Application of Digital Lock-in Amplifier Technique to Field Signature Method

To overcome the problem that the amplitude of excitation direct current (DC) is too large in traditional field signature method (FSM),a method for aspplication of digital lock-in amplifier technique to FSM was proposed.The results showed that digital lock-in amplifier technique could significantly reduce the amplitude of excitation current under the premise of meeting the measurement accuracy in comparison with traditional FSM excitation current,the system could provide efficient and reliable on-line monitoring and evaluation of the inner corrosion of pipelines.