Garmin GPS

There is an article in PBO this month by the service manager for Garmin who says if you leave your GPS switched off for more than 24 days, it can lose its almanac data and subsequently take up to two hours to find itself again on switching back on.

I think this happened to me in Plymouth because it was Tuesday before I was certain of my location.

DM

Nothing to do with the copious amounts of alchohol consumed then?

John (sober as a judge) "Cookee" Cooke!

are you sure that was not alcohol induced loss of direction???

seriously though,

All SV almanac data is updated every 6 days and is valid for upto 6 months, each SV sends data for all SV's.

Broadcast data is updated every hour and valid for 4 hours

each SV also sends only its own ephemeris data

this is why if you travel more than a few hundred miles the almanac data will be innaccurate and the GPS will not get an immediate lock, depending on the cylce of 30 mins you may have to wait 29 1/2 for a fix!!