调频芯片MC3361设计一个FM解调电路.doc

We will continue to improve the companys internal control system, and steady improvement in ability to manage and control, optimize business processes, to ensure smooth processes, responsibilities in place; to further strengthen internal controls, play a control post independent oversight role of evaluation complying with third-party responsibility; to actively make use of internal audit tools detect potential management, streamline, standardize related transactions, strengthening operations in accordance with law. Deepening the information management to ensure full communication zero resistance. To constantly perfect ERP, and BFS+, and PI, and MIS, and SCM, information system based construction, full integration information system, achieved information resources shared; to expand Portal system application of breadth and depth, play information system on enterprise of Assistant role; to perfect daily run maintenance operation of records, promote problem reasons analysis and system handover; to strengthening BFS+, and ERP, and SCM, technology application of training, improve employees application information system of capacity and level. Humanistic care to ensure zero. To strengthening Humanities care, continues to foster company wind clear, and gas are, and heart Shun of culture atmosphere; strengthening love helped trapped, care difficult employees; carried out style activities, rich employees life; strengthening health and labour protection, organization career health medical, control career against; continues to implementation psychological warning prevention system, training employees health of character, and stable of mood and enterprising of attitude, created friendly fraternity of Humanities environment. To strengthen risk management, ensure that the business of zero risk. To strengthened business plans management, will business business plans cover to all level, ensure the business can control in control; to close concern financial, and coal electric linkage, and energy-saving scheduling, national policy trends, strengthening track, active should; to implementation State-owned assets method, further specification business financial management; to perfect risk tube control system, achieved risk recognition, and measure, and assessment, and report, and control feedback of closed ring management, improve risk prevention capacity. To further standardize trading, and strive to achieve according to law, standardize and fair. Innovation of performance management, to ensure that potential employees zero fly. To strengthen performance management, process control, enhance employee evaluation and levels of effective communication to improve performance management. To further quantify and refine employee standards . Work, full play party, and branch, and members in five type Enterprise construction in the of core role, and fighting fortress role and pioneer model role; to continues to strengthening four good leadership construction, full play levels cadres in enterprise development in the铜陵学院高频电子课程设计系别：电气工程系班级：08通信工程姓名：尹春蕾 学号：指导老师：周老师设计时间：第十七周目录一.设计目的与要求二.设计原理三.设计内容与结果四.心得体会五.参考文献一、 设计目的与要求1、设计目的通过课程设计，使学生加强对高频电子技术电路的理解，学会查寻资料方案比较，以及设计计算等环节。进一步提高分析解决实际问题的能力，创造一个动脑动手独立开展电路实验的机会，锻炼分析解决高频电子电路问题的实际本领，真正实现由课本知识向实际能力的转化；通过典型电路的设计与制作，加深对基本原理的了解，增强学生的实践能力。2、设计要求 用集成调频芯片MC3361设计一个FM解调电路，输入FM信号为中心频率为10.7MHz 、调制信号为1KHz、中频频率为455 KHz。二、 设计原理1、何谓FM解调电路FM解调电路，就是频率的变化f变换成电压的变化v的电路。也就是实现FM调制电路的相反功能。如图所示即为播送用FM接收机的结构图。该结构可分成前端电路、FM中频放大电路、FM立体声电路三个，但FM解调电路是属于FM中频放大电路的一部分，所以准备在检查电路整体工作的同时进行试验。中频放大（二次放大）FM前端中频放大立体声多重解调2、鉴频原理：从调频信号表达式来看，由于随调制信号u(t)成线性变化的瞬时角频率与相位的微积分关系，而相位与电压又是三角函数关系，因此要从调频信号中直接提取与u(t)成正比的电压信号很困难。通常采用两种间接方法。一种方法是先将调频信号通过频幅转换网络变成调频-调幅信号（指瞬时频率和振幅中都含有与调制信号电压成正比分量的高频已调波信号），然后利用包络检波的方式取出调制信号。另一种方法是先将调频信号通过频相转换网络变成调频-调相信号（指瞬时频率和瞬时相位中都含有与调制信号电压成正比分量的高频已调波信号），然后利用鉴相方式取出调制信号。包络检波频幅转换网络UFMUFM-AMU鉴相频相转换网络UFMUFM-AMU3、解调过程分析设输入调频信号为微分器的作用是把调频信号变成调幅调频波。微分器输出为包络检波的作用是从输出信号的幅度变化中检出调制信号。包络检波器输出为称为鉴频灵敏度（），是已调信号单位频偏对应的调制信号的幅度，经低通滤波器后加隔直流电容，隔除无用的直流，得三、设计内容与结果1、MC3361B芯片的介绍从20世纪80年代以来，Motorola公司陆续推出了FM中频电路系列MC3357/3359/3361B/和FM接收电路系列MC3362/3363。它们都采用二次混频，即将输入调频信号的载频先变换到10.7MHz的第一中频，然后降到455KHz的第二中频，再进行鉴频。不同之处在于FM中频电路系列芯片比FM接收电路芯片缺少射频放大和第一混频电路，而FM接收电路系列芯片则相当于一个完整的单片接收机。两个系列均采用双差分正交移相式鉴频方式。现仅介绍MC3361B。从脚输入第一中频为10.7MHz的调频信号，与10.245MHz的晶振进行第二次混频，产生的455KHz调频信号从脚外接的带通滤波器FL1取出，然后由脚进入限幅放大器。脚外接的LC并联网络和片内的10pF小电容组成90频相转换网络。相位鉴频器解调出音频分量由片内放大器放大后，从脚输出，其中一路由外接R3、C7组成的去加重电路送往音频功放，另一路进入脚内的放大器。MC3361B采用了噪声型静噪电路，由V19V30组成的反相器、V31V35组成的静噪触发器和、脚外接元件构成，图二是内部反相放大器和静噪触发器电路图。、脚内接反相放大器，与外接元件R4、R5、R6、C9和C10组成了带通滤波器。其中小电容C9阻止音频分量通过，小电容C10对高频分量提供负反馈通路，从而衰减了高频分量。所以，带通滤波器取出的是位于音频以上一个频率区间内的纯噪声分量。从脚输出的纯噪声经C11耦合，通过开关二极管进入由R10、C12组成的窄带低通滤波器，取出其中的平均分量作为静噪控制电压从脚输入静噪触发器中V32的基极。开关二极管能否导通取决于其负极电位，此处电位由调节可变电阻VR2产生的基准直流电平和脚输出交流噪声相加而成。若没有接收调频信号或信号很弱，则鉴频器输出噪声很大，因此脚输出噪声幅度很大，使二极管负极电位下降，二极管导通，产生的静噪控制电压使脚电位下降，V32截止，V33、V34相继导通，故V35处于饱和导通状态，脚电平接近地电位，从而使音频功放的输入端与地短路，即关闭了音频功放。若接收到音频信号且信号较大，则鉴频器输出噪声很小，因此脚输出噪声幅度很小，使二极管负极电位变化很小，二极管截止，脚电位较高，使V32导通，V33、V34和V35相继截止，脚开路，所以对送往音频功放的解调信号没有影响，即开启了音频功放。2、实验原理图：3、实验结果: 四、心得体会在这次的高频电子线路设计的过程中，自己感到虽然课本上的理论知识掌握的还可以，但是一到实际应用上，具体的课程设计的时候时候，自己不能够很好的应用自己所学的知识去解决一系列的问题。在其他同学的帮助下，以及自己不断的翻阅有关资料，才能够顺利的解决这次的课程设计。通过这次课程设计使我懂得了理论与实践相结合是很重要的，只有理论知识是远远不够的，只有把所学的理论知识与实践相结合起来，从理论中得出结论，才能真正为社会服务，从而提高自己的实际动手能力和独立思考的能力。五、参考文献 通信电路 主 编：沈伟慈 出版社：西安电子科技大学出版社高频电子线路实验指导 主 编：铜陵学院电气工程系高频电路设计与制作 出版社：科学出版社门急诊医技楼外脚手架采用悬挑式单排脚手架，基础回填后改为落地式双排脚手架，脚手架搭设高度为23m。病房医技楼外脚手架采用悬挑双排脚手架，分四次悬挑of backbone backbone role; to full strengthening members youth work, full play youth employees in company development in the of force role; to improve independent Commission against corruption work level, strengthening on enterprise business key link of effectiveness monitored. , And maintain stability. To further strengthen publicity and education, improve the overall legal system. We must strengthen safety management, establish and improve the education, supervision, and evaluation as one of the traffic safety management mechanism. To conscientiously sum up the Olympic security controls, promoting integrated management to a higher level, higher standards, a higher level of development. Employees, today is lunar calendar on December 24, the ox Bell