Abstract: A receiver for a digital data transmission system comprises a sampling device for sampling digital data signals received from a subscriber loop. A precursor equalizer connected to the output of the sampling device equalizes, in effect filters, the sampled digital data signal. A timing recovery circuit connected to the output of the precursor equalizer controls the sampling device in dependence upon the filtered digital data signal. The precursor equalizer has a difference equation such that the equalized digital data signal has at least one zero-crossing occurring substantially one baud before the main cursor of each pulse. For twisted wire pair subscriber loops, the precursor equalizer may have a different equation: ##EQU1## which produces a single precursor zero-crossing. Alternatively, the precursor equalizer may have a difference equation: ##EQU2## which produces two precursor zero crossings, y(n) being the input to the filter, w(n) its output, h.sub.0 the main cursor height before equalization and h.sub.

Abstract: In a receiver for a loop interface of a digital data transmission system, a received four-level substantially randomized digital signal is sampled and a multilevel slicer compares the samples selectively with a plurality of thresholds to extract the symbols. A timing recovery circuit determines the sampling instant as a function of a precursor sample and a main pulse sample one baud apart, according to the timing function:f(t)=(1/r)h(t)-h(t-T)where 1/T is the baud rate, h(t) and h(t-T) denote the main pulse sample and precursor sample, respectively, r is the ratio between the main pulse sample and the precursor pulse sample, and t is the sampling instant. The timing recovery circuit includes: a timing estimator responsive to baud rate samples before and after slicing, respectively, for deriving a precursor estimate (z.sub.

Abstract: In a receiver for a loop interface of a digital data transmission system, a received four-level substantially randomized digital signal is sampled and a multilevel slicer compares the samples selectively with a plurality of thresholds to extract the symbols. A timing recovery circuit determines the sampling instant as a function of a precursor sample and a main pulse sample one baud apart, according to the timing function:f(t)=(1/r)h(t)-h(t-T)where 1/T is the baud rate, h(t) and h(t-T) denote the main pulse sample and precursor sample, respectively, r is the ratio between the main pulse sample and the precursor pulse sample, and t is the sampling instant. The timing recovery circuit includes: a timing estimator responsive to baud rate samples before and after slicing, respectively, for deriving a precursor estimate (z.sub.