DWDM Tunable SM OTDR module (FTBx-740C-DWC). C-band DWDM tunable OTDR for ITU channels 12-62 (1528-1568 nm) supporting 100/50 GHz grids. Part of the FTBx-740C xWDM OTDR Series for metro Ethernet, remote PHY and passive C-RAN link characterization; supports single-ended testing through MUX/DEMUX/OADM and in-service testing with SFP-safe troubleshooting.