Performance of dropout correction on real magnetic tape waveforms with dropouts

Abstract

The need to increase both linear and track densities in tape recording technology calls for more robustness against dropouts, the sporadic losses in signal amplitude, that are a principal source of errors in tape systems. A dropout correction scheme previously introduced by the authors enables more robust bit detection by restoring the signal afflicted by the dropout event. In this paper, we present the results of using this scheme on real oversampled waveforms from an experimental tape test stand. Real-time implementation using a peak detector has been simulated in this work. Albeit at a low density (1.85 channel bits per PW50), the emphasis of this study is to identify the types of error events caused by dropouts and to demonstrate the feasibility of dropout compensation even in the case of very challenging dropouts presented by the experimental data set. It is shown that this scheme can significantly reduce the frequency of dropout induced cycle slip error events that can be as long as the data block. In other cases, where cycle slip errors do not occur, the number of errors associated with dropout events is reduced, on average, by a factor of more than 2. The sensitivity of the method to the envelope detection method is examined, and this is identified as an opportunity for significantly improving the performance of the scheme.