Slope Overload Noise in Differential Pulse Code Modulation Systems

This paper is concerned with the slope overload noise in Differential Pulse Code Modulation (DPCM) systems, often referred to as predictive quantizing systems. Delta Modulation (AM), the simplest member of the D P C M family, is a European invention of the mid-forties. 1 D P C M was first revealed in a Phillips Company patent 2 in 1951 and as a predictive quantizing system in a patent by C. C. Cutler 3 of the Bell Telephone Laboratories in 1952. AM and D P C M are receiving renewed attention due to the present trend toward digital communications and general efforts aimed at redundancy reduction 4 in picture transmission. The present work was motivated, to a large extent, by the application of D P C M to Picturephone® signal transmission. Work on AM and D P C M was reported in the early and mid-fifties. Most representative are the papers by (i) DeJager 5 on AM, mainly of introductory and descriptive nature, (u) Van de Weg° on uniform DPCM--we will refer to it in the sequel, and (in) Zetterberg 7 whose long paper on AM is the most detailed study of the subject to date. Recent publications note the beginning of a "renaissance" period for AM and DPCM. 8 , 0 , 1 0 , 4 In D P C M systems the quantization noise manifests itself in two forms, the granular noise and the slope overload noise. The granular noise is essentially uncorrelated with the input signal and has a more or less flat power spectrum and an approximately uniform amplitude probability distribution, resembling the granular noise in standard PCM.