suspect other things might have
been more urgent worries then.
If you're correct there is a charred cinder replying.
David
One of my desktop systems, p4-2667, has just taken two
days to get to an offset of under 2 ms after a kernel
ntpd is slow, but not that slow. Since for greater than 128ms offset it
does a step, and since it fixes things by about 1/2 per hour, half a day
is more like it to get it down to microsecond, not millisecond ranges.
change. I suspect because that coincided with the hottest
day in February since 1998. All my pcs were affected
except the one connected to PPS from a Sure GPS. The one
with an MSF source, no PPS, was also fighting to keep sync.
It sounds to me like network problems and ntp server problems were
playing a role.
David
Note that even all of the time standard labs around the world use
programs like ntp to track their frequency offsets.
And all atomic clocks have them.
_______________________________________________
questions mailing list
questions@lists.ntp.org
http://lists.ntp.org/listinfo/questions
