If the derived accuracy states 1.8m then that means that at that point of time the specified GPS receiver position could be up to 1.8 meters in any direction from the actual indicated point.

Whatever integration time and static settling time that it took to arrive at that 1.8 meter stated accuracy may go invalid the moment the GPS receiver is moved. However if the movement is very slow relative to the sampling rate and the current accuracy spec then the motion is fairly easy to track in real time. So if you are walking the reading probably tracks nice as long as a minimum necessary number of satellites stay in range. On the other hand if your traveling on a rocket sled at 9876 meters per second do not expect the next GPS reading to represent anything valid until the sled either runs out of fuel or crashes. Do not forget to jump just before the crash.

Michael Karas