Device for measuring the speed of a rail-mounted vehicle

A device for speed measurement in a rail-mounted vehicle comprising:

• at least two sensors (G1, G2) which are arranged on the vehicle at a known distance (L) from each other in the longitudinal direction (Y) of the vehicle, each sensor including:
• field-generating means for generating a magnetization alternating field, surrounding the rail, and comprising a magnetization coil supplied with alternating current, and
• at least one sensor coil separated from the magnetization coil, for sensing field variations which are caused by the movement of the vehicle and being arranged with its sensing direction (Y) substantially perpendicular to the direction of the magnetization field, and
• members arranged on the vehicle and adapted to be supplied with the output signals (u.sub.i1, u.sub.i2) of the sensor coils, to form for each sensor a signal pattern (S1, S2) which corresponds to a time variation of the sensed field caused by the movement of the vehicle along the rail,
• to thereby determine, by correlation of the two signal patterns, the time displacement (t.sub.m) between them, and to determine, on the basis of said time displacement and on the basis of the known distance between the measuring locations, the speed (v) of the vehicle.