Radar and Doppler measurement of speed and distance travelled - using reflective material along stretch of rail to avoid gaps in signal pick up from rail vehicle

摘要

In order to measure the speed or distance the tracked vehicle has travelled, a marker is arranged at the beginning of the stretch which is registered by the vehicle. From this marker, up to the destination, and along the entire length of the track which is radiated by the antenna on the vehicle, and from which the preponderant share of the reflected Doppler signal comes, a material is laid which gives rise to a symmetrical reflection of the radar system signal transmitted from the vehicle. In this way, deviations caused by unevenness of the surface are avoided, guaranteeing an exact measurement of distance due to there being no gaps in the reflected signal. This method also enables very low vehicle speeds to be measure accurately.