Johan Bodin wrote:

Another alternative is Motorola Oncore UT+ which was designed specifically
for timing applications. It has a "Site Survey" function which, if started, 
calculates
the average of 10000 position measurements and then enters "position hold mode".
When in position hold mode, it delivers accurate time with as little as one 
satellite
in view. The 1PPS output is specified to be within 50ns of "true time" (GPS time
or UTC, selectable) with SA on. Now that SA is gone, the accuracy is even better
(there is always a ~30ns sawtooth error due to finite resolution in the 
software/hardware).
[snip]

I remember having read that the Oncore has been discontinued by Motorola.
I have been suggested the following GPS OEM unit as a valid (or better) 
alternative
when the primary interest is the 1PPS pulse :  http://www.laipac.com/msg4.htm

73   Alberto   I2PHD