Browse Prior Art Database

Binary Linear Write Equalization

IP.com Disclosure Number: IPCOM000047275D
Original Publication Date: 1983-Oct-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 54K

Publishing Venue

IBM

Related People

Davie, NR: AUTHOR [+2]

Abstract

A general method of write equalization is described for magnetic recording. It is applicable to all (d,k) run-length limited codes. It is linear. Therefore, the amount of equalization does not vary with the write data pattern. It uses conventional two-level write current. A block diagram of the system is shown in Fig. 1. In the Fig. 1 system: T=desired Pulse Width; D=delay of T seconds; DN=delay of N x T seconds; MIN=time of shortest wavelength P=MIN . T DEL=required delay to align pulse with input Q=DEL . T The defining parameters are D, P and Q. An exemplary timing diagram is given in Fig. 2 for a (1,k) run-length code. If there is a head power dissipation problem, the write current may be sampled as shown in Fig. 3.

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Binary Linear Write Equalization

A general method of write equalization is described for magnetic recording. It is applicable to all (d,k) run-length limited codes. It is linear. Therefore, the amount of equalization does not vary with the write data pattern. It uses conventional two-level write current. A block diagram of the system is shown in Fig. 1. In the Fig. 1 system:

T=desired Pulse Width; D=delay of T seconds;

DN=delay of N x T seconds;

MIN=time of shortest wavelength

P=MIN . T

DEL=required delay to align pulse with input

Q=DEL . T The defining parameters are D, P and Q. An exemplary timing diagram is given in Fig. 2 for a (1,k) run-length code. If there is a head power dissipation problem, the write current may be sampled as shown in Fig. 3. It is assumed that the flux bubble is at least 2 code bits wide in the example. All previous methods are particular subsets of this general case. The general case comprises a linear method of write equalization of preselected run-length magnetic recording code using two-level write current to produce low-frequency signals of reduced amplitude and high-frequency signals of increased amplitude comprising the steps of deriving an NRZI signal having transitions that indicate the presence of data ones, and adding to the NRZI signal N-d pulses of equal spacing, where N represents the number of zeroes between transitions and d represents the number of zeroes that must exist between transitions for certain preselected run-l...