ANALOG-TO-DIGITAL CONVERSION The Pulse Code Modulation (PCM) Technique By Dr. Ernest Simo 2.0 Uniform and Non-Uniform Quantization The Quantization Process Uniform Quantizers are optimal when the input distribution is uniform. They are simpler and much cheaper than Non-Uniform Quantizers. However, Non-Uniform Quantizers are difficult to make and expensive. So, an alternative strategy is to first pass the speech signal through a nonlinearity before using a simple Linear or Uniform Quantizer. The nonlinearity causes the signal amplitude to be compressed. At the receiver, the signal is expanded by an inverse to the nonlinearity. The process of compressing at the transmitter and expanding at the receiver is called "Companding" (Compression-Expansion). CODE: AN INTRODUCTION By Dr. Ernest Simo © 1999 DR. ERNEST SIMO - SPACE2000