摘 要
利用无线通信信道的远距离语音传输业务，是近年来发展很快的一门技术。由于语音业务对误码不敏感，可以采用调频方式发送信息。调频发射器可以使音频信息传送到附近的任意FM接收机。本设计中使用AT89S52控制调频发射的频率，选择了数码管显示发射的频率状态。选择了ROHM BH1415F集成电路产生调频调制发射信号的频率。芯片的主要特征:体积小，准确性高，而且容易产生发射频率。这个系统的各个部分可以进行深入的独立设计研究，现在把它们组合成一个典型的调频发射系统。 本设计使用模拟调频技术，在88MHz–98MHz的频段上，实现了线路输入语音信号的小功率远距离单工发送。系统发射功率大约20mW，发射距离大于20m，本系统可实现无明显失真的语音传输。
关键词：调频；语音传输；ROHM BH1415
ABSTRACT
The remote audio service code through wireless communication channels is a fast developing technology in recent years. As the audio service code is not sensitive to the mistaken code, the frequency modulation can be used to send information.The FM Transmitter will allow almost any audio source to be transmitted to any nearby FM receiver. The AT89S52 to be used to control the transmission frequency. The LED was chosen, providing enough space for all output situations. The ROHM BH1415F integrated circuit was chosen to create the frequency modulated audio output signal. Chip features include: small size, accuracy, and easily programmed transmission frequency. These system components have been thoroughly researched separately and are now in the process of being integrated to produce a working prototype FM Transmitter. The simulating frequency modulation technique was adopted in the design .In the frequency interval of 88MHz—98 MHz, the audio signals can be sent out and received with the small power in a long distance .The emissive power of the system is about 20mW and the emissive distance is more than 20m.There is no obvious distortion in the audio transmission.
Key Words：frequency modulation；audio transmission； ROHM BH1415F
目 录
1 引言………………………………………………………………………………………………………………. 1
1.1 通信的发展………………………………………………………………………………………….. 1
1.2 广播的发展现状…………………………………………………………………………………… 1
1.3 设计思路……………………………………………………………………………………………… 2
2系统概述………………………………………………………………………………………………………… 3
2.1 系统功能要求………………………………………………………………………………………. 3
2.2系统组成………………………………………………………………………………………………. 3
3 方案论证与比较…………………………………………………………………………………………….. 5
3.1 无线调频发射电路设计方案论证与选择……………………………………………….. 5
3.2 压控振荡器方案论证与选择…………………………………………………………………. 6
4 系统硬件电路的设计……………………………………………………………………………………… 7
4.1 单片机控制电路…………………………………………………………………………………… 7
4.1.1 内部结构……………………………………………………………………………………. 7
4.1.2 引脚功能……………………………………………………………………………………. 9
4.2 调频调制发射电路……………………………………………………………………………… 11
4.2.1 调频调制电路的特点………………………………………………………………… 11
4.2.2 结构图……………………………………………………………………………………… 11
4.2.3 允许的最大值…………………………………………………………………………… 12
4.2.4 工作范围………………………………………………………………………………….. 12
4.2.5 调频调制发射电路的组成…………………………………………………………. 12
4.3 键盘部分……………………………………………………………………………………………. 14
4.3.1 单片机键盘和键盘接口概述……………………………………………………… 14
4.3.2 单片机键盘接口和键功能的实现………………………………………………. 15
4.4 LC振荡电路……………………………………………………………………………………… 16
4.5 调频放大电路…………………………………………………………………………………….. 17
4.6 电源模块设计…………………………………………………………………………………….. 17
4.6.1 单元电源电路设计……………………………………………………………………. 17
4.6.2 直流稳压电源的检测………………………………………………………………… 17
5 系统程序的设计…………………………………………………………………………………………… 18
5.1 主程序……………………………………………………………………………………………….. 18
5.2 延时子程序………………………………………………………………………………………… 19
5.3 LED动态扫描子程序…………………………………………………………………………… 19
5.4 频率数据转换子程序………………………………………………………………………….. 19
5.5 控制命令合成子程序………………………………………………………………………….. 19
5.6 BH1415F字节写入子程序……………………………………………………………………. 20
5.7 查键子程序………………………………………………………………………………………… 21
6 系统调试及性能分析……………………………………………………………………………………. 23
6.1 硬件调试……………………………………………………………………………………………. 23
6.2 软件调试……………………………………………………………………………………………. 23
6.3 发射频率的调试…………………………………………………………………………………. 23
6.4 性能分析……………………………………………………………………………………………. 23
结 论…………………………………………………………………………………………………………… 24
参考文献…………………………………………………………………………………………………………. 25
附录1：原理图……………………………………………………………………………………………….. 26
附录2：程序源代码：…………………………………………………………………………………….. 28
附录3：英文原文……………………………………………………………………………………………. 41
附录4：中文译文……………………………………………………………………………………………. 52
致 谢…………………………………………………………………………………………………………… 59
