Abstract
In this paper we consider how to realize the radio wave speedometer that uses the spatial pattern of electric field intensity of radio waves propagated from a broadcasting station as the spatial measure. The radio wave speedometer measures the speed relative to the space in which radio waves are standing, whereas the conventional methods like as the Doppler method, the spatial filtering method and the correlation method measure the speed relative to the ground. The prior research verified the validity of the radio wave speedometer under restrictive circumstances such as on the roof of a building.
Here we investigate if the radio wave method can work correctly under real situations and circumstances where many vehicles are running. We developed a two channel electric field intensity meter with the wide dynamic range and quick response. The properties of the electric field pattern i.e., (1) the stability of the pattern, (2) the difference of the pattern when moving to different directions, and (3) the influences by the moving reflectors were investigated by using the meter developed. Further we investigated if the radio wave speedometer can measure the accurate speed of a vehicle in the variety of real roads by experiments.
It was verified that the patterns were stable at most places where we carried out experiments and little influences were observed by the moving reflectors like as automobiles. Thus the patterns can be used as the spatial measure for the speed measurement in real situations. The speed measured by the radio wave speedometer showed the good reproducibility and linearity.
