A vehicle including a ground speed sensor arranged to detect the speed of travel
of the vehicle on the ground and including a wave transmitter arranged to transmit
waves toward the ground, a wave receiver arranged to received waves reflected from
the ground and a processor coupled to the transmitter and receiver to determine
the speed of travel based on the transmitted waves and received waves. The waves
are transmitted in pulses or modulated such that the processor is able to determine
the distance between a wave-transmission and reception point and the ground (by
time of flight for ultrasonic and electromagnetic waves or phase difference-for
electromagnetic waves) and the velocity of the vehicle (using Doppler analysis).
