Differentiation of power and channel count changes in optically amplified links

1. A method comprising:

measuring a first parameter from a first signal received at a node, wherein the first signal is an optical signal comprising a plurality of wavelengths;

measuring a second parameter from a second signal received at the node, wherein the second signal is an optical service channel;

comparing the first parameter to a third parameter and the second parameter to a fourth parameter; and

setting an optical amplifier configuration at the node based on the comparisons, wherein the optical amplifier is configured to provide constant channel power in the first signal if the comparison of the first parameter and the third parameter indicates a change in the first signal input power level and the comparison of the second parameter and the fourth parameter indicates an opposite change in direction in the second signal input power level.

2. The method of claim 1 , wherein the optical amplifier is configured to provide constant channel power in the first signal if the comparison of the first parameter and the third parameter indicates a change in the first signal input power level and if the comparison of the second parameter and the fourth parameter indicates substantially no change in the second signal input power level.

3. The method of claim 1 , wherein the optical amplifier is configured to provide a previously established constant power output of the first signal if the comparison of the first parameter and the third parameter indicates a change in the first signal input power level and the comparison of the second parameter and the fourth parameter indicates a change in the second signal input power level.

4. The method of claim 1 , wherein the optical amplifier configuration is maintained if the comparison of the first parameter and the third parameter indicates no change in the first signal input power level.

5. The method of claim 1 , further comprising:

identifying a type of system perturbation based on the comparisons of the first and third parameter relative to the second and fourth parameter.

6. The method of claim 5 , wherein the first parameter is a power measurement for the first signal, wherein the third parameter is a baseline power measurement (Pb sig ) of the first signal, wherein the second parameter is a power measurement for the second signal, and wherein the fourth parameter is a baseline power measurement (Pb OSC ) of the second signal.

7. The method of claim 6 , wherein a wavelength count change is identified if the comparison of the first signal power level to Pb sig indicates a change in the first signal power level and the comparison of the second signal power level to Pb OSC indicates substantially no change in the second signal power level.

8. The method of claim 6 , wherein a wavelength count change is identified if the comparison of the first signal power level to Pb sig indicates a change in the first signal power level and the comparison of the second signal power level to Pb OSC indicates a change in the second signal power level which is opposite to the change in the first signal power level.

9. The method of claim 5 , further comprising:

establishing a new output, power for the optical amplifier in response to a channel count change being identified as the type of system perturbation; and

operating the optical amplifier in the node to achieve a constant output power per channel in the first signal.

10. The method of claim 5 , wherein a passive loss is identified as the type of system perturbation if the comparison of the first parameter to the third parameter indicates a change in the first signal power level and the comparison of the second parameter to the fourth parameter indicates a similar change in direction in the second signal power level.

11. The method of claim 10 , further comprising:

operating the optical amplifier in the node to maintain a previously established constant output power, in response to the change of the first parameter and the change of the third parameter being substantially the same power level.

12. The method of claim 1 , further comprising:

establishing a threshold for determining a change in at least one of the comparisons the first and third parameter or the second and fourth parameter.

13. The method of claim 12 , wherein the threshold is on the order of 0.5 to 1 dB.

14. The method according to claim 1 , wherein the measuring of the second parameter comprises directly measuring a power level of the optical service channel using a photo receiver.

15. A method for controlling the operation an optical amplifier, comprising:

measuring a first power value from an optical signal comprising a plurality of wavelengths;

measuring a second power value of an optical service channel;

comparing how the first and second power values change with respect to pre-established references; and

setting an optical amplifier configuration based on the comparison.

16. The method according to claim 15 , further comprising:

detecting a state wherein the first power value and the second power value change in a dissimilar direction, wherein the detection indicates a channel count change; and

establishing a new power output by using a gain prior to the channel count change and the current optical input power.

17. The method according claim 16 , further comprising:

establishing a new power output based on a ratio of the first power value prior to the channel count change, and the first power currently detected to maintain a constant power output per channel/wavelength.