[time-nuts] Why are 1PPS signals so skinny?

Azelio Boriani azelio.boriani at screen.it
Mon May 14 17:03:31 UTC 2012


I thought it was only standard practice, now I see that there are standards
and requirements too.

On Mon, May 14, 2012 at 6:33 PM, <bg at lysator.liu.se> wrote:

> Mark & Azelio,
>
> Or even 10V into 50ohm, 20us... See figure 3-4 in ICD-GPS-060.
>
>    http://www.navcen.uscg.gov/pdf/gps/ICD-GPS-060B.pdf
>
> More modern 3-5.5V into 50ohm, 20us.
>
> http://contracting.tacom.army.mil/majorsys/jab/DAGR%20Interface%20Specification.pdf
>
> Above are two standards demanding short skinny 1PPS pulses. Are there any
> other standards with distinct shape requirements on 1PPS pulses?
>
> --
>
>   Björn
>
> > Feed a 5V 1Hz square wave into a 50OHM load and look at the power drain.
> > Do
> > the same with a 100uS pulse and smile at the difference.
> >
> > On Mon, May 14, 2012 at 5:23 PM, Mark Sims <holrum at hotmail.com> wrote:
> >
> >>
> >> My first inclination,  if I were building a timing receiver,  would be
> >> to
> >> make the PPS output a nice,  symmetrical square wave.   But pretty much
> >> all
> >> GPS timing receivers output an anorexic,  dinky little heroin addicted
> >> supermodel sized pulse (from 1 to 150uS wide is typical).
>
>
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