Function to compute one GPS feature from a data window.
Usage
computeOneGPSFeat(w, lastCoordinates)
Arguments
w
Data frame of GPS measurements from the PALMS system. Should contain the following fields: identifier, dateTime, speed, distance, duration, ele, elevationDelta, lat, lon, nsatUsed, nsatView, snrUsed, snrView, fixType
lastCoordinates
Coordinates of last data sample, to compute change in position - data frame with fields lat and lon.