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Coding for Data Transmission

IP.com Disclosure Number: IPCOM000091418D
Original Publication Date: 1968-Jan-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 59K

Publishing Venue

IBM

Related People

Gorog, E: AUTHOR [+2]

Abstract

Some codes, obtained from the 4-out-of-8 code, reduce the width of the transmission spectrum. It is possible to obtain such a code, called Transmission Adapted Code, from a 4-out-of-8 code by inverting every other bit, either all even or all odd bits. This is not only applicable to two-level 4-out-of-8 codes, but also to multilevel 4-out-of-8 codes, particularly to codes with an even number of levels.

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Coding for Data Transmission

Some codes, obtained from the 4-out-of-8 code, reduce the width of the transmission spectrum. It is possible to obtain such a code, called Transmission Adapted Code, from a 4-out-of-8 code by inverting every other bit, either all even or all odd bits. This is not only applicable to two-level 4-out-of-8 codes, but also to multilevel 4-out-of-8 codes, particularly to codes with an even number of levels.

A two-level TAC code is obtained from the two-level 4-out-of-8 code, by inverting every other element. These two-level data are combined in order to obtain a multilevel code, four levels for example. The result is a multilevel code presenting the characteristics and advantages of the known two-level TAC code.

It is possible to reverse the order of operations, first effecting the passage to multilevels and then carrying out the inversion. The inversion of every other element is identical to that effected in the known case, where the two-level 4-out- of-8 code is transformed into a two-level TAC code. The series of two-level elements obtained is transformed into a series of multilevel elements.

In the circuits, the values corresponding to a character X arrive on inputs
11...18 of register 1. Clock 2 provides Alpha pulses which shift register 1 whose contents are sent to logic adder 4. The latter receives the output from trigger 3 which is also controlled by Alpha pulses. If trigger 3 is set to 1 at the initial instant, output 4' delivers t...