[time-nuts] Discussion of precise time and frequency measurement

Chris Albertson albertson.chris at gmail.com
Wed Jun 29 19:11:49 EDT 2011

On Wed, Jun 29, 2011 at 3:00 PM, Bill Dailey <docdailey at gmail.com> wrote:
> The FireWire thing makes sense but is there some way to make the computer itself a slave to an external source also?

Why?   The computer has many clocks in it and they are not all derived
all from one master.  So to answer  we'd need to know which clock you
care about.  Obviously the clock to keep the current time of day can
be sync'd from s master source, like GPS or an Internet NTP server.

Maybe it's best you describe the big picture. What are you trying to do?

But if you mean the audio interface.  Then all you really need is a
stable clock on that.  There is an "elastic" buffer between the audio
interface and the software so the computer can go off and do
"whatever" for 1/10th of a second and the interface wil buffer the
data, none gets lost as long as the buffer does not overflow.

Modern CPUs do not run at a nice fixed rate. they are
non-deterministic  and might execute many instructions at once or even
out of order.   The newer Intel chips adjust their internal clock
rates to control power use and core temperature.    If you need to
sync to the external world then software techniques are used


Chris Albertson
Redondo Beach, California

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