[time-nuts] PPS for NTP Server - How Close Is "Good Enough"?

Sanjeev Gupta ghane0 at gmail.com
Wed Jun 10 05:24:59 EDT 2015

On Wed, Jun 10, 2015 at 12:30 PM, Ed Armstrong <eds_equipment at verizon.net>

> OK, here is the actual question. Do you think it is OK to consider a pulse
> which arise 250 ns early to be close enough? And no, I am not forgetting
> about that 3 ns, there is about 3 ns of delay added by the output circuitry.

If you know what the offset is, and it is stable, (and you have shown you
understand PCB traces, etc), I do not see how this is not OK.

For someone like me, who cannot solder, and wants something off-the-shelf,
it would be a problem. I would not know how to correct for the offset.

If you are feeding this to NTP, the driver has a fuge factor, which you can
use to consistently compensate for the 240ns (although I doubt the Pi is
stable to that level).

Sanjeev Gupta
+65 98551208     http://www.linkedin.com/in/ghane

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