| 摘要 |
<p>PROBLEM TO BE SOLVED: To always measure a speed with high accuracy by preventing the phenomenon, where the incident angle of a transmission wave for measuring Doppler shift and the reflection angle of a reflected wave is changed to exert effect on a measured Doppler shift value and the speed value operated therefrom. SOLUTION: In a speedometer for having a road surface (5) irradiated with a transmission wave (4) which is an ultrasonic wave or a radio wave and detecting the frequency deviation due to the Doppler effect of the reflected wave (6) from the road surface to measure the ground speed V, the transmission wave (4) from a transmitter (3) is reflected by a offset parabolic reflector (10) to be applied to the road surface (5), and the reflected wave (6) from the road surface is reflected by a separate offset parabolic reflector (12) to be received by a receiver (7).</p> |
