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How often do cars change position while powered down? That is, why not always (even on "cold start") use the last known position as a starting guess? How do p
by panic 10y ago
How often do cars change position while powered down? That is, why not always (even on "cold start") use the last known position as a starting guess? How do phones get GPS-quality location data even immediately after being rebooted?
- dismantlethesun 10y agoAnnectodatally, I remember that some years ago my phone used to take 5-10 minutes to find GPS whenever I asked for directions. Now adays, it's instantaneous. The software has improved dramatically, using some combination of previously saved location, WIFI triangulation, and dead reconning to figure out a near accurate location to within 50 feet so long as you're in a city. Car navigation systems can do better. They're not even 'pure' GPS services, they have access to mobile cell, they do online updates for maps, and their accelerometers are far better than phones. The software though is simply worse than what Google can provide.
- maxerickson 10y agoPhones do more than use the towers for location information, they use the data connection to download information about the satellite positions, shortcutting a 12.5 minute step: https://en.wikipedia.org/wiki/Assisted_GPS https://en.wikipedia.org/wiki/Assisted_GPS I wonder if the average car system really has the sensors for high quality inertial navigation. If they don't, the navigation won't work very well anyway until it has a decent GPS fix.