C-band DWDM and 18-wavelength CWDM tunable OTDR series for metro Ethernet, remote PHY and passive C-RAN link characterization. This series includes one CWDM tunable OTDR module to cover all 18 CWDM channels from a single port and one DWDM tunable OTDR module to cover DWDM C-Band channels. This solution is available in the FTB-1V2, FTB-2 and FTB-4 platforms. The series is designed to stabilize the central wavelength under test to prevent drift/leakage into adjacent channels and is scalable by adding channels to grow with the network. The user interface lets technicians define favorite channels over the C-Band (DWDM) or CWDM grid for quicker access and more efficient routines.