QPSK Modulation and Demodulation Implementation with MATLAB Code

This program implements a complete QPSK modulator and demodulator using MATLAB programming language. The system demonstrates digital signal generation and demodulation processes suitable for digital communication applications. Key implementation components include: - Signal generation: Creates binary data streams using random number generators - Carrier generation: Produces orthogonal carriers using cosine and sine functions with specified frequencies - Modulation process: Implements quadrant mapping through constellation diagrams using phase-shift keying - Channel transmission: Simulates AWGN channel conditions with configurable SNR parameters - Demodulation: Employs coherent detection with matched filters and phase recovery algorithms - Signal reconstruction: Includes error calculation and BER performance analysis The program provides practical understanding of QPSK principles through: - Visual constellation diagram display showing signal points - Waveform generation for time-domain analysis - Bit error rate (BER) vs SNR performance curves - Comparative analysis with theoretical QPSK performance This implementation serves as an educational tool for communication system experiments and research, featuring modular code structure with configurable parameters for carrier frequency, sampling rate, and noise levels.