In my previous post, I mentioned getting the latitude and longitude choordinates for my house. I tried taking my laptop out with my USB GPS, but it was snowing a little, so I scrubbed that mission. I put the laptop on my desk to let it charge up and forgot about it. I left the GPS and mapping software run figuring I’d need it later.
So just now I notice that the GPS has picked up a signal and was mapping. The GPS has never picked up a signal inside the house before, but it was near a window this time. This was the pattern it picked up:
Note how all the data points run north/south. Almost all of the data points are yellow, which means it could only latch on to the signal of 2 satellites. The line is a few hundred yards from where my house actually is. I don’t know how accurate the map is for this neighborhood.
The interesting thing about the north/south line is that its sort of visual proof of triangulation. With limited data, you can’t tell for sure where you are, only that you are on some line. You need a third source of info to get that line down to a point, and a fourth signal to get your altitude. The more sources you get, the better you can extrapolate your position. This screenshot is unique only because its hard to get data this weak on a regular basis. Usually you either get a strong signal, or none at all.