小功率调频发射机研究
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本科毕业设计说明书
小功率调频发射机研究
DESIGN OF LITTLE POWER FM TRANSMITTER
学院（部）： 通信工程
专业班级： 通信10-1班
学生姓名： 江传民
指导教师： 钟鸣宇 讲师
2014年 5月 20 日
安徽理工大学毕业设计
I 小功率调频发射机
摘要
本设计为小功率调频发射机，其实就是一个小型电台，可以将声音加载到无线电信号上发射出去,用合适的收音机就能接收，并且可以从扬声器中放出声音。
本次设计的发射机由由三部分构成：调频振荡级、缓冲隔离级、功率激励和末级功放级。其基本工作原理是通过振荡级产生稳定的5MHz信号，麦克风采集到人的音频信号，将音频信号加载到5MHz的载波上，通过缓冲隔离级使末级功放和前一级的调频振荡相分开,避免末级功放对振动频率产生影响，提高频率稳定度,功率增益如果都集中在末级功放容易产生自激，故先通过功率激励级对信号的微弱电压进行放大，末级功放一般工作在丙类状态,工作效率ηA大于50%，信号功率大于500mW。
关键词:发射机，调频，无线话筒，小功率 安徽理工大学毕业设计
II LOW POWER FM TRANSMITTER
ABSTRACT
The design for the low power FM transmitter, is in fact a small radio
station, voice can be loaded into the launch out radio signals, use a
suitable radio can receive, and can emit sound from the speaker.
The design of the transmitter by consists of three parts: FM oscillation,
cushioning isolation levels, power drive and at the end of the power
amplifier.Its basic working principle is through the oscillation magnitude
5 MHZ signal stability, the microphone to the audio signal, the audio
signal is loaded on the carrier to 5 MHZ, through buffer isolation level
the level at the end of the power amplifier and the former separate from
primary frequency modulation of the oscillation, avoid the last stage
amplifier influence on the vibration frequency, to improve the frequency
stability, power gain if are concentrated in the last stage amplifier is easy
to produce self-excited, so the first of the weak voltage signal through the
power stage of amplification, the last stage amplifier generally work in c
class status, the efficiency eta A greater than 50%, signal power is greater
than 500 mw, finally will signal the antenna to launch out.
KEYWORDS: transmitter;FM, wireless microphone;low power安徽理工大学毕业设计
i 目录
摘要（中文）........................................................ I
ABSTRACT（英文）................................................... II
1 绪论.............................................................. 1
1.1 FM发射机的概念.............................................. 1
1.2 FM发射机的现状.............................................. 2
1.3 设计技术指标 ................................................ 3
2 总体方案设计...................................................... 5
2.1调频振荡级................................................... 5
2.2缓冲级....................................................... 5
2.3功率激励和末级功放级......................................... 5
2.2整机电路框图................................................. 6
3 单元电路设计...................................................... 7
3.1 功率激励和末级功放设计 ...................................... 7
3.1.1末级功放级 ............................................. 7
3.1.2功率激励级 ............................................. 8
3.1.3末级功放电路参数计算 ................................... 9
3.1.4功率激励级电路参数计算 ................................ 12
3.2缓冲隔离级.................................................. 15
3.2.1 缓冲隔离级电路原理.................................... 15
3.2.2静态工作点的计算 ...................................... 15
3.3调频振荡级.................................................. 17
3.3.1 调频的方案分析与选择.................................. 17
3.3.2变容二极管相关特性 .................................... 18
3.3.3变容管调相电路参数计算 ................................ 19
3.3.4三级单回路变容管调相电路 .............................. 20
3.4 天线的相关知识及设计 ....................................... 20
3.4.1.天线的输入阻抗........................................ 21
3.4.2.天线的增益............................................ 21
3.4.3.天线的极化方式........................................ 21
3.4.4.天线的设计方案........................................ 21
4 整机电路模拟测试................................................. 23
4.1 Protel和Multisim简介...................................... 23
4.2调频振荡级电路测试.......................................... 23
4.3整机模拟.................................................... 24
总结............................................................... 26
参考文献........................................................... 27
致谢............................................................... 28
附录一 整机电路图.................................................. 29
附录二 元器件参数表................................................ 30
