Filtering of Spatial Low Frequency Components in the Pattern of Radio Wave Intensity and Speed Measurements by a Radio Wave Spatial Filter

Abstract

This paper describes a new type of radio wave spatial filtering to measure the absolute speed of vehicles. The electric field intensity of radio waves generated and propagated from a broadcasting station demonstrate stochastically periodic and non-Gaussian spatial patterns due to the multi-pass fading phenomenon. We detect the patterns and apply the spatial filtering technique to the patterns to measure the absolute speed. Here we investigated the optimal conditions of the filtering via the study on the stochastic property of the patterns. We developed the optimal filtering system. Experiment carried out by the filter on real roads by real automobile demonstrated the validity of the proposed radio wave spatial filtering.