[ntp:questions] Timing GPS recommendations

Thomas Laus lausts at acm.org
Mon Aug 20 20:35:19 UTC 2012


On 2012-08-20, unruh <unruh at invalid.ca> wrote:
>>> No The sure is 10s of ns device. Unfortunately this is useless as you
>>> cannot get the time into your computer to better than usec. The
>>> interrupts are not serviced fast enough on any PC to give better than a
>>> few us and the interrupt routines get delayed on a working system by
>>> more than that at times (eg due to disk priority, or things switching
>>> off interrupt processing).
>>>
>>> You would have to build a special board for your computer to better than
>>> usec.
>>>
I am also using a Thunderbolt with one of Ackermann's Clock-Block
boards to replace my motherboard clock.  The 10 MHz output from the
GPS receiver is divided by the Clock-Block board.  This sync's the PC
with the GPS constellation and without requiring an interrupt from the
CPU.  The installation requires removing a surface mount part from the
motherboard and a connection to the divider board.

There are ways to bypass the CPU interrupt requirements if you have
the proper tools.

Tom 

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