This transfer function is given in equation 25.C-7. The baseline wander model includes the receive magnetics and line termination. To eliminate this duplicity, a filter is constructed that compensates for the magnetics in the DUT and allows the baseline wander model to completely define the channel's low frequency response. An equivalent circuit for this configuration is shown in figure 25.C-3. The skin effect describes the tendency of AC currents to ride along the surface of a conductor.
Higher frequencies correspond to a thinner skin and a higher loss.
The transfer function of a pure skin effect loss is given in equation 25.C-9. In equation 25.C-9, l denotes the length of the cable in meters, f is the frequency in Hertz, and k is a constant that will be derived from the standard for category 5 cable. Equation 25.C-10 is valid for frequencies in the range of 0.772 to 100MHz. The pure skin effect model is modified to incorporate the high frequency correction and the baseline wander model is left to define the low frequency response. The transfer function for the modified cable model is given in equation 25.C-11.