小功率FM发射机电路的设计案件1doc.doc

小功率FM调频发射机电路的设计 摘要 1933年，美国发明家阿姆斯特朗发明了短波（FM）收音机1939年,发明者阿姆斯特朗在美国建立了第一个FM广播的发射站。同年,调幅收音机开始在美国. 论文是关于小功率调频发射机电路的设计。通常小功率发射机采用直接调频方式，其中调频振荡级主要是产生频率稳定，中心频率符合指标要求的正弦波信号，且其频率受到外加音频信号电压调变，缓冲级主要是对调频振荡信号进行放大，以提供末级所需的激励功率，同时对前后级起有一定的隔离作用，为避免末级功放的工作状态变化而直接影响振荡级的频率稳定度。功放级的任务是确保高效率输出足够大的高频功率，并馈送到天线进行发射。 本设计采用DSP+锁相环技术，频率更加稳定，频率不会随环境变化而产生频飘。 关键词： 小功率调频发射机 直接调频 调频振荡 锁相环  Abstract 1933, the worlds first transmitter was born. American inventors Armstrong invented the short-wave (FM) radio. 1939, the inventor of FM transmitters Armstrong of the United States established the first FM radio transmitters. The same year, the AM radio began sale in the United States. Since then FM transmitter technology has begun to develop rapidly. In all walks of life to be applied, particularly in low-power FM transmitters of more extensive. . The paper is about the low power frequency modulated transmitter electric circuit design. The usual low power transmitter selects the direct-frequency modulation method, frequency modulation vibrates the level mainly is has the frequency to be stable, the center frequency conforms to the target request sine wave signal, also its frequency receives the sur- tonic train signalling voltage regulation, the buffer mainly is vibrates the signal to the frequency modulation to carry on the enlargement, by provides the grid-driving power which the last stage needs, at the same time plays to the around level has the certain isolation role, for avoids the working mode active status change which the last stage merit puts but affecting the vibration level directly the frequency stability. The merit puts the level the duty guarantees the high efficiency output enough big high frequency power, and presents to the antenna carries on the launch. This design USES the DSP + phase locked loop technique, frequency more stable, frequency will not change with the environment and produce frequency wave. Keywords: Small power FM transmitter, Direct FM, FM oscillation, Phase loc