How accurate is mobile phone GPS?
The first order answer is: probably as good as any other handheld – the physics is the same, regardless of the chipset used, so accuracy to single-digit meters is possible. But in practice, the accuracy is more often going to be limited by the strength of the signal received by the relatively smaller and weaker antenna in a multi-purpose phone than it will be in a single-purpose GPS receiver. Second order, an unaugmented mobile phone probably doesn’t receive and interpret WAAS, EGNOS, or MSAS signals, that are essentially error-correcting signals, rebroadcast via another satellite (NMEA #35, #46, #47, #48, or #51), that indicate an offset to apply to the conventionally calculated position to compensate for ionospheric signal time-of-flight distortion. (The offset is determined by a series of ground stations of known position that also calculate their GPS location, and measure the difference.) Others have speculated that the differential offset signal could be delivered via Internet ins
It all depends on the external conditions, how capable your handset is, and how advanced your network is. Phones aren’t able to do GPS accurately on their own, they get the network to push them assistance information so they can narrow down their search to a certain area. As Mihnea said, the exterior conditions are a big factor as well. Any obstacles in the sky or tall buildings will make GPS reception very tricky. There are ways however to make GPS positioning on mobiles quite accurate. Some networks are using a form of RF fingerprinting. Each time a subscriber makes a GPS positioning, they calculate the signal strengh received by each cell tower and associate that to the GPS position. As they collect data, they are able to map out signal stenghts over the environment. This is very useful in an urban environment, where GPS doesn’t work so great on its own, because every time somebody makes a positioning you know a little bit more about the properties of the area around him/her. The mo
