A method of monitoring optical parameters of a modulated optical signal comprises receiving a first optical power, Xi, of said optical signal for a first bandwidth, Bi, across the said optical signal and receiving a second optical power, Xj, of said optical signal for a second bandwidth, Bj, across the said optical signal. A peening apparatus is also disclosed. The coded data is converted into a first channel data suitable for the optical recording medium. The communication network also retrieves a subscriber profile associated with the second subscriber.