On Feb 12, 2011, at 11:11 42PM, Randy Bush wrote: >> Your suspicion may be accurate and accidental. I rented a car in San >> Diego the other day -- there was a sign warning that the key fob might >> not work within 5 miles of the port -- San Diego has a major Navy base >> -- because of interference from shipboard electronics. > > same time, my phone's gps claimed accuracy to 700m in the 10 miles from > san diego airport. that is not a lot of good for nav. luckily i used > to hang down there in the late '70s and early '80s so kinda knew my way > around. > That sounds like it didn't have a GPS fix at all, and was instead using cell site proximity location. (I didn't check my phone's GPS; my Garmin unit had no trouble.)
--Steve Bellovin, http://www.cs.columbia.edu/~smb