Weak electromagnetic eddy signal is not easy to detect

thus limits its use in the field of rail flaw detection. Based on basic principle of electromagnetic eddy detection

design internal reference orthogonal phase sensitive detector and digital low-pass filter to form digital lock-in amplifier algorithm

simulate and verify this algorithm. Use NI-PXI controller to control signal generation and acquisition card

design electromagnetic flaw detection sensor and peripheral circuit

combine with digital lock-in amplifier algorithm to form rail flaw detection platform

which measure the rail sample with different frequency and detect the rail defects effectively.