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High Rate (0,4) CODE for Peak-Detect Channel

IP.com Disclosure Number: IPCOM000034298D
Original Publication Date: 1989-Jan-01
Included in the Prior Art Database: 2005-Jan-27
Document File: 2 page(s) / 57K

Publishing Venue

IBM

Related People

Patel, AM: AUTHOR

Abstract

A 16/17 rate (0,4) code that has design constraints suitable for the peak-detect channel in magnetic tape products is described. This code maps goups of 16 data bits into 17-bit code words and provides an effective increase in recording density. Code parameters m/n (d,k) represent the code rate and constraints on the run length of zeros in a coded binary sequence. The code rate is m/n where groups of m data bits are mapped into n-bit code words (n>m). Parameters d and k represent the minimum and maximum run length of zeros appearing anywhere in the coded sequence. Run length parameters are (0,4); but this has no significant effect on the self- clocking property, since there are more than adequate clocking transitions in the code.

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High Rate (0,4) CODE for Peak-Detect Channel

A 16/17 rate (0,4) code that has design constraints suitable for the peak-detect channel in magnetic tape products is described. This code maps goups of 16 data bits into 17-bit code words and provides an effective increase in recording density. Code parameters m/n (d,k) represent the code rate and constraints on the run length of zeros in a coded binary sequence. The code rate is m/n where groups of m data bits are mapped into n-bit code words (n>m). Parameters d and k represent the minimum and maximum run length of zeros appearing anywhere in the coded sequence. Run length parameters are (0,4); but this has no significant effect on the self- clocking property, since there are more than adequate clocking transitions in the code. The rate of 16/17 in this code requires mapping of a large number of code words: 65536 code words as compared to 256 for rate 8/9 codes. The assignment of these 65536 code words is carried out using gated partitions, each built upon a specific structure. Implementation of the resultant code is realized with very simple encoding and decoding functions in the form of binary logic equations. MAPPING WITH (0,4) CONSTRAINTS To this create code structure, we introduce symmetry in notation for a data word and a corresponding code word. The data word consists of two bytes A and B where B is denoted backward as: DATA WORD = (A1, A2, ... A7, A8), (B8, B7, ... B2, B1) Similarly, the code word consists of...