| 摘要 |
<p>A Digital Data Storage (DDS) data storage mechanism for reading DDS tapes containing data at either 61 kbpi or 122 kbpi has two circuits for recovering data from signals induced in a magnetic head by magnetic patterns on the tape. One circuit (90) incorporates a clipping amplifier (92), a phase-locked loop (PLL) (94), and a latch (96) to sample the two-level signal obtained at 61 kbpi, at times defined by clock pulses from the PLL. The second circuit (100) incorporates a PR-1 partial-response maximum-likelihood (PRML) detector (110) to decode the three-level signal obtained at 122 kbpi. The cosine frequency response characteristic of the PR-1 channel facilitates use of the same rotary head drum and magnetic head gap for reading tapes at either bit density.</p> |
