QPSK Modulation and Demodulation Generation Program

This MATLAB-based program implements QPSK modulation and demodulation generation. The code generates QPSK signals and performs demodulation functions, fully operable within the MATLAB environment. QPSK (Quadrature Phase Shift Keying) is a fundamental digital modulation technique widely employed in wireless communication systems. The implementation includes key components: signal generation using quadrature carrier modulation, symbol mapping with Gray coding for improved error performance, and coherent demodulation with phase recovery mechanisms. The program demonstrates practical MATLAB functions for waveform generation, constellation diagram plotting, and bit error rate calculation. Through this program, users can gain deeper understanding of QPSK modulation/demodulation principles and implementation methodologies, including important aspects like carrier synchronization, matched filtering, and decision threshold optimization. The code serves as an educational tool and can be adapted for practical applications in communication projects, featuring modular structure that allows easy modification of parameters such as carrier frequency, symbol rate, and signal-to-noise ratio.