These are various notes about working with GPS.
GPS is a bit of mess. ESR has a great summary of the problems in his article Why GPSes suck, and what to do about it, which includes a good overview of gpsd. An overview of what’s going on is on ESR’S Guide to Hacking with GPS.
I was initially caught off guard by the amount of settle time for a GPS unit. Under worst conditions, it can take upwards of 29 minutes for a complete download of the almanac if you just barely missed the last window.
ESR has a beautiful reference in NMEA Revealed.