[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.
--
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