Saved track statistics

[jfheath]

Yes - the raw data is very patchy - that is the nature of satnavs. At any one particular time, they cannot give you an accurate position. Nor at any single moment in time can they give you an accurate speed. They rely on a number of readings in order to calculate an 'average value' to fix a position. The speed is calculated as distance / time over a few positional fixes - which is why when you accelarate, the satnav can take about 5 seconds to catch up with you. They can pretty accurately tell you how fast you have been going, but not how fast you are going. Of course, if you maintain a constant speed, the satnav readout is pretty good.

An average value can be calculated in loads of different ways according to the circumstances. Often when spurious readings are thrown up, an average may involve throwing away a few of the most extreme readings at each end, and doing a calculation on what is left. What you get in the log files is what the Zumo obtained from satellites every second or so. I suspect that the satnav obtains many more values to fix its position than that.

[zhamid]

Thanks all. I was going to send the Zumo XT back, but this thread convinced me to keep it.