Detecting Horizontal Movement

[JetPack Spartan]

When the accelerometer detects acceleration you can determine the speed by the amount of acceleration and the amount of time spent accelerating. Then, if there is no further acceleration or deceleration, you know that you are still moving at that speed. So you won't get feedback that you are in motion, the lack of feedback tells you that your speed hasn't changed.

[amgen]

an accelerometer has a base setting which is derived from "freefall, a no acceleration , no forces base point", so on earth, which is rotating, the reading is an offset from the base point and motion is an offset from that ofset ???