[time-nuts] How to get PPS from ublox mini-PCI GPS to APU2 SoC serial port for ntpd

Attila Kinali attila at kinali.ch
Tue Aug 23 03:38:19 EDT 2016

On Tue, 23 Aug 2016 07:11:23 +0000
"STR ." <strykar at hotmail.com> wrote:

> > Unless time-nuts levels of precision/accuracy are required, an APU is good enough and an easy solution. If you go for time-nuts levels, then I would question the use > of ethernet long before I question the hardware platform.
> Not even ethernet with hardware PTP implementations, admittedly I haven't seen a NIC for sale with it?

Most GBit NIC have hardware timestamping these days. Though I don't know
if whether the APU NICs do.

But even with hardware timestamping, you will not get to time-nuts levels,
which are lower than you think :-)
With standard networking equipment, you will not get below a 1-100us
uncertainty. Although this is quite good and usually enough for most
people, it's not time-nuts. A time-nuts strives for low-ns or even sub-ns
level of synchronization. With the proper equipment you can achieve
better than 10ps within a building.

				Attila Kinali

It is upon moral qualities that a society is ultimately founded. All 
the prosperity and technological sophistication in the world is of no 
use without that foundation.
                 -- Miss Matheson, The Diamond Age, Neil Stephenson

More information about the time-nuts mailing list