It seems to me that a small percentage error measuring height from the Earth’s centroid of mass will be a much larger error when we are measuring the difference in height of two points each of which has been measured with the error variability described. Also our use of these devices in practice often involves interference with satellite visibility through shielding by the user’s body, or by external objects such as trees, or the material of an enclosing bag or jacket, or the same material when soaking wet, or travelling through gorges, tunnels or buildings. Controlling for these factors is extraordinarily difficult.

I had some off-blog email correspondence which suggested that it may be beneficial to speed up the sampling rate of my device in order to give the algorithm a better chance of working out a decent average value for the height. I’ve done this, and need to gather some data to see if it’s made a difference. I’ll report here when I have more to say.