[GPS_Standard] Question about MonTrol statistics calculation

[Chris Howard w0ep]

I'm trying to write a perl script which
monitors the output of my GPSDO and calculates
the statistics on the fly as seen in the
MonTrol statistics window.

I have a formula for variance and standard deviation
and the numbers I get seem sensible.

Roughly what I am doing is getting the hex value
from the GPSDO serial port string.  I add that
to 159973376 so as to normalize it at 160,000,000.

Then I'm calculating a rolling variance and SD using
those numbers in the neighborhood of 160,000,000
and 'n' being incremented at each new line
from the serial port.  That gives me a variance
somewhere around 4 or 5 and an SD of around 2.
How do I then get the 10^-9 -ish figure out of that
as I would see in MonTrol?

Thanks!

Chris
w0ep