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verumgero's Avatar
Posts: 221 | Thanked: 43 times | Joined on Oct 2007 @ Sendai, Japan
#9
Originally Posted by Lord Raiden View Post
Ok, I've been doing some research into this, and aside from having a better GPS chip, one of the things that the stand along GPS units, such as the Garmins, have that makes them better than the NIT for GPS locking, and allows them to lock on in only a matter of a few seconds is a rather neat system that I've unofficially called "GPS drift adjustment". Essentially what the GPS's do is, when they do their first time lock, it can take 2-10 minutes or more to get a full lock. After that it's just a few mere seconds.

The way they achieve this is to remember the last known coordinates of the GPS satellites they had locked onto when they're turned off, and then when they are powered on and go for their initial lock again, they take that information, adjust for date/time and figure out what the drift is. Then they apply that information and use it to look for the satellites they need, and surprisingly enough, they're accurate about 99% of the time.

So for example, if GPS satellite 5 was last seen at 12x65 degrees (12 degrees on the compass, and 65 degrees vertical assent) and it drifts 8x12 degrees every hour, then the GPS device simply needs to do is take that information, look at the last known position, the current time, and then calculate where it should be now. By rights it should then find the satellite right where it expects it to be. I think that if we could apply something like this to the GPS on the NIT, either directly, through a secondary app, or via any of the associated GPS apps (Maemo Mapper, Navit, etc) then GPS locks could be done really, really darned quickly. Heck, in a matter of a few seconds from power on just like the big boys do. Whatcha guys think? Anyone wanna try and tackle this?
HA! I knew it! I have a bluetooth GPS module for my n800 and I have noticed that it locks on real fast if I am close to the last place I was and it takes longer when I farther away. Best example would be from this last trip I took, I used GPS to find find a train station I had never been to and it locked on really fast. But, after about 9 hours on a train and a few hundred kilometers later I tried to get a lock and it took about 3 minutes.

I like being right.