EN 61280-2-9:2002 Fibre optic communication subsystem test produres Part 2-9: Digital systems - Optical signal-to-noise ratio measurement for dense wavelength-division multiplexed systems
2009EN 61280-2-9:2009 Fibre optic communication subsystem test procedures - Part 2-9: Digital systems - Optical signal-to-noise ratio measurement for dense wavelength-division multiplexed systems
2002EN 61280-2-9:2002 Fibre optic communication subsystem test produres Part 2-9: Digital systems - Optical signal-to-noise ratio measurement for dense wavelength-division multiplexed systems