Fractional tap spacing in digital communication systems

The most favorable sampling rate for receivers with a fixed continuous filter, sampling orientation, and secondary time-discrete system is investigated. The basic model is presented and transverse equalizers are considered as time-discrete filters without time restriction. For different scanning rates and arbitrary sampling instant shifts, optimal equalizers are presented according to the average quadratic error criterion. Transverse equalizers with a finite number of pickups are examined, and a known solution for the optimal equalizer coefficients is applied to the generalization of equation systems. In addition to the derivation in the time domain, an analysis is conducted in the frequency domain which clarifies the effects related to fractional tap spacing. Numerical examples demonstrate a few important characteristics of the receiver, and a table provides an overview of the modes of operation of various classes of communication channels.