[time-nuts] GPS with PPS

Hal Murray hmurray at megapathdsl.net
Wed Sep 30 18:27:07 UTC 2009

> Does anyone know if any of those all-in-one hockey puck GPS receivers
> put out PPS on the serial cable? The type that has the antenna and GPS
> together, with a serial cable hanging off of it. I'm thinking about
> using one for a timing project. The more sensitive, the better, as it
> will be used indoors. 

The Garmin GPS 18 is popular with the NTP crowd.  A year or two ago it was 
replaced/upgraded with the 18x.

There are 3 versions.  One for USB (no PPS), one with bare wires (needs 5V 
and has PPS), and another with a car adapter.  Be sure to get the right one.

Mine is inside.  It works most of the time.

I've seen it report time that is off by a second.  I think that only happens 
when it is recovering from not-enough-satellites, but I don't have good data.

If you want another option, the best alternative I have seen is the GlobalSat 
MR-350.  It's a through-hole mount rather than a magnetic mount.  It comes 
with a PS-2 style connector.  (You can chop it off.)  The PPS is only 1 
microsecond wide.

These are my opinions, not necessarily my employer's.  I hate spam.

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