[time-nuts] ntp and asymmetric delays

Chris Albertson albertson.chris at gmail.com
Tue Oct 11 21:00:19 EDT 2016

Yes, I think you are correct except in one case.   The NMEA offset may
very well be mostly because the NMEA sentence is actually "off".
Such sentences may be as much as a full second "off".   First the NMEA
standard requires only one second accuracy and also the sentence is
sent over a slow serial link along with other data and when you get it
depends a lot on what they "other data" is.  This is the reason the
GPS has a PPS.     NMEA was invented for ship navigation, not timing.

On Tue, Oct 11, 2016 at 10:09 AM, Thomas Valerio <tjv at westwood-tech.com> wrote:
> I was going to post my ntp output and ask for an opinion, then this
> discussion popped up.  It would appear that asymmetric delays are the
> exact explanation for what I am seeing.


Chris Albertson
Redondo Beach, California

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