[time-nuts] How close can you trim a Cs?

John Ackermann N8UR jra at febo.com
Wed Mar 9 12:48:34 EST 2005

Chuck Harris wrote:

> Also, at 2ns, your counter probably isn't high enough resolution to do a 
> good
> job with a 1 second gate.  Up your gate to 100 seconds, and it will quiet
> things right down, and your ability to see small parts in 10E13 will vastly
> improve.
> The reason I say this, is a counter with a 2ns resolution will have biases
> in its timing that are a significant portion of that 2ns.  These
> biases will change with temperature/voltage, etc. And will skew your record
> even after extensive averaging.  (eg. 100*(f(t) + bias)/100 = avg(f(t)) 
> + bias)
> -Chuck

Again, sorry for being unclear in my other message -- I'm measuring the 
time difference between two 1pps signals, and looking for a change in 
that difference over time to determine the offset, so there's no gate 
time involved.  I'm averaging 100 of those readings to generate each 
line of logged data, then plotting that data to show the change over time.


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