Warning system for detection of ice on road surface - has microwave transmitter directed onto road surface to detect change in dielectric constant between wet and icy conditions

摘要

A warning system for road vehicles indicates the presence of an ice film on the road surface. A light source is directed onto the road surface and the reflections are collected by an on board detector. A microwave transmitter is used as the emitter since dirt and contamination has little effect upon the quality of the received signal. The sensor system responds to a change in the dielectric constant of the road surface between wet and ley conditions. Typically, the dielectric constant for water is 80 and for ice is 2. The transmitter and receiver units are set at an angle to the vehicle.