Coded partial response signalling with peak detection

A form of coding which enables the combination of partial response equalization and peak detection is described. The equalization involves equalizing the magnetic recording channel to an extended class-IV partial response (EPR4) channel. The scheme increases the code rate at the expense of having to discriminate between two different types of peaks. The two types of peaks have different amplitudes and different phases. Decoding is accomplished with a straightforward modification of a standard analog peak detector. The constraint graph for one particular code constraint is given, and it is shown that a rate 5/6 code satisfying the given constraint is feasible. An example waveform is shown from a helical-scan tape machine operating at a channel bit density of 100000 bits/in