[ntp:questions] Running ntpd with PPS precision signal only

Chris Albertson albertson.chris at gmail.com
Wed Feb 29 18:00:15 UTC 2012

Is the TXCO also used to clock the ARM?   If so a PPS derived only
from the TXCO does not add anything.    But if the ARm is running off
a lower quality crystal then the PPS would help.

I think the best thing is to let ntpd choose the clock. simply
configure it to use the nmea and pps and when/if one of them goes away
 It is actually pretty good at doing the right thing

On Tue, Feb 28, 2012 at 9:20 AM, alex n <alexvm22 at gmail.com> wrote:
> Hi,
> I have embedded system based on ARM and FPGA. GPS receiver is connected to
> ARM (NMEA) and FPGA (PPS). There is a TXCO on board also which is using by
> FPGA as clock. PPS passes to ARM through **FPGA so I can generate my own
> PPS' based on original PPS with high accuracy and sinchronized with UTC.
> After start PPS' is adjusted and ntpd uses NMEA and PPS' as source clock.
> So how should I configure ntpd for running with PPS precision signal only
> (for case if GPS is loss)?
> Thanks,
> Alex
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Chris Albertson
Redondo Beach, California

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