ANALOG-TO-DIGITAL CONVERSION The Pulse Code Modulation (PCM) Technique By Dr. Ernest Simo 3.0 Encoding Samples into Bits Encoding Speech Signals From standard landline telephony applications, highest practical frequency components of speech are considered to be around 4 KHz. Applying Nyquist Rule, we shall, therefore, sample our speech waveform at the rate of 8000 samples per second. In order to achieve excellent results on the subjective Mean Opinion Scoring (MOS) tests, 256 quantization levels are required. Each sample is thus represented by 8 bits, yielding a data rate of: 8000 samples/sec x 8 bit/sample=64,000 bps or 64 kbps. CODE: AN INTRODUCTION By Dr. Ernest Simo © 1999 DR. ERNEST SIMO - SPACE2000