Patent ID: 8111988

Claim:
A method for monitoring a wavelength-division multiplexed signal, comprising: generating a first objective signal including a first objective wavelength λ o1 , generating a second objective signal including a second objective wavelength λ o2 , selecting a guard wavelength λ g according to a channel hopping protocol wherein the guard wavelength λ g varies between λ o1 and λ o2 , and generating a guard signal including the guard wavelength λ g that is between λ o1 and λ o2 ; generating a wavelength-division multiplexed signal by wavelength-division multiplexing the first objective signal, the second objective signal, and the guard signal, wherein the wavelength-division multiplexed signal includes: a first multiplexed objective channel, a second multiplexed objective channel, and a multiplexed mud channel having a range of wavelengths between λ o1 and λ o2 ; receiving the wavelength-division multiplexed signal by a monitor; and determining an error of the multiplexed guard channel by comparing the multiplexed guard channel to the guard signal.