Hi eka-eka,
Thanks for your interest! I'm not quite sure which question you're asking here, so I'll provide some information and you can let us know if you need more detail. WiGLE actually receives measurements - observations from mobile client and various stumbling packages, rather than pre-computed values. Using all the observations, we perform a calculation that weights all the observations according to the square of the signal strength at the point observed, making an educated guess at the AP location by a signal-strength weighted average. This process is probably correctly termed "Signal-strength-weighted centroid trilateration" or "multilateration" - although we referred to it as "triangulation" for years before we actually read enough RF literature to correct our terminology.
If you're looking to perform observation on a PC: you'll need one of the many stumbling/wardriving packages out there (such as Kismet, NetStumbler, Kismac, or any package listed on
the dialog on our upload page. Different wireless chipsets are supported in different ways under different operating systems (so check out support for your hardware when choosing a package), and if you're moving around, you'll also want a GPS.
If you're looking to perform calculations locally, it depends on your data source and level of technical expertise... but you can probably program in your favorite language or structure a trilateration estimator in your favorite formulaic spreadsheet package based on the description above!
Cheers and welcome!
-a