ALGORITHMS FOR THRESHOLD LEVEL SELECTION AND DECODER LOGIC DESIGN IN DECISION-AIDED SYMBOL-BY-SYMBOL DATA RECEIVERS FOR MAGNETIC RECORDING APPLICATIONS

Symbol-by-symbol receivers comprise an important class of data receive rs in digital magnetic recording applications. In systems where inters ymbol interference (ISI) is high, these systems often use decision-aid ed decoding methods, A typical system employs threshold level detectio n followed by decoding logic. This paper presents an algorithm for sel ecting decoder threshold level settings and for generating the truth t able for the decoding logic. By making use of all information availabl e to the receiver, it is demonstrated that considerable reduction in t he number of threshold levels required can be achieved in systems wher e the data encoding obeys run length limit constraints, It is also sho wn that selection of decode timing reference may have considerable inf luence on the number of threshold levels required, Application of the algorithm is demonstrated for several partial response signaling chann els. A brief discussion is given on the similarities between the struc ture proposed by this paper and standard decision feedback equalizers.