Garmin GPS-18LVC Performance
The information presented here is collected by the contributing authors, or others, and is made available on an as is
basis. The information presented here does not constitute an endorsement or guarantee of performance by the NTP Public Services Project
Under a shingled roof / Soekris NET-4801 / FreeBSD-5.3release
Loopstats plot for a Garmin GPS-18LVC connected to a Soekris NET-4801 running FreeBSD-5.3release. The GPS was mounted approximately 12" under a shingled roof and the 4801 was sitting on a fibreglass batt, with the case cover removed, in an unheated attic crawlspace. The GPS was connnected to, and powered from, the 4801's internal serial port header. This plot is for January 1st, 2007 and was generated directly from the loopstats file instead of from periodic polls with a tool such as MRTG.
The peer summary (generated with peersum.awk) for this period is:
ident cnt mean rms max delay dist disp
GPS_NMEA(0) 5235 0.002 0.002 0.013 0.000 0.270 0.248
On a sloping roof with limited visibility / White-box P133 / FreeBSD
MRTG plot of a Garmin GPS-18LVC connected to a white-box
PC running FreeBSD 5.4. The GPS was mounted on a bracket outside a window, but is now placed on a roof, sloping at 30 degrees to the west, and it doesn't have 100% sky coverage. This plot is a snapshot of the current daily statistics for November 12th, 2007. Please note that you must subtract 20 microseconds from the plotted value. You can see the effect of the heating starting up between 06 and 07 UTC!