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.
Hal writes:
It might be possible to avoid hanging bridges by dithering
the sawtooth. I'm thinking of something like a heater under
the xtal for the GPS unit that gets driven by a medium
frequency - slow relative to the normal sawtooth but fast
relative to the PLL time constant. This somehow
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My information could be out of date, but in the past, the realtime clock only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
Hello folks,
i like to play the bad boy again: My claim is
a) that for most of us a GPSD Rb is of little to no use compared to a
good GPSD xtal oscillator
b) that it is a myth that you may use longer loop time constants with Rb
compared to a xtal oscillator
Let us first talk about b). It is
In message [EMAIL PROTECTED], Ulrich Bangert writes:
a) that for most of us a GPSD Rb is of little to no use compared to a
good GPSD xtal oscillator
... if your hold-over requirement is trivial.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
[EMAIL PROTECTED] | TCP/IP since
At 10:25 AM 12/20/2006, you wrote:
Hello folks,
The controller's task is to always pour just enough fluid from the
second pot into the first pot to keep the fluid level constant despite
the fluid lost through the small hole. One refinement of the model is
that we also consider that the amount of
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
A discussion of driving computer clocks from accurate sources recently
came up. While it's true that PCs generally use the CPU clock or the
baud rate clock for the timekeeping function, the observation was made
that it might be nice to run a standard RTC that uses a 32768 Hz crystal
from a 10
Yes, agreed!
-Ursprüngliche Nachricht-
Von: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] Im Auftrag von Poul-Henning Kamp
Gesendet: Mittwoch, 20. Dezember 2006 16:43
An: Discussion of precise time and frequency measurement
Betreff: Re: [time-nuts] LPRO-101 with Brooks Shera's GPS
Hello folks,
i like to play the bad boy again: My claim is
a) that for most of us a GPSD Rb is of little to no
use compared to a good GPSD xtal oscillator
Ulrich,
That's a rather general statement, but I understand what
you mean. Consider, instead of a bold general assertion
which can be
In the matter of lifetime (outside of MTBF issues), is it correct that
Rb has a built-in life limiting mechanism (the lamp wears out), where Qz
does not? If so, Rb oscillators will eventually fail but one might hope
a Qz oscillator may not.
Didier
Tom Van Baak wrote:
Hello folks,
i like to
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
In message [EMAIL PROTECTED], Tom Van Baak writes:
Warm-up time --
Many Rb will lock in 5 minutes, typically. Some Qz
take much longer to get on-frequency from cold start.
This can simplify the initial loop locking algorithm.
Initial capture is best done with a looser timeconstant in
Has anyone got one of these (part number KS24019 L105A) up and running?
Is a manual available?
Bill Hawkins
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Jason Rabel
Sent: Wednesday, December 20, 2006 10:58 AM
To: 'Discussion of precise time and
Tom Van Baak wrote:
Hal writes:
It might be possible to avoid hanging bridges by dithering
the sawtooth. I'm thinking of something like a heater under
the xtal for the GPS unit that gets driven by a medium
frequency - slow relative to the normal sawtooth but fast
relative to the PLL time
The phase detector itself in Brooks Shera's GPS locking circuit has
several problems:
1) There are no synchronisers so that the partial width pulse response
of the counters biases the output.
2) Possible synchronism between the (24MHz) phase measurement clock and
the time interval being
Let me add a note. The Shera controller also has a hold mode. This
mode will freeze the DAC output at its current voltage. So when its
engaged with a rubidium oscillator, your rubidium becomes a normal
unit, except it has been super tuned to UTC ! Short term specs return
to normal, etc.
Hi:
I'm looking for the subject article on crystal testing, or any other
articles on testing crystals.
This is more related to knowing if a given crystal is alive than
characterizing it, i.e. a Crystal Activity Meter type thing.
Have Fun,
Brooke Clarke
--
w/Java http://www.PRC68.com
w/o
Probably what to take this off list.
Eek screen capture. That's one of those heart stoppers on the Win9x platforms,
it's got nothing to do with Windows, it the device driver in some of those old
cards that CLI (Clear interrupts) for a long period. We had issues with this
causing Netware Client's
There was this post a while back for a RFG:
http://www.febo.com/pipermail/time-nuts/2005-October/019674.html
But I could of sworn I found a more complete pinout elsewhere. I'm about to
search through my browser history to see if I can find the other URL(s) with
info.
Jason
Has anyone got one
Brooke -
In that case why do not just use a signal generator like an 8640B with the
crystal in series with the hot lead and then the other side of the crystal
terminated in 1K or so. Then you can put a scope across the 1K resistor and
watch the scope as you tune across the suspected resonant
got a working hp 9825a that has a strip printer that works also. the printer
prints in double size instead of regular size and i have not found the command
to reduce the double size printing. would any one on this reflector know what
that command would be?
tom
[EMAIL PROTECTED]
Hi Mike:
I've received an email asking about where to purchase a crystal activity
meter and although I have a hand held unit, see:
http://www.pacificsites.com/~brooke/Xam.html don't want to part with it.
This is an older unit that uses PNP transistors. I'm now thinking about
how to build one
Does anyone by chance have a PDF manual for a Brandywine GPS-4 (not the PDF
spec sheet on their site)? Also, if it's not mentioned in the manual, what
is the power input for the unit?
I've tried contacting the Brandywine people a couple times, have not
received a reply. :(
Thanks,
Jason
I did just that to check the 50 MHz crystal in my HP 3586 and convince
myself it was not dead. The 50 MHz VCXO did not oscillate, for some
reason, and finding a replacement crystal would have been a long shot
and would have probably cost more than I paid for the instrument.
Seeing the proper
On Wed, Dec 20, 2006 at 10:58:02AM -0600, Jason Rabel wrote:
Just a heads up, if you search eBay for 'Lucent RFTG' you will see someone
has listed a bunch of the rubidium units today with BIN of $130. These are
not the previously listed RFG's. The RFTG have the built-in GPS receiver (I
think
Hi,
Tried sending it via this list, but there is a 128KB limit. Please send me
your direct email address.
73,
Bob N1VQR
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Jason Rabel
Sent: Wednesday, December 20, 2006 8:45 PM
To: 'Discussion of precise
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