ANALOG-TO-DIGITAL CONVERSION The Pulse Code Modulation (PCM) Technique By Dr. Ernest Simo 4.0 Speech Compression Source Coding In speech signals, there is a great deal of Redundency. In digitized speech there is also a great deal of correlation among samples. In other words, the value of the current value is influenced by the value of the previous sample. In cellular and Personal Communication Services (PCS), it is important to optimize the network and user's power and bandwidth resources. This is essentially achieved by minimizing the transmission rate. Source Coding "squeezes out" the redundency and takes advantage of correlation and voice activity in speech, to reduce the required transmission bit rate. This process is referred to as "Compression". CODE: AN INTRODUCTION By Dr. Ernest Simo © 1999 DR. ERNEST SIMO - SPACE2000