A receiver applies a calibration method to compensate for skew between input channels. The receiver skew is estimated by observing the coefficients of an adaptive equalizer which adjusts the coefficients based on time-varying properties of the multi-channel input signal. The receiver skew is compensated by programming the phase of the sampling clocks for the different channels. Furthermore, during real-time operation of the receiver, channel diagnostics is performed to automatically estimate differential group delay and/or other channel characteristics based on the equalizer coefficients using a frequency averaging or polarization averaging approach. Framer information can furthermore be utilized to estimate differential group delay that is an integer multiple of the symbol rate. Additionally, a DSP reset may be performed when substantial signal degradation is detected based on the channel diagnostics information.