US Patent 10377397 Detection of anomalies in rail wheelsets

This application relates to methods and apparatus for the detection of anomalies in the wheelsets of rail vehicles, for instance for detection of defects such as wheel flats (303) of a wheel (301). The method using a distributed acoustic sensor (106) having a sensing optical fiber (104) deployed along at least part of a rail track (201) as a train (202) moves along that part of the track. The distributed acoustic sensor detects acoustic signals from a plurality of longitudinal sensing portions of the sensing optical fiber. A processor 108 analyzes the acoustic signals to determine the train speed v. Having determined the train speed the processor also analyzes the acoustic signals for a characteristic acoustic signal so as to detect an anomaly in a wheelset where the characteristic acoustic signal is based on the determined train speed. In particular the method may involve at least a first section of track where the train travels with a first speed v1 and a second section of track where the train travels with a second different speed v2 the characteristic acoustic signal may be a repetitive signal at a frequency that varies proportional to the train speed.