4th May 2010, 11:03 PM
I have my doubts about handheld GPS, particularly the cheap models. I've seen many cases of GPS points that are wildly out - up to 20m in some cases. I've also seen the trace from a colleague's GPS that was left in a van overnight - it wandered around a 10m radius. And yet I have seen these handheld GPS units being used to survey in site extents and even trench locations! I totally agree with Kevin that a competent surveyor could probably achieve similar or better accuracy using more traditional methods, a possible exception being thick woodland. But surely in any event a cheap handheld unit should never ever be used for anything more than a very broad-brush walkover?