[Tinyos-help] Drift - Time Synchronization

[Somnath Mitra]

Hello Zainul,

Thanks for your reply. You said that the freq error (worst case) for the 32
Khz crystal is 40 ppm. What if we use the internal DCO ? will our internal
freq error go up ?

Thanks,

Somnath

On Sat, Oct 18, 2008 at 3:35 PM, Zainul M Charbiwala <zainul at ee.ucla.edu>wrote:

> Hi Somnath,
>
> The main clock on the Telos motes runs on an internal DCO which has a
> lot of frequency error (could be on the order of 10%), unless the
> error is corrected through periodic recalibration with the crystal.
>
> I believe the timers are run off the 32KHz crystal in TinyOS, which
> would lead to a worst case of 40ppm freq error.
>
> The clock drift is essentially (in sec), drift =
> (time_since_last_sync)*(freq_error_in_ppm)/1e6.
>
> This means that if you don't resync periodically, your clock drift
> could be unbounded.
> Hope this answers your question.
>
> Zainul.
>
> On Sat, Oct 18, 2008 at 1:17 PM, Somnath Mitra <shomnat at gmail.com> wrote:
> > Hello ,
> >
> > People who have worked on time synchronization, can anyone please tell me
> > that -
> >
> > Can we say that there is a maximum upper bound on the amount of drift of
> the
> > clocks of Telos like platforms ?
> >
> > Thanks,
> >
> > Somnath Mitra
> >
> > _______________________________________________
> > Tinyos-help mailing list
> > Tinyos-help at millennium.berkeley.edu
> > https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
> >
>
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