AFL has been awarded a patent for "Optical Time Domain Reflectometer," US Patent 8,411,259. The patent covers OTDRs where multiple wavelength-specific test signal generators and detector channels are combined on a single OTDR test port. The approach is designed to determine if a fiber is live or dark, to measure the power level of any signals present on the fiber, and to apply test signals (including non-interfering signals) on dark and live fibers without the need for swapping test ports or test equipment.