[ntp:questions] Re: Garmin GPS 18 firmware update -> 200ms offset

Patrick Klos pklos at osmium.mv.net
Mon Nov 28 21:59:43 UTC 2005

In article <20051125155350.GA27426 at s163m108.unavarra.es>,
Ulisses <ulisses.alonso at unavarra.es> wrote:
>On Fri, Nov 25, 2005 at 03:58:54PM +0100, Roman Mäder wrote:
>> thanks to all who responded. It wasn't the pps signal that had the 200ms
>> offset, but the NMEA-derived time itself. It looks like some hiccup,
>> because after another hard reset (pulling the plug) the unit is back to
>> normal operation.
>ummm... this makes me remember what happens with Garmin HVS-35:
>NMEA messages had an offset of [400, 700] ms with respect to the pps pulse!

You're not talking about some kind of "offset" field within a NMEA message,
right?  Only that the NMEA messages are coming out some time AFTER the PPS.
Keep in mind that there is no relationship between the PPS and the time that
the NMEA strings are sent over the (async) serial line except that the NMEA
messages are EXPECTED to come out BEFORE the next PPS.  Of course, that's not
always the case, but that's a different issue.  (we've seen NMEA strings for
one second not show up until AFTER the following PPS causing all kinds of

================= GPS based time synchronization solutions =================
    Patrick Klos                           Email: patrick at timegeeks.com
    Klos Technologies, Inc.                Web:   http://www.timegeeks.com/
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