Crosstalk in digital transmission over subscriber cable

An analysis of near end crosstalk in digital transmission over a subscriber loop is presented. An analytical expression for NEXT between parallel and between twisted lines is evaluated. The expression depends on physical characteristics of the line. Because the phase characteristic is also known, it is possible to obtain the transfer function of NEXT in the time domain. The amplitude of NEXT increases almost linearly with frequency, not with a power of 3/4 of the frequency as expected from previous results. It is noted that expressions for NEXT, if needed, can be derived using the same method.