BPSK Modulation and Demodulation Implemented in Simulink with PN Code Spreading

We conducted a comprehensive experiment for BPSK modulation and demodulation using MATLAB Simulink. The implementation involved generating random signals as the primary modulation source, followed by PN code spreading to enhance signal robustness. The key implementation steps included configuring Bernoulli Binary Generator blocks for random signal generation, PN Sequence Generator blocks for spreading codes, and BPSK Modulator/Demodulator blocks for core modulation/demodulation operations. In the experimental setup, we first generated random binary sequences using Simulink's random signal generators, then applied PN code spreading modulation to increase bandwidth and improve anti-interference capability. The BPSK modulation process involved mapping the spread spectrum signal to phase shifts (0° and 180° for binary 0 and 1 respectively). After transmission through an AWGN channel model, the demodulation process utilized coherent detection with phase synchronization to recover the original signal. The final comparison between the demodulated output and the original random signal demonstrated exceptional consistency, validating the correct implementation of the BPSK modulation/demodulation chain. This experiment successfully showcases Simulink's powerful capabilities in digital communication system simulation and verification, particularly for BPSK systems with spread spectrum techniques. The model effectively demonstrates error-free recovery under specified SNR conditions, making it suitable for educational demonstrations and practical communication system design.