单工无线呼叫系统
【摘要】：
本文主要介绍以AT89S51单片机为核心的一个具有单工语音和英文数据传输功能无线呼
叫系统。该系统的主站主要由单片机与双音频（DTMF）信号编码器以及锁相频率发射机组成；
从站主要由由单片机与高保真调频接收机以及双音频信号解码器组成。主站与从站通过锁相频
率发射机与高保真调频接收机进行通讯。双音频（DTMF）信号编码器与双音频信号解码器能
对调频信号中的双音频（DTMF）信号进行调制与解调。双音频（DTMF）信号编码器与双音
频信号解码器使得本系统具有数据传输能力。在传输语音信号的同时也能传输一定的数据信
息，对于小型的通讯系统具有一定的适用性。
【关键词】：单片机 双音频（DTMF） 锁相环 数据传输
【Abstract】：
This article describes a radio calling system with the functions of single
direction voice and data transmission which is based on the AT89S51 single chip
microcomputer. The system’s master station mainly consists of the single chip, DTMF
signal encoder and PLL frequency transmitter. The slave stations mainly consist of
single chip, Hi-Fi FM receiver and DTMF signal decoder. The master and slave stations
communicate with each other through the PLL frequency transmitter and Hi-Fi FM receiver .
Both of them make the system capable of transmitting the data. The system is suitable for using in
small communications systems due to the ability of its transmitting voice as well as the data in the
same time.
【Key Words】：Single chip microcomputer, DTMF PLL Data transmission
一、方案比较与论证
1、编码方案的选择与论证
方案一：采用双音频（DTMF）信号发生器HT9200B将从单片机要发送的代码转换成双音
频信号，该方案的优点是编码方式简单，可以选择串行和并行两种模式，编程者可以根据自己
