In part one
of this article, I described how to write an interpreter for raw GPS NMEA data. The article included source code in VB.NET which harnessed the power of GPS satellites to determine the current location, synchronize the computer clock to atomic time, and point to a satellite on a cloudy day. The interpreter also works with hand-held devices and supports international developers. Yet, the interpreter was really not suitable for commercial use because it did not monitor precision. Without precision, an application could end up making unintelligent business decisions such as accidentally telling a driver to turn left into an alley, or worse. In this second part, I’ll cover precision in detail and talk about what it takes to make GPS applications smart enough for in-car navigation and reliable enough for business use.