I put my hands again in a N810 again. This time I decided to give it a try as an onboard device, and installed the base on my car. The drill holes went in the plastic cap that is discarded when you install a CD-player (yes, I *still* did not install a CD player in car!), so no regrettable scars lefts when I'll eventually return the tablet.
I didn't put much faith in preinstalled Map and in N810 GPS capabilities, but I must admit I was wrong. It takes some time to first lock the GPS position (some minutes), but after it locks, it is very precise, and the Brazil map contains the street maps for Joinville. The errors don't go beyond putting the crosshair in the wrong side of the street (which is most probably map offsets than GPS errors). And it works very well without an external GPS antenna. It even keeps locked indoors, in single-store houses.
Outside Joinville, or being more specific, the very moment you put your feet outside Joinville perimeter, the crosshair gets more and more distant from the hightway -- 2 to 3 km errors. I was still wondering if it could be the GPS, but when I crossed a railway, the crosshair was dead right on spot. The problem was the map. In fact, the highways in my area were plotted the same way as they were in Flight Simulator 2000, so I think both drank from the same fountain. (Google Maps does it right, so there are more recent and more precise Brazil maps).
I went to the seashore to tally the GPS alleged altitude with sea water level. Altitude has a constant +3m offset (showed 3,10m at seawater level), no big deal and seemed to be a constant offset everywhere, so it is easy to compensate for. (I did not find a way to "calibrate" it, though).
A new software has been added to Maemo repository: an experimental A-GPS support. It allows to detect your approximate position by using an Internet connection, just as cell phones do automatically with packet data. Even a gross estimative of current position helps GPS a lot, allowing it to lock in a matter of seconds instead of minutes. But Maemo version goes beyond: it also allows *you* to point your approximate location in a world map, so you don't even need an Internet connection to enjoy A-GPS benefits! This is important in remote areas with no cell phone coverage and mountains that hide parts of the sky.
In short, N810 makes a good GPS and since the price is not that distant from a standalone GPS unit with equivalent screen size, it may be a better option. Hope the GPS keeps this performance in Maemo 5 device, which is the one I'll buy!
