---

Communication System Simulation (MATLAB) | 通信系统仿真

A comprehensive MATLAB simulation suite covering Analog and Digital Communication Principles. 一套完整的《通信原理》MATLAB 仿真方案，涵盖模拟与数字通信系统的核心链路。

---

🌟 Project Highlights | 项目亮点

• Complete Analog Modulation Suite | 完整的模拟调制链路: Implemented AM, DSB, and SSB (USB/LSB) with coherent and non-coherent demodulation.

• 实现了 AM、DSB 以及 SSB（上/下边带）的调制，并包含相干与非相干解调分析。

• Deep FM Physics Verification | 调频物理特性深度验证: Explored wideband FM (WBFM) through Carson's Rule and the Bessel Zero phenomenon.

• 通过实验验证了宽带 FM 的卡森公式带宽理论，并演示了 时的载波零点现象。

• Advanced Hilbert Demodulation | 高级 Hilbert 解调算法: Implemented Instantaneous Phase Demodulation using Hilbert Transform for FM signals.

• 利用 Hilbert 变换提取瞬时相位，实现了比传统微分包络法更具鲁棒性的 FM 解调。

• Pulse Shaping & Spectrum Analysis | 脉冲成形与频谱分析: Comparative study between Rectangular Pulse and Root Raised Cosine (SRRC) shaping in BPSK systems.

• 对比研究了 BPSK 系统中矩形脉冲与根升余弦（SRRC）滚降脉冲对频谱泄露的影响。

---

📂 Repository Structure | 目录结构

├── src/
│   ├── Analog_Modulation/      # 模拟调制模块
│   │   ├── Linear_Mod.m        # AM, DSB, SSB (USB/LSB)
│   │   ├── FM_Basic.m          # FM Modulation & Carson's Rule
│   │   └── FM_Hilbert.m        # Hilbert Phase Demodulation
│   ├── Digital_Modulation/     # 数字调制模块
│   │   └── BPSK_Simulation.m   # BPSK & Pulse Shaping (SRRC)
│   └── utils/                  # Utility Functions | 工具函数
│       ├── T2F.m / F2T.m       # Fourier Transform Tools
│       └── lpf.m               # Ideal Low-pass Filter
└── README.md

---

🔬 Core Theory | 核心理论展示

1. Frequency Modulation (FM)

The FM signal is defined as: 调频信号定义为：

We verified Carson's Rule for bandwidth estimation: 我们验证了用于带宽估计的卡森公式：

2. Digital Baseband Shaping

To suppress spectral leakage in BPSK, we apply Raised Cosine Filtering: 为了抑制 BPSK 的频谱泄露，我们应用了升余弦滤波：

• Benefit: Effectively suppresses sidelobes compared to rectangular pulses.
• 优势: 相比矩形脉冲，能有效抑制旁瓣，减少邻道干扰。

---

📊 Visualizations | 仿真结果

* **注：**: 更多实验图像请自行运行程序

---

🛠️ Requirements & Usage | 环境要求与使用

• MATLAB R2020b or later.
• Signal Processing Toolbox.
• Run: Open any script in src/ and press F5 to execute.

---

Author: [Eric]

---