中文摘要：

针对因车体振动而带来的测速与定位误差问题,设计一项基于一阶差分结构的大间隙变面积式传感器。传感器由检测线圈、激励电路、放大电路、线圈检测电路、同步解调电路、差分比较电路和AD采样电路等几部分组成,激励电路产生方波激磁信号,经放大电路放大后,送入检测线圈和解调器。通过对检测线圈和信号检测电路的合理设计,配合后续处理电路,可以快速、准确、可靠地完成测速定位功能,并进行了实验验证。实验结果表明：传感器可以准确地检测到轨枕的位置,测量距离可达5 cm,并且不受车体振动的影响。

英文摘要：

Aiming at the speed measuring and location error problems caused by vehicle vibration,a new large gap and area-variable eddy current sensor which uses first difference is designed.The sensor is composed of test coils,excitation circuit,power amplifier circuit,signal detection circuit,demodulation circuit,differential comparison circuit and sampling circuit.The excited signals produced by excitation circuit are amplified,then provided for the test coils and the demodulator.By the appropriate design of the test coils,the signal detection circuit,and the posterior processing circuit,the function of speed detection and relative location can be achieved quickly,exactly and reliability.The availability of the new sensor is verified by ground simulated experiment.The test results show that the new sensor can detect the position of the sleeper accurately,a 5 cm detecting distance is achieved and the measurement results will not be influenced by vehicle vibration.