[time-nuts] Another "atomic" clock question

[Hal Murray]

> I am trying to understand how this is done.  Should I ever get a rubidium
> standard, I'd want to check its calibration, and that's not a trivial
> exercise. 

If you assume your rubidium is stable, then it's pretty easy to check and/or 
calibrate.

The trick is that you need someplace to stand.  A PC running ntp is good long 
term.  There is a tradeoff between good and long.  Good is ambiguous, but 
both how-good is your PC clock and how good/accurate a measurement do you 
want are appropriate.

Probably the simplest way is to get one of tvb's preprogrammed PICs.
  http://www.leapsecond.com/pic/picdiv.htm
  http://www.leapsecond.com/pic/picpet.htm

One approach is to use a picDIV to make a PPS and then monitor that.

If you have Linux, you can feed the PPS to a serial port.  My hack for 
counting 60Hz will work fine at 1 Hz.
  http://www.megapathdsl.net/~hmurray/time-nuts/60Hz/60Hz.py

Another approach is to use a picPET and connect a modem control signal from 
the monitoring PC to the Event input on the picPET.  Then the data collection 
program grabs the time, flaps a modem control signal, grabs the time again, 
then grabs the text from the picPET and logs everything.



-- 
These are my opinions.  I hate spam.