[ntp:questions] Re: Good GPS for attic?

Chris Malcolm cam at holyrood.ed.ac.uk
Sat Feb 12 23:54:35 UTC 2005

"David Schwartz" <davids at webmaster.com> writes:

>"Ivor Jones" <ivor at despammed.invalid> wrote in message 
>news:374g4cF5b3e1sU1 at individual.net...

>> Ok, but it does seem to me to be a case of using a sledgehammer to crack a 
>> walnut..!

>    Not at all!

>> GPS provides for so much more than merely a time server.

>    Nevertheless, it is now the world standard for time synchronization.

>> If it's experimentation you want, it's possible to modify one of the many 
>> off-air MSF or WWV etc. clocks and use that to set a PC's time by use of 
>> some very simple software and a minimal hardware interface. I still have 
>> the details somewhere of one I had to keep an old DOS PC synchronised to 
>> MSF.

>    Which of these works everyplace you have a view of the sky and can keep 
>time to an accuracy of better than one microsecond?

While GPRRs have to keep time internally to within several
nanoseconds, few of them bother trying to report it to the user with
that degree of precision. For a start it's impossible over an RS232
serial link. Up to a second out is not uncommon. You'd get more a more
accurate time fix with a program that listened to radio time pips over
a microphone!
Chris Malcolm cam at infirmatics.ed.ac.uk +44 (0)131 651 3445 DoD #205
IPAB,  Informatics,  JCMB, King's Buildings, Edinburgh, EH9 3JZ, UK

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