[time-nuts] Low-long-term-drift clock for board level integration?

Dennis Ferguson dennis.c.ferguson at gmail.com
Mon Feb 20 06:20:16 UTC 2012

On 19 Feb, 2012, at 21:08 , Bill Woodcock wrote:
> It's my assumption that some of them will be able to get enough GPS signal (or GPS via a GSM BTS, as we also have a Sierra Wireless GSM chipset onboard) and would thus be able to act as Stratum 1 servers for the others.

In the US I suspect all GSM base stations have GPS available (E911 support
generally requires it), but I think you may find that in many (most?) other
countries the GSM BTS gear has no idea what time it is.  GSM doesn't require
the time synchronization (it requires frequency, but they can often recover
that from the tail circuit connecting the BTS to the network), so in many
places they do without GPS either to save money or because the carriers are
subject to regulatory requirements to avoid allowing the country's
telecommunications facilities to become dependent on GPS (I assume because
their regulators don't fully trust the owners of GPS)…

GPS can sometimes work under non-optimum circumstances, but it sounds like
you have run out of fallback options apart from trying to advance the state
of the NTP art.

Dennis Ferguson

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