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

J. L. Trantham jltran at att.net
Wed Jan 25 23:35:23 EST 2012

I'll have to get one of those 'round TUIT's' one of these days and check

The interval clearly is not something near .8 sec and, likely, truly 1 PPS
along with the 10 MHz output.  However, by time nut standards, I have more
work to do.


-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Scott Newell
Sent: Wednesday, January 25, 2012 9:57 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Determination of the placement of the first pps

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 

time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to
and follow the instructions there.

More information about the time-nuts mailing list