In the interrogation system designed for seismic sensing,the parameter control of long period fiber grating（LPFG） during fabrication is discussed,and the LPFG is employed as a linear edge filter because of its high slope efficiency of 0.998 96 from 1 550.35 nm to 1 553.14 nm and power sensitivity of 1.692 dBm/nm.The background noise is eliminated by comparing the reference signal with the filtered signal.LabVIEW is used as processing function module to acquire and analyze data.The sensitivity of...