Programming Implementation of Pulse Code Modulation (PCM) Technology

This article presents the implementation of Pulse Code Modulation (PCM) through three sequential processes: sampling, quantization, and encoding. Each process is explained in detail with corresponding code implementations.

The sampling process begins with low-pass continuous signal sampling. Using the example signals x=sin(200*t), m=x./(200*t), m=m.*m, we demonstrate the low-pass sampling theorem through MATLAB implementation. The code generates time-domain and frequency-domain plots showing signal characteristics before and after sampling. For band-pass continuous signal sampling, we use x=sin(20*t), m=x./t to illustrate the band-pass sampling theorem, with corresponding visualization of signal behavior in both domains.

The quantization process covers both uniform and non-uniform techniques. For uniform quantization, we implement a 64-level quantizer for amplitude-based sinusoidal signals using quantization step calculation and level assignment algorithms. The non-uniform quantization section demonstrates A-law PCM encoding for sinusoidal inputs, showing how to generate sampling sequences and output code groups through compression characteristic implementation.

The encoding process implements A-law 13-segment approximation method and international standard PCM logarithmic A-law quantization coding. The code includes segment identification, quantization level determination, and binary code generation algorithms that transform quantized values into standardized PCM output sequences.

This enhanced implementation preserves all core technical concepts while providing complete algorithmic descriptions and practical coding approaches suitable for technical documentation.