Channel monitoring and identification and performance monitoring in a flexible high speed signal processor engine
View Patent ↗Systems and methods are disclosed to provide channel monitoring and/or performance monitoring for a communication channel. For example, in accordance with an embodiment of the present invention, an equalizer is disclosed that equalizes for channel distortions and also provides channel and performance monitoring information, such as for example bandwidth estimation, channel identification, signal-to-noise ratio, chromatic dispersion, and/or polarization-mode dispersion.
1. A method for providing correlation values for determining a power spectral density for a communication channel using an equalizer, the method comprising:
switching off a slicer of the equalizer;
setting tap coefficients of a feedforward filter of the equalizer to fixed values; and
calculating said correlation coefficient values.
2. The method of claim 1 , wherein the correlation coefficient values are calculated based on the following equation, {tilde over (c)} i ≈E(p(t)·p(t−i−τ′)), 0≦i≦N,
where N is the number of tap coefficients, E is the expected value operator, and p is an input signal received by the feedforward filter having eight multipliers.
3. The method of claim 1 , further comprising:
changing one or more of the values for the tap coefficients; and
calculating a set of correlation coefficient values.
4. The method of claim 2 , further comprising calculating the power spectral density based on the set of correlation coefficient values.
5. The method of claim 4 , wherein the power spectral density calculation utilizes a windowing function.
6. The method of claim 1 , wherein the set of correlation coefficient values are calculated based on the following equation,
{tilde over (c)} i,j ≈E(p(t−j·τ)·p(t−i′·τ′)), 0≦i≦N, 0≦j≦N, where N is the number of tap coefficients.
7. The method of claim 1 , further comprising changing timing control ratios of the equalizer to calculate further sets of correlation coefficient values.