This document provides detailed solutions to a Communication Systems Assignment 2, covering a range of topics including matched filters, signal-to-noise ratio (SNR), bit error rate (BER), and Quadrature Phase Shift Keying (QPSK). The solutions include mathematical derivations, Simulink plots, and error probability analysis. Specific problems addressed involve determining the impulse response of a matched filter, analyzing the Fourier transform, calculating maximum SNR, and evaluating the error performance of coherent QPSK systems. The assignment also explores maximum a-posteriori probability decision rules and their application in signal detection. The document further includes MATLAB plots illustrating probability of error performance and symbol error probability curves for QPSK systems with varying alpha values. Finally, the document provides a comprehensive guide to understanding key concepts in communication systems.