Sinusoidal frequency scan OFDR with fast processing algorithm for distributed acoustic sensing

) where N is the number of backscatter samples. In this work a fast processing algorithm for SFS-OFDR, with computational complexity O (N log N), is derived and its performance and limitations are studied in details. The new algorithm facilitated highly sensitive DAS operation over a sensing fiber of 64km, with 6.5m resolution and scan rate of 400Hz. The high sensitivity of the system was demonstrated in a field trial where it successfully detected human footsteps near the end of the fiber with excellent SNR.