[time-nuts] Determination of the placement of the first pps

Scott Newell newell+timenuts at n5tnl.com
Wed Jan 25 22:57:15 EST 2012


At 09:13 PM 1/25/2012, J. L. Trantham wrote:

>Both pin 3 and pin 6 are 'high' when power is first applied.  When the unit
>'locks', both pin 3 and 6 go 'low' but pin 6 then puts out a 5 uSec wide 1
>PPS pulse, as judged by my 'calibrated eyeball' which means that I used a
>stop watch and counted the time for 10 sweeps of my scope, triggered by pin
>6 and set for 5 mSec/cm sweep.  These are, indeed '1 pulse per second'
>pulses.

I attempted to test a FE-5680A pps against the tbolt.  I had the 10 
MHz tbolt out to my (somewhat flaky) 5370A's ref in.  Here's what I 
got for 100 events, which took about 3:20 to complete:

         mean: 999.999 900 993 ms
         sdev: 253 ps
         min : 999.999 900 49 ms
         max : 999.999 901 68 ms
         evnt: 100


Now this was a few days ago and I was confused so don't put too much 
trust in these numbers.  FYI, the tbolt pps output measured as (not 
freq, not period):

         mean: 1.000 000 099 83 Hz
         sdev: 289 pHz (?)
         min : 1.000 000 099 04 Hz
         max : 1.000 000 100 62 Hz
         evnt: 100


-- 
newell N5TNL 





More information about the time-nuts mailing list