[time-nuts] GPS for Spirent Smartbits

Hal Murray hmurray at megapathdsl.net
Fri Feb 16 18:13:05 EST 2007

> I have been thinking about this... It will no work,  as GPS needs to
> be in position hold which is not compatible to mobility.... We will
> think about connecting via 3G to an NTP server... and make some tests
> to see if results have any sense... 

There are two types of software for GPS receivers: timing and navigation.  
(There is probably another one for surveying.)

The low cost units are intended for navigation.  They don't have a position 
hold mode.

I'm pretty sure the Garmin GPS-18-LVC I suggested doesn't have a position 
hold mode.  (If it does, somebody please send me a clue.)

You could also try letting your NTP server run without any clock.  Look at 
the documentation for the local refclock.  It will have some offset and some 
drift, but you can correct for that if you can get good data before and after 
a set of tests.

I'm assuming the links will be unloaded when you aren't testing.  That may 
not be true.  Or maybe you just have to work a bit harder to get some 
calibration data.

I'm also assuming the temperature is stable and the test doesn't run too long.

These are my opinions, not necessarily my employer's.  I hate spam.

More information about the time-nuts mailing list