[time-nuts] 1 PPS visual Test

Raimond Melkers Raimond.Melkers at L-3Com.com
Mon Jun 25 13:02:33 EDT 2007

and that's what I'm looking for, the actual measurement isn't that
important, the fidelity of the pulse is. The concern is, that if I over
drive the out put amplifiers of the distribution amps, I can make a VERY
ugly picture, much like taking a five MHz sine wave, and turning it into a
"dirty" semi square wave generator.


-----Original Message-----
From: Randy Warner [mailto:randy at geodetics.com] 
Sent: Monday, June 25, 2007 10:57
To: Raimond.Melkers at L-3Com.com; 'Discussion of precise time and frequency
Subject: RE: [time-nuts] 1 PPS visual Test


About the only thing you can do is put the scope in normal trigger mode,
looking for a positive going transition. If you set the horizontal sweep at
about 1mS/cm you should see the rising edge of the pulse once per second. If
you have an old scope without any storage capability the image will
naturally fade quickly. This may take some tweaking on the trigger settings
for the scope, but you should be able to find a combination of trigger
settings and horizontal division size that will work.

If your scope's trigger circuitry is stable enough you should be able to
decrease the horizontal division size so that you can get a general idea of
what the leading edge of the 1PPS pulse looks like. Depending on the
receiver it should have a very fast rise-time and be a smooth ramp.

Naturally, you will not be able to make any measurements as to the accuracy
of the pulse, but this will give you a quick health check.

Best regards,
Randy Warner
Senior Applications Engineer
Geodetics, Inc.

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Raimond Melkers
Sent: Monday, June 25, 2007 8:43 AM
To: 'Discussion of precise time and frequency measurement'
Subject: [time-nuts] 1 PPS visual

 Any suggestions on the simplest, semi inexpensive way, to be able to look
at a one Pulse Per Second wave form? It's seems that most oscilloscopes will
not let me look that low in frequency. Basically I want to know, and see if
I have a pure, clean 1 PPS waveform.


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