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Bidirectional Read Skew Compensation

IP.com Disclosure Number: IPCOM000096611D
Original Publication Date: 1963-Aug-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Rudy, CJ: AUTHOR

Abstract

The read-skew among parallel recorded bits in different tracks on magnetic tape increases as the density of recorded bits increases. However, when reading tape in a forward direction, the skew among a group of parallel recorded bits is different from that found among the same bits, when they are read in a backward tape direction. The most leading track in the forward direction becomes the most lagging track in the backward direction, and vice versa. As a result, the skew image in the backward direction is the reverse of the skew image in the forward direction.

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Bidirectional Read Skew Compensation

The read-skew among parallel recorded bits in different tracks on magnetic tape increases as the density of recorded bits increases. However, when reading tape in a forward direction, the skew among a group of parallel recorded bits is different from that found among the same bits, when they are read in a backward tape direction. The most leading track in the forward direction becomes the most lagging track in the backward direction, and vice versa. As a result, the skew image in the backward direction is the reverse of the skew image in the forward direction.

Circuits 20A... 20N respectively deskew parallel tracks with tape moving in either a forward or a backward direction. Read head 10 reads the bits in a track and they are amplified by preamplifier 11. Forward gate 12 and backward gate 13 each have inputs receiving the output of preamp 11. However, only one of gates 12 or 13 is activated at any one time according to the direction of tape movement. Thus, a forward signal is provided on line 14 to activate gate 12, when the tape is moved in a forward direction. A backward signal is provided on line 15 to activate gate 13, when the tape is moved in a backward direction.

A delay line 16 has one end connected to the output of gate 12. Its other end is connected to the output of gate 13. The output of delay 16 is taken from one of its taps 15, which obtains proper skew compensation, when the tape is moved in one direction. The t...