[ntp:questions] ntpd on embedded risc

cnm3332 at gmail.com cnm3332 at gmail.com
Thu Feb 19 21:14:01 UTC 2009

On Feb 19, 1:56 am, David Woolley
<da... at ex.djwhome.demon.co.uk.invalid> wrote:
> Hans Jørgen Jakobsen wrote:
> > precision=-7 is not that spectacular.
> > Are there other options for clocks on the board?
> Exactly, although the convergence time requirements are also unrealistic
> for ntpd.
> precision -7 tends to suggest the hardware is using a 10ms clock with no
> interpolation, which means that times read by the application, and in
> ntpd offsets, have a built in 10ms peak to peak error term.
> Once converged to a network source, one would expect up to an order of
> magnitude better setting for the time than indicated by the offset, but
> you will still only be able to read it to 10ms.  I'm not sure that there
> will be enough noise in the SHM PPS readings to dither them
> successfully, so there is some risk that it will hop between two 10ms steps.

Hm, so perhaps hardware is not ideal for NTP server then.  I think I
start looking at other embedded systems then, maybe sticking with
x86 like via eden or something.  Is there anyway I can know accuracy
of clock?  People have recommendations on what small systems
I should try?

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