This thesis investigates the quadratic phase coupling ( QPC) of locomotive signal and the mechanisms giving rise to quadratic phase coupling. Then puts the focus on the relationship between locomotive faults and QPC. 本文研究了机车信号的二次相位耦合特征,分析了产生二次相位耦合的机制,着重讨论了二次相位耦合与机车故障的关系。