[time-nuts] Time syncing WiFi routers using FM radio
Hal Murray
hmurray at megapathdsl.net
Thu Nov 12 08:04:28 UTC 2015
kb8tq at n1k.org said:
> For time sync, broadcast signals are a pretty well studied topic. Sync
> signals from TV stations are a much better ...
Many years ago, I think it was late '70s, a friend showed me a blurb from
NBS. They were distributing time by piggybacking on NBC's signal. NBC had
atomic clocks at their headquarters and a collection of links from the phone
company running to all their stations. The stations locked on to the
upstream signal. So the whole system ran in lock step give or take some
propagation delay. That was needed so they could switch between local and
network signals without trashing the picture. That was long before frame
buffers.
I think it was HP that measured the signal in the Silicon Valley area. NBS
published and distributed the offset.
Does anybody remember that booklet? Did I get the story reasonably accurate?
--
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