Determining speed of rail vehicle relative to fixed ultrasonic signal guide i.e. railway track

摘要

The speed determn. involves a signal guide (4) which forms part of the railway track and is in operative connection with the vehicle (1). In a predetermined transmission position (P1) of the vehicle at least one ultrasonic characterising signal is transmitted to the signal guide (4). In a predetermined reception position (P2) of the vehicle, a given distance s from the transmission position in the drive direction, or in the opposite direction, the characterising signal is detected. The vehicle speed v is calculated according to the equation v=( DELTA f.c-s)/( DELTA tf- DELTA t0) when the transmission position is behind the reception position in the driving direction. When the transmission position is in front of the reception position, the speed v is calculated using the equation v=( DELTA tf.c+s)/( DELTA tf- DELTA t0), where c is the propagation speed of the characterising signal, DELTA tf is the cycle time of the signal when the vehicle is moving, and DELTA t0 is the cycle time of the signal when vehicle is at rest.