Digital audio magnetic recording: Progress in packing density and key technology

In the past twenty years the digital audio tape recorder (DAT) has achieved an extremely high packing density. The present rotary-head cassette tape recorders (R-DAT) achieve a packing density of 114MBPI². The key technologies are (1) high output metal tapes, (2) guardbandless azimuth recording using a suitable 8/10 modulation code, (3) precision tracking by ATF, and (4) a powerful doubly-encoded Reed-Solomon code. Stationary-head tape recorders (S-DAT) employ a multi-track thin-film head which incorporates ICs and a digital time division multiplex signal-processing method, and achieve a packing density of 20MBPI². The R-DAT will replace compact cassette recorders and S-DAT technology will be introduced in multi-track recorders.