This paper proposes design criteria for the crosstalk interference between digital line systems operating in multipair cable, with plesiochronous and synchronous network configurations. Existing solutions are shown to be appropriate in some cases, in some other cases to be based on imperfect design criteria, and in other cases, such as the plesiochronous case, to be absent. For engineering purposes, the application of a 3 dB additional margin to the design criterion based on the classical solution should be adequate for practical application in the network.

An expression is derived for the mean square error of a SSBAM or a baseband multilevel class 4 partial response data signal when distorted by a channel which has a sinusoidal phase ripple. Such characteristics are approximated when the channel has been equalized by so called "bump" group delay equalizers. Included are the expressions for the optimum carrier phase and sampling time. For a low frequency group delay ripple, it is shown that the error can vary by a factor of seven for differing frequency and phasing of the ripple with the same peak group delay variation.

An expression is derived for the mean-square error of an SSBAM multilevel class 4 partial response data signal when distorted by a channel with parabolic group delay with the minimum value centered in the signal spectrum. The optimum carrier phase and sampling times are also determined. Numerically evaluated results indicate that the approximation errors made in the derivation are not significant in the regions of practical interest.

A general expression is derived for the eye pattern boundaries of a multilevel class-4 partial-response (PR) signal after single-sideband amplitude-modulation (SSBAM) transmission with a carrier phase error. From the expression particular results are obtained for the horizontal and vertical eye openings of the signal. Expressions are derived for the tap settings of a linear transversal equalizer using the minimum mean-square error (MMSE) criterion when the class-4 PR signal is distorted by a carrier phase error and sampled with timing error. The values of the tap settings can be used to reduce the carrier and timing phase errors. Finally, an expression for the vertical eye opening of the equalized signal is derived as a function of the carrier phase and the number of stages in the equalizer.

A general expression is derived for the tap settings of a linear transversal equalizer using the minimum mean-square error (MMSE) criterion when the class-4 partial-response (PR) signal is distorted by noise as well as carrier phase and timing errors. The values of the tap settings are used to reduce the carrier and timing phase errors.

Considering the eye-openings of a Class 4 partial response signal, expressions are derived for the horizontal eye-opening and for the vertical opening after single-sideband (SSB) transmission with a carrier phase error. The latter result is obtained at both the original sampling time and at the optimum sampling time.