SSB对讲机设计报告

单边带调幅对讲机
摘要：本对讲机系统采用单边带调幅(SSB)方式完成语音和数据的传输，通过使 同一机器的发射和接收工作在不同频率实现全双工通信。 超外差结构使接收机接 收灵敏度高并具有自动增益控制（AGC）功能和信号强度指示。使用自制单边 带晶体滤波器滤除载波及上边带以产生单边带信号。 使用数字锁相环产生混频级 本振，使得发射频率可在小范围内调整，实现多频道通信。 关键字：单边带 超外差 全双工 多频道
1. 前言
普通调幅通信系统中，载波经音频信号调制后，包含载波频率和上、下两个 边带， 这两个边带均能用来传输信息。 通常传递信号， 仅需要一个边带就足够了， 但在一般的通信系统中，往往把载波频率和上、下边带一起发送出去，这样在载 波和另一边带中消耗了发射功率中的大部分功率，而且还要占用较宽的通信频 带。虽然 DSB 调制提高了效率，但仍然浪费带宽和发射功率。为了提高通信效 率和节约通信频带，在通信时，可将载波和另一边带去掉，只发送一个边带，这 种通信方式就称为单边带通信。单边带通信的优点是：1、节省功率；2、节约频 带；3、由于单边带发射机不发送载频，提高了保密性。其缺点是设备比较复杂。
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1. 前言 ......................................................................................................................1 2. 总体方案设计 .......................................................................................................1 2.1. 总体方案框图 .............................................................................................1 2.2. 单边带实现方式 .........................................................................................1 2.3. 电路结构设计 .............................................................................................3 2.4. 混频级本振选择 .........................................................................................3 2.5. 调制解调方式选择 .....................................................................................4 2.6. 载波恢复 .....................................................................................................4 2.7. 单片机型号选择 .........................................................................................5 3. 单元模块设计 .......................................................................................................5 3.1. 发射机电路 .................................................................................................5 3.1.1. 调制解调电路....................................................................................6 3.1.2. 语音放大电路....................................................................................6 3.1.3. 平衡调制电路....................................................................................6 3.1.4. 单边带滤波器....................................................................................8 3.1.5. 混频电路 ...........................................................................................8 3.1.6. 高频功放 .........................................................................................10 3.2. 接收机电路 ...............................................................................................10 3.2.1. 高频小信号选频放大 ......................................................................10 3.2.2. 混频电路 .........................................................................................11 3.2.3. 中频放大及 AGC 电路 ....................................................................11 3.2.4. 同步检波电路..................................................................................12 3.2.5. 音频功放 .........................................................................................12 3.3. 实时时钟电路 ...........................................................................................12 3.4. 程序设计 ...................................................................................................13 4. 系统调试.............................................................................................................14 4.1. 单边带晶体滤波器的制作及调试 ............................................................14 4.2. 提取导频 ...................................................................................................15 4.3. 合路器的制作及调试................................................................................16 4.4. 数据传输的调试 .......................................................................................16 4.5. 模拟开关辅助数据传输 ............................................................................17 5. 系统功能及指标参数 .........................................................................................17 5.1. 系统功能 ...................................................................................................17 5.2. 解调单频信号的各参数 ............................................................................17 5.3. 数据传输误码统计 ...................................................................................18 5.4. 测试所用仪器型号 ...................................................................................18 6. 设计总结.............................................................................................................18 7. 参考文献.............................................................................................................18 8. 附录 ....................................................................................................................19
Abstract：The interphones use Single Side Band (SSB) mode to fullfill the sound and data transmission ,and two different frequencies used by the stransimitter and the receiver respectly to make it possible to achieve the full-duplex communication.The sensitivity of the receiver benifits from the superheterodyne architecture.The Automatic Gain Control(AGC) and the indication of the intensity of the signal are also realized.Using the self-made crystal filter to remove the carrier and USB.The digital PLL used by the mixer make it possible to change the frequency in a small scale and communicate in multi-channel. Keywords：SSB Superheterodyne Full-duplex Multi-channel