Solution to N810 GPS problems?
February 4, 2008
I’ve been playing with a possible solution to the time-to-fix problems of the Nokia N810 GPS, and it looks good: Getting a fix used to require 5-15 minutes even in very good conditions. Today I have experienced fix times between 30 seconds and 3 minutes — even from the window which was previously almost impossible.
The solution? Don’t have a 86400 second error in GPS time keeping.
I’m not kidding: there’s a leap year bug in gpsd which makes it add an extra day to all timestamps between Jan 1st 2008 – Feb 28th 2008. All gps-related code apart from gpsd is closed source so I can’t tell for sure, but I’m guessing this false time is used when the gpsdriver is initialized with the “last known position data”.
The evidence is just anecdotal, and this could be just a fluke. If anyone else wants to try and confirm, my patched testing packages are available. The first fix after installing should still take a long time, but I expect the following fixes to be faster. Please comment if you do any tests.
EDIT: Nokia osso-gpsd maintainer says this in the bug:
The analysis that the leap year bug would affect fix times is wrong.
Based on the comments here I’m assuming it’s not just placebo that we’re all seeing, so I’ll have to investigate a bit further.
EDIT 2: Well, not only was I probably wrong, but the package prevents system upgrade. I’ve removed the patched packages and have original 1.0-25 up, please install that if you tried my patched version.