A Sampling Window Test Method for Evaluation of Phase Encoded Recorder Systems

Abstract

Self-clocking, digital phase encoded data formats have gained popular acceptance in the field of high density digital magnetic recording. At high transition densities, random noise processes can play a prominent role in determining system performance and reliability. The eye pattern technique of assessing the relative merit of a signal with respect to noise is severely limited at high transition densities. The stringent requirements associated with high density recording and the limitations of eye pattern analysis have stimulated the development of a digitally implemented sampling window analyzer which permits the direct evaluation of the statistical properties of a digital phase encoded reproduce waveform. The analyzer observes data transitions through two time sampling windows for the purpose of estimating pattern independent conditional probability. The statistical parameters of the conditional probability obtained can be used to detect latent sources of noise and to define optimum record zone parameters.