RT_SB_INS_Vpt1_Vel_NED_2: INS Virtual Point 1 VELNED 2
RT_INS_Vpt1_Vel_NED_2: 143, 2 (0x8F0220 + unit id) (0x3C2)
Bytes 0-2: Virtual point 1 Down velocity (Vel D)
Bytes 4-5: Virtual point 1 Heading
Bytes 6-7: Virtual point 1 Slip
Velocity resolution is m/s * 1e-4.
Heading resolution is degrees / 100.
Slip resolution is degrees / 100.
NED velocities are velocities in the local North, East and Down directions at the current location. 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).
Heading is the direction in which the vehicle is travelling (course over ground), and is undefined when the vehicle is stationary.
Slip is the difference between yaw (the direction the vehicle is pointing) and heading.