RT_INS_Vel_NED_1: INS North and East Velocity
RT_INS_Vel_NED_1: 142, 16 (0x8E1020 + unit id) (0x390)
Byte 0: Validity
Byte 1: Accuracy (N & E)
Bytes 2-4: INS velocity N (m/s)
Bytes 5-7: INS velocity E (m/s)
NED velocities are velocities in the local North, East and Down directions at the current location.
Speed resolution is m/s * 1e-4.
Accuracy resolution is m/s * 1e-2.
NED velocity has components in the local North, East and Down directions. E.g. an NED velocity of 2, 2, 0 implies that the vehicle has a velocity component in the North direction of 2m/s and a velocity component in the East direction of 2m/s, and no vertical velocity component (the vehicle is travelling exactly on the flat). In this case, the vehicle is heading NE, and would have a speed of 2.83m/s (square root of 2*2 + 2*2 + 0*0).
Accuracy is an approximation to the 1 sigma standard deviation of the velocity value.