[GPS_Standard] Self Test experiment with strange result

[Dimitri.p]

I took the 10 Mhz output from the board, run it through a divider 
chain (74HC390s) to end up with 1Hz and used that  to feed the 1PPS input .

Montrol reports
Avg frequency offset -3.29e-10
Std Dev       1.46e-08
Min -3.12e-08
Max 2.50e-08

These values are in the same neighborhood of what I get using the 
1PPS from the GPS.

On frequency counters when you measure the counter's own timebase you 
end up with 10 and as many zeroes as can fit on the display.

I was expecting values in the e-12  (or better) neighborhood.

The idea that there is a frequency "offset" when the 1PPS is derived 
from the same 10MHz being measured  doesn't make much sense at the moment.

Can anyone shed any light on this ?


Dimitri


Dimitri