• High Linear Density Recording Study

      Levy, Avner; Bell & Howell (International Foundation for Telemetering, 1978-11)
      A series of tests were conducted in an attempt to study the recording behavior of Enhanced Nonreturn to Zero (ENRZ) code at high linear recording densities. Using the "eye" pattern as a criteria in the first phase, the tests clearly demonstrate the sensitivity of a tape recorder to the DM (Delayed Modulation) coding technique as compared to ENRZ. For the same linear density, ENRZ has a considerably wider margin than the DM code. In the second phase of that study, a series of tests were conducted using high energy tape and magnetic heads with reproduce gaps in the order of 12 μin, referred to as "double bandwidth heads." Using present day technology, it was possible to demonstrate linear packing density never before achieved on magnetic recording tape.
    • Summary of Enhanced NRZ Code Properties

      Fairfield, Anthony G.; Schulze, Glen H.; Bell & Howell (International Foundation for Telemetering, 1978-11)
      A summary of the properties of Enhanced NRZ (ENRZ) for magnetic tape recording is presented. Major code properties are defined and, where informative, compared with competing recording codes. Considerable insight is given into the considerations for maximizing the recording density without abusing the limited bandwidth of the tape recording channel. Several standard configurations with multi-track deskewed formats currently in field use are presented with throughput rates up to 320 MBPS. Error-detection and correction for improving Bit Error Rates of inferior tapes to 10⁻¹⁰ is outlined.