[time-nuts] 1pps signal presence with no GPS signal.
javier at nebulosa.org
Thu Jul 7 05:46:01 EDT 2005
The 1pps signal on a M12+ is switchable. It can be selected to be on all
time or on only when tracking at least one satellite.
David Kirkby wrote:
> I have a Synergy GPS unit, which is fitted with a Motorola M12+
> receiver. Even if there is no signal (even no antenna connected) the
> 1pps light flashes on the front and there is a 1pps signal at the
> output connector.
> It would seem to me that if you lock a crystal/rubidium or whatever to
> a GPS system, the last thing you want to do is to steer your source
> from a 1pps signal that must be pretty inaccurate. I assume this gets
> derived from the uncompensated crystal oscillator on the Motorola
> board, and so is far less accurate than the source you are phase
> locking to it.
> I would have thought it more sensible to cease the 1pps signal as soon
> as a GPS is not locked to at least one satellite.
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