GPS data - HDOP less than 1.0

The red-orange-yellow data points are the differences in metres from previous sequential lat/long reading.  Deep red is good (0m - 0.15m) to yellow, (0.67m - 0.78m).  Superimposed on top is a display of histogramed GPS HDOP with dark purple (best: 0.76 - 0.80), to light purple (worse: 0.94 - 0.99).

This also shows an outside iPhone test, where I placed it out on the fence top (green diamond) and plotted the resultant reading (lower black diamond) some 3m south of the iPhone.