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There have been a lot of questions raised about the accuracy of the iPhone GPS receiver, the size of the antenna, the update frequency and so on have all been called into question.

So I decided to try a simple test as I am currently learning how to develop iPhone applications that make use of the GPS. Using a 3rd party application to log the GPS co-ordinates from the iPhone, I cycled a 3.5 mile route through a suburb of London and exported the co-ordinates as a KML file and loaded the path into Google Earth. I then manually drew an accurate path in Google Earth of the same route.

As I was cycling, bear in mind that I made use of the pevement in places, as well as the road.

Basically the purple line in the video below is the path I drew manually and is as accurate as you could hope for. The white line is the path as determined by the iPhone GPS unit.

While a consumer GPS system will never place you to within a metre (as my manually drawn path does) I think the iPhone GPS unit is, overall, pretty accurate. Certainly it looks to me as though it would be up to the task of powering proper real time navigation software such as that typically found in car sat-nav units. I would imagine that car sat-nav units clamp the location to the nearest road using some sort of algorithm so slight deviations don’t affect them.

Filed under: Gadgets
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