An investigation into the scale codec system and the design of A-law PCM-to-scale and scale-to-A-law PCM converters

The type of digital coding which has been internationally approved for telephone interexchange transmission is logarithmically-companded Pulse Code Modulation, known as A-law PCM. Delta and delta-sigma modulation with digitally controlled syllabic companding are preferred in military applications and are increasingly used in the local subscriber networks. At the moment the users of these systems are unable to communicate directly with each other. The prime objective of this study is to design digital converters to translate the codes from a syllabically companded mnd logically encoded delta-sigma modulation system, known as SCALE, to A-law PCM codes and vice versa. [Continues.]