Abstract: A system and method are provided for calibrating orthogonal polarity in a multichannel optical transport network (OTN) receiver. The method accepts a composite signal and separates the polarization of the signal into a pair of 2n-phase shift keying (2n-PSK) modulated input signals via Ix and Qx optical signal paths, where n?1. Likewise, a pair of 2p-PSK modulated input signals are accepted via Iy and Qy optical signal paths where p?1. Polarization-adjusted I?x, Q?x, I?y, and Q?y signals are generated. An average magnitude is compared to either 2×the absolute magnitude of (I?x and Q?x), or 2×the absolute magnitude of (I?y and Q?y). The average magnitude value can be used that is either 2×(a predetermined peak signal amplitude), or the sum of the absolute magnitudes of (I?x and Q?x) and (I?y and Q?y). The polarization-adjusted I?x, Q?x, I?y, and Q?y signals are modified until the magnitude comparison is about zero.

Abstract: A system and method are provided for five-level non-causal channel equalization in a communications system. The method comprises: receiving a non-return to zero (NRZ) data stream input; establishing a five-level threshold; comparing the first bit estimate to a second bit value received prior to the first bit; comparing the first bit estimate to a third bit value received subsequent to the first bit; and, in response to the comparisons, determining the value of the first bit. Establishing a five-level threshold includes: establishing thresholds to distinguish a first bit value when the second and third bit values are a “1” value, when the second bit value is a “1” and the third bit value is a “0”, when the second bit value is a “0” and the third bit value is a “1”, when the second and third bit values are a “0” value, and an approximate midway threshold.

Abstract: A system and method are provided for non-casual channel equalization in a communications system. The method comprises: establishing a first threshold (V1) to distinguish a high probability “1” first bit estimate; establishing a second threshold (V0) to distinguish a high probability “0” first bit estimate; establishing a third threshold (Vopt) to distinguish first bit estimates between the first and second thresholds; receiving a non-return to zero (NRZ) data stream; comparing the first bit estimate in the data stream to a second bit value received prior to the first bit; comparing the first bit estimate to a third bit value received subsequent to the first bit; in response to the comparisons, determining the value of the first bit.