Browse Prior Art Database

Constrained Channel Coding With Spectral Null

IP.com Disclosure Number: IPCOM000047261D
Original Publication Date: 1983-Oct-01
Included in the Prior Art Database: 2005-Feb-07

Publishing Venue

IBM

Related People

Authors:
Langdon, GG Siegel, PH Todd, S [+details]

Abstract

This invention relates to a method for the definition of a Finite State Machine (FSM) for a constrained channel giving a spectral null at f/n and which has a manageable number of internal states. A second object is to show how a combination of coding techniques from the prior art may be employed, together with an approximation step, to encode and decode channel strings. In the prior art, discrete constrained channels such as for magnetic recording are studied. A channel clock measures channel time units of a given duration, the reciprocal of that duration being clock frequency "f". A spectral null at "f/n" occurs at a frequency whose period is "n" clock times. The signal amplitude is a(i) at clock time i.