Method for controlling the signal/noise ratio of optical add/drop signals
AssigneeSiemens Aktiengesellschaft
InventorsChristian Eder, Claus-Jorg Weiske
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Abstract
A method and apparatus for controlling the signal/noise ratio of optical add/drop signals in an optical WDM transmission system having a transmitter unit, a receiver unit and at least one optical add/drop multiplexer for transmitting optical express signals and at least one optical add/drop signal wherein the power spectrum of the pre-emphasized express signals is determined, and the signal level of the at least one optical add/drop signal is adapted to the power spectrum determined for the express signals.
Claims8
A method for controlling a signal to noise ratio of optical add/drop signals of an optical WDM transmission signal in an optical WDM transmission system having a transmitter unit, a receiver unit and at least one optical add/drop multiplexer for transmitting both optical express signals and at least one optical add/drop signal, the method comprising the steps of:
- determining signal to noise ratios of the express signals in the receiver unit;
- controlling signal levels of the express signals in the transmitter unit as a function of the determined signal to noise ratios of the express signals;
- determining a power spectrum of the express signals;
- adapting a signal level of the at least one optical add/drop signal to the power spectrum determined for the express signals;
- calculating, prior to the step of adapting, an insertion loss for at least one of the express signals;
- measuring a signal level of a drop signal;
- and
- determining a signal level of an add signal, necessary for the step of adapting, from both the calculated insertion loss and the measured signal level of the drop signal, and setting the signal level of the add signal before injection into the WDM transmission signal.
An apparatus for controlling a signal to noise ratio of optical add/drop signals of an optical WDM transmission signal in an optical WDM transmission system, comprising:
- a transmitter unit;
- a receiver unit;
- and at least one optical add/drop multiplexer for transmitting both optical express signals and at least one optical add/drop signal, said add/drop signal having a measured signal level;
- wherein an insertion loss for at least one of the express signals is calculated, for the at least one multiplexer optical add/drop multiplexer, and wherein the signal to noise ratios of the express signals are determined in the receiver unit, and signal levels of the express signals are controlled in the transmitter unit as a function of the determined signal to noise ratios of the express signals, a power spectrum of the express signals is determined, and an add signal level is calculated for adapting to the power spectrum for the express signals, said add signal level being calculated from both the calculated insertion loss and the measured signal level of the drop signal, wherein the signal level of the add signal is set before injection into the WDM transmission signal.
Dependencies are inferred from the claim text.