[time-nuts] GPS-18x behaving weirdly

Jim Lux jimlux at earthlink.net
Thu Mar 27 08:00:37 EDT 2014

I've got some GPS-18x LVC units i'm using for a time reference, and 
they're showing an odd behavior:  the position isn't updating.

I moved them across the US (from Los Angeles to the east coast), and 
when I powered them up here, it's returning the LA Lat/Lon (34N,118W), 
the (reasonably correct) UTC time and date, but never getting a fix.

In theory, this should be like a cold start, and in 45 seconds, it 
should reacquire the satellites it can see from scratch, but it's not.

I got one to start going by running the Garmin configuration program and 
setting the current position (not all that accurately, within 1 degree 
lat/lon), and it started running.  The other doesn't seem to want to 
come alive.

I'm assuming that it's just running the clock forward based on it's 
internal low power clock/battery.

I haven't checked for the 1pps output (no scope here, for one thing..and 
I'm not quite ready to write some software to probe the RS232 pins to 
see if it's there.

Has anyone seen a similar behavior?  I've tried the power cycling, and 
the Garmin "reset" command.  I've not done the "clear non-volatile 
memory" which makes it forget the almanac.

More information about the time-nuts mailing list