8.1 INTRODUCTION

Correlative coding, or partial-response signaling (PRS) was introduced by Lender [Lender, 8.1] in the 1960s as a technique for data communication. The signaling method differs from the conventional pulse amplitude modulation (PAM) system in that a controlled amount of intersymbol interference (ISI) is introduced to attain certain beneficial effects, such as convenient spectral shapes. Such PRS systems also possess, in general, the property of being relatively insensitive to channel imperfections and to variations in transmission rate [Lucky, 8.2].

Kretzmer [Kretzmer, 8.3] categorized the characteristics of many PRS schemes and compared them on the basis of several performance measures. A unified view of PRS systems is presented in [Kabal, 8.4]. (See [Kabal, 8.4] for a list of many important theoretical and applications-oriented papers in the area, spanning the period 1960 1975.) At present, the importance of this signaling scheme is so well recognized that many textbooks on communication systems, such as [Schwartz, 8.5; Stremler, 8.6; Haykin, 8.7; Lathi, 8.8], cover PRS in detail. It is assumed that the reader is familiar with some of the material in these references or surveys such as [Pasupathy, 8.9; Lender, 8.10]. The purpose of this chapter is twofold; the first is to present a brief tutorial introduction to PRS and the second is to discuss in detail the structures and performances of various PRS decoders and applications reported in the literature. The emphasis throughout the chapter will be...