1、目 录 1 绪论 1 2 无线通讯 2 2.1 无线电的发送 3 2.2 无线电的接收 3 2.3 无线通信距离的计算 4 2.4 无线电传输优点 5 2.5 调频波 5 3 系统设计 7 3.1 总体设计方案 7 3.2 方案论证与比较 8 4 单元电路设计 . 10 4.1 音频无线发射电路的设计 . 10 4.2 音频无线接收电路的设计 . 14 4.3 电源模块设计 . 20 5 系统测试 . 21 5.1 分级调试 . 21 5.2 统调 . 22 5.3 发射机频率测试和峰值功率测试 . 22 5.4 测试使用的仪器 . 23 6 结论 24 参考文献 25 致 谢 26 英文资料
2、及中文翻译 27 1 单工无线发射接收系统 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。设计中采用了分立元件构 成音频无线发射电路。 接收机采用第三代立体声放收音机电路 CXA1238 组成的单片收 音机，外围元件极少。它在片内完成了混频、中放、鉴频及立体声解码等功能，接收 机采用电容分压式滤波器，即可提高镜像抑制比，又可使天线达到最佳匹配，具有动 态范围大，调整方便的特点。本设计使用模拟调频技术，在 32MHz 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和接收。系统发射功率大约 20mW，发射
3、 距离大于 5m，本系统可实现无明显失真的语音传输。 关键词：单工无线 调频 语音传输 CXA1238 Simplex wireless emissive and Receiving system Abstract： The remote audio transmission 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
4、code, the frequency modulation can be used to send information. The separate components was adopted to consist audio-frequency wireless emissive circuit in the design. The third generation stereo radio circuit CXA1238 which constitutes the single chip radio was used in the receiver, so the periphera
5、l components are very few. The function such as frequency mixing, supersonic amplification, frequency discrimination and stereo decoding can be achieved in the chip. The electric filter which was based on the capacitance potentiometer was adopted in the receiver . This kind of filter can both raise
6、the mirror-image repression ratio and make the antenna attain its best match. The two characteristics of it are large dynamic and convenient adjustment. The simulating frequency modulation technique was adopted in the design .In the frequency interval of 32MHz,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 5m.There is no obvious distortion in the audio transmission.
