Detector circuits for ternary coded magnetic recording

It has been shown [1] that the recording density ratio and the detection window can both be increased by the use of a ternary, i.e., 3-symbol, rather than binary recording technique. The three symbols, φ, 1 and 2 are represented in the media as absence of flux reversal, single reversal and two closely spaced reversals respectively. The implementation of coder and decoder for such a ternary code has been presented previously[2]. This paper presents a realization of detector circuits to distinguish Singlets (ones) and Doublets (twos) in the readback signal from each other and from noise and to detect the precise time-of-arrival for each of them. It also presents a slightly modified version of the code and points out how this simplifies the detector circuit.