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

Brad Knowles brad at stop.mail-abuse.org
Thu Mar 10 02:52:13 UTC 2005


At 6:26 PM -0800 2005-03-09, roy wrote:

>  Isn't this a bit misrepresented?  The way I read his web page, he
>  replaced the standard, 39 cent crystal with a $1,500 rubidium frequency
>  standard.  No wonder it keeps time so well!

	No, the real key to PHK's work was taking one of the most 
accurate off-the-shelf/kit GPS units designed to provide accurate 
time, combining that with a host that had very low latency to 
servicing the necessary interrupts, and only then did he add the 
Rubidium clock.  He would not have lost too much by going with an 
OCXO or even a TCXO.

	If you want that same level of accuracy and precision in a 
commercial unit, you probably won't be able to get it.  If you can, 
you'll spend enough money that you could have bought at least one 
decent car or made a down payment on a house.

-- 
Brad Knowles, <brad at stop.mail-abuse.org>

"Those who would give up essential Liberty, to purchase a little
temporary Safety, deserve neither Liberty nor Safety."

     -- Benjamin Franklin (1706-1790), reply of the Pennsylvania
     Assembly to the Governor, November 11, 1755

   SAGE member since 1995.  See <http://www.sage.org/> for more info.



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