Errors which occur randomly by unknown and unpredicatable changes in the measurement environment.
One technique for trying to remove errors from positioning computations is to perform many position computations, and to determine the average over all solutions. Many receivers allow the user to do this. It should, however, be clear from the above that averaging may address random errors such as signal noise, selective availability (SA) and multi-path to some extent, but not systematic sources of error, such as incorrect satellite data, atmospheric delays, and GDOP effects. These systematic sources should be removed before averaging is applied.
It has been shown that averaging over 60 min in absolute, single-point positioning based on code measurements, before systematic error removal, leads to only a 10–20% improvement of accuracy. In such cases, receiver averaging is therefore of limited value and requires near-optimal conditions for long periods. Averaging is a good technique if systematic errors have been accounted for.