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Digital Signal Readback Apparatus

IP.com Disclosure Number: IPCOM000082409D
Original Publication Date: 1974-Dec-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Aziz, RA: AUTHOR

Abstract

Sensing or readback of signals stored in tightly packed or abutting tracks is enhanced by using multiread gaps per track. Signals from all of the gaps for each given track are suitably analyzed, with the most reliable signal being selected as the readback signal.

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Digital Signal Readback Apparatus

Sensing or readback of signals stored in tightly packed or abutting tracks is enhanced by using multiread gaps per track. Signals from all of the gaps for each given track are suitably analyzed, with the most reliable signal being selected as the readback signal.

Shown are four tracks, TR1 through TR4, which are recorded by a write gap W having a width substantially greater than the width of any of readback gaps A, B, or C. Readback gaps are preferably equal to about one-half the width of gap W and are displaced as shown; gaps A and B cover one-half of write gap W width, while gap C is centered on gap W. A signal selector analyzes the signals from all three gaps, A, B, and C, selects the best signal and supplies it as the readback signal to the read circuits.

An example of readback signal selection is shown for a two-track system using gaps A and B. Both gaps have identical channels having suitable application signal detection with pointers to error correction circuits (ECC). Readback processing circuits (read) are also duplicated in the two channels. Output signals from the detector and the two read signals are analyzing the quality of the readback for phase, amplitude, conformance to predetermined signal characteristics, such as run length of 1's and so forth (wavelength), are supplied to best circuit selector. For each bit or group of bits, best circuit selection actuates the illustrated switch to select one out of two channel...