# Are the IMU velocities equivalent to the GPS ground velocity, except for the coordinate reference system?

If the velocities measured by the IMU in the body-fixed reference frame are converted into earth fixed frame, are they equivalent to the ground velocity measured using the GPS?

• You question is a good one but its writing makes it hard to follow. You should edit it to highlight why you think it may or may not be the same speed and what distrubs you enough to post this question. That way, the answer will be more specific and complete. – Manu H Nov 21 '16 at 9:24

The components of the velocity vector are usually given in a local-level, local-north reference frame; for example, the north- east, and down components: $v_N$, $v_E$, $v_D$. The ground speed is $v_H=\sqrt{v^2_N+v^2_E}$.