DTMF信号的产生与解码.doc

一、 课程设计的目的和任务“数字信号处理”课程是信息和通信工程专业必修的专业技术基础课程。课程以信号与系统作为研究对象，研究对信号进行各种处理和利用的技术。通过该课程的学习，学生应牢固掌握确定性信号和系统的分析方法、相关算法、系统实现等的相关知识的，借助于数字滤波器的设计及实现，学生可掌握数字系统的分析以及设计方法。 数字信号处理是理论性和工程性都很强的学科，本课程设计的目的就是使该课程的理论与工程应用的紧密结合, 使学生深入理解信号处理的内涵和实质。 本课程设计要求学生在理解信号处理的数学原理的基础上，应用计算机编程手段，实现一种信号分析或处理的设计，达到对所学内容融会贯通，综合各部分知识，按照题目要求独立设计完成。二、 课程设计的题目和要求1.课程设计题目：DTMF信号的产生与解码DTMF编解码广泛应用于数字电话拨号，简单通信协议等领域。目前所有的电话和传真机按键都是采用DTMF信号进行编码和传输的，该方案实际是利用模拟信号对数字符号进行编码。该编码方案共使用8个模拟频率对16个符号进行编码，这16个频率分为2个群：高音群和低音群。所以称为双音多频(Dual-Tone Multiple-Frequency)编码，其编码方案如图1。由图可知每个符号由一个高音频率和一个低音频率唯一确定。图1 DTMF信号编码方案对于该信号的产生，我们可以利用数字振荡器来完成。而对这些信号的检测，则可以利用DFT来完成。要注意的是，这里只需要计算16个频点的FFT输出，因此课本上介绍基2或基4算法并不是最优的，这时我们需要采用Goerzel算法完成所需的DFT。当然我们也可以用16个窄带带通滤波器完成，窄带带通滤波器的中心频率就是上述各频率。对窄带滤波器输出信号的输出做判决就可以得到解码的结果。2.设计要求编制程序生成并显示各符号的时域信号和对应的幅频曲线。编程模拟电话拨号过程：输入电话号码，生成各号码的时域信号，给时域信号加噪声，编程对含噪声的电话拨号信号进行解码。编制程序测试编解码程序的正确性。要列出表格，统计拨出的符号的解码成功率。独立完成设计，选择自己熟悉的编程语言编写程序，最好能给出图形界面。3、 设计过程与结果1.在MATLAB中建立一个GUI图形界面，将本课程设计所要实现的功能的一些工具拖进GUI界面，并根据需要修改各个工具的属性，建立的初始界面如图2所示。 图2 GUI图形设计的初始界面2. 打开jink.fig界面所对应的源程序编辑窗口，其中MATLAB会自动生成界面的初始化程序代码以及1D、“解码检测”和“退出”共18个按钮各按钮的函数名和参数功能解释。在这里，我们需要对每个按钮要实现的具体功能编写程序，由于按钮函数较多，且1D数字按钮的功能相似，故可以编写函数供每个这样的函数调用，从而避免程序的繁杂冗余。例如对于点击数字键“1”时要实现的功能的函数可以为如下代码：set(handles.DecodeText,string,); %清空解码显示文本框 Signal = PressKeyDown(handles,1);handles.DTMFSignal = Signal;handles.TelNumber=strcat(handles.TelNumber,1);% Update handles structureguidata(hObject, handles);set(handles.CodeText,string,handles.TelNumber);当运行程序后点击数字键“1”时，pushbutton1_Callback函数会调用PressKeyDown函数，从而完成发出相应的声音、在text1文本框中显示出点击的数字、在axes1和axes2画出对应的图形等功能。点击几个数字或字母键后，在界面中运行的结果如图3所示。 图3 拨号时界面的显示结果3. 在拨号后，要对所接收的拨号信号进行解码检测，检测两个正弦波的频率分别是多少，以判断所对应的十进制数字或字母符号。检测方法有两种，一是用一组滤波器提取所关心的频率，根据两个滤波器的输出信号判断相应的数字或符号，另一是用DFT（FFT）对双音多频信号进行频谱分析，由信号幅度谱判断信号的两个频率，最后确定相应的数字或符号。本设计所编写的相应的解码部分程序代码如下：function pushbutton17_Callback(hObject, eventdata, handles)% hObject handle to pushbutton17 (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA)handles.DecodeTelNumber=; %清空解码字符串变量，开始新一轮解码。keys = 1,2,3,A;4,5,6,B;7,8,9,C;*,0,#,D;for i=1 : length(handles.TelNumber) Signal = dtmf(handles.TelNumber(i); RowNumber = FindLowerFreq(Signal); ColumnNumber = FindHigherFreq(Signal); ResultKey = keys(RowNumber,ColumnNumber); handles.DecodeTelNumber=strcat(handles.DecodeTelNumber,ResultKey); set(handles.DecodeText,string,handles.DecodeTelNumber);endhandles.TelNumber=; %解码完成后，拨号变量清空，方便下一次拨号。点击“解码检测”按钮，进行解码的运行结果如图4所示。 图4 解码后的结果由图4可以看出，在解码的文本框中显示出正确的拨号，表示解码正确。点“退出”键后界面关闭退出。4、 课程设计总结 经过几天的努力，我终于完成了基于MATLAB的DTMF信号的产生与解码课程设计，由于刚上完数字信号处理这门课程，对相关的知识还是比较熟悉，但是对于数字信号处理的实质的理解还是不够深刻，因此刚开始不知如何下手，觉得困难比较多，不过最后经过多次修改和整理，还是完成了。受到自己知识水平的限制，此次课程设计还有很多不足的地方。通过这次课程设计，我发现自己以前关于数字信号处理这门课的看法太片面，课程设计不仅仅是对所学知识的一种检验，更是对自己能力的一种提高，这次课程设计使我明白前面所学的那点知识是非常欠缺的，要学的东西还很多。比如在使用MATLAB制作图形界面上，以前上过这个课程，但没有学其中GUI界面设计部分，这就要求我们去自学。在这次课程设计中，我遇到过很多问题，发现我所学的知识实在有限，好在同学之间可以相互讨论，还可以充分利用网络去查阅相关资料。在整理与修改的过程中，我学到了很多新的知识，也培养了独立思考和设计的能力，树立了对知识应用的信心，相信会对以后的学习工作都有很大的帮助，并且提高了自己的动手实践能力。在这次课程设计的过程中，我得到了许多人的帮助，感谢指导老师耐心的讲解，也感谢在一起讨论的同学，从中我得到了很多好的建议和方法。总之，本次课程设计的过程虽然曲折，但是收获还是蛮大的，这不是对知识的终结，而是我学习更多知识的一个平台。5、 参考文献1. 程耕国，信号与系统，北京：机械工业出版社，2009.42. 高西全、丁玉美，数字信号处理（第三版），西安：西安电子科技大学出版社，2008.83. 李正周，MATLAB数字信号处理与应用，北京：清华大学出版社，20084. 徐明远、刘增力，MATLAB仿真在信号处理中的应用，西安：电子科技大学出版社，20075. 李显宏，MTALAB7.x界面设计与编译技巧，北京：电子工业出版社，20066、 附录源程序代码：function varargout = jink(varargin)% JINK MATLAB code for jink.fig% JINK, by itself, creates a new JINK or raises the existing% singleton*.% H = JINK returns the handle to a new JINK or the handle to% the existing singleton*.% JINK(CALLBACK,hObject,eventData,handles,.) calls the local% function named CALLBACK in JINK.M with the given input arguments.% JINK(Property,Value,.) creates a new JINK or raises the% existing singleton*. Starting from the left, property value pairs are% applied to the GUI before jink_OpeningFcn gets called. An% unrecognized property name or invalid value makes property application% stop. All inputs are passed to jink_OpeningFcn via varargin.% *See GUI Options on GUIDEs Tools menu. Choose GUI allows only one% instance to run (singleton).% See also: GUIDE, GUIDATA, GUIHANDLES % Edit the above text to modify the response to help jink % Last Modified by GUIDE v2.5 01-Jan-2012 13:20:27 % Begin initialization code - DO NOT EDITgui_Singleton = 1;gui_State = struct(gui_Name, mfilename, . gui_Singleton, gui_Singleton, . gui_OpeningFcn, jink_OpeningFcn, . gui_OutputFcn, jink_OutputFcn, . gui_LayoutFcn, , . gui_Callback, );if nargin & ischar(varargin1) gui_State.gui_Callback = str2func(varargin1);end if nargout varargout1:nargout = gui_mainfcn(gui_State, varargin:);else gui_mainfcn(gui_State, varargin:);end% End initialization code - DO NOT EDIT % - Executes just before jink is made visible.function jink_OpeningFcn(hObject, eventdata, handles, varargin)% This function has no output args, see OutputFcn.% hObject handle to figure% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA)% varargin command line arguments to jink (see VARARGIN) % Choose default command line output for jinkhandles.output = hObject;handles.DTMFSignal = ; handles.TelNumber=;handles.DecodeTelNumber=;%保存解码字符串 变量 set(gcf,CurrentAxes,handles.axes1);xlabel(单位：（s）); set(gcf,CurrentAxes,handles.axes2);xlabel(单位：（Hz）); % Update handles structureguidata(hObject, handles); % UIWAIT makes jink wait for user response (see UIRESUME)% uiwait(handles.figure1); % - Outputs from this function are returned to the command line.function varargout = jink_OutputFcn(hObject, eventdata, handles) % varargout cell array for returning output args (see VARARGOUT);% hObject handle to figure% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA) % Get default command line output from handles structurevarargout1 = handles.output; % - Executes on button press in pushbutton1.function pushbutton1_Callback(hObject, eventdata, handles)% hObject handle to pushbutton1 (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA)set(handles.DecodeText,string,); %清空解码显示文本框 Signal = PressKeyDown(handles,1);handles.DTMFSignal = Signal;handles.TelNumber=strcat(handles.TelNumber,1);% Update handles structureguidata(hObject, handles); set(handles.CodeText,string,handles.TelNumber); % - Executes on button press in pushbutton2.function pushbutton2_Callback(hObject, eventdata, handles)% hObject handle to pushbutton2 (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA)set(handles.DecodeText,string,); %清空解码显示文本框 Signal = PressKeyDown(handles,2);handles.DTMFSignal = Signal;handles.TelNumber=strcat(handles.TelNumber,2);% Update handles structureguidata(hObject, handles); set(handles.CodeText,string,handles.TelNumber); % - Executes on button press in pushbutton3.function pushbutton3_Callback(hObject, eventdata, handles)% hObject handle to pushbutton3 (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA)set(handles.DecodeText,string,); %清空解码显示文本框 Signal = PressKeyDown(handles,3);handles.DTMFSignal = Signal;handles.TelNumber=strcat(handles.TelNumber,3);% Update handles structureguidata(hObject, handles); set(handles.CodeText,string,handles.TelNumber); % - Executes on button press in pushbutton4.function pushbutton4_Callback(hObject, eventdata, handles)% hObject handle to pushbutton4 (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA)set(handles.DecodeText,string,); %清空解码显示文本框 Signal = PressKeyDown(handles,4);handles.DTMFSignal = Signal;handles.TelNumber=strcat(handles.TelNumber,4);% Update handles structureguidata(hObject, handles); set(handles.CodeText,string,handles.TelNumber); % - Executes on button press in pushbutton5.function pushbutton5_Callback(hObject, eventdata, handles)% hObject handle to pushbutton5 (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA)set(handles.DecodeText,string,); %清空解码显示文本框 Signal = PressKeyDown(handles,5);handles.DTMFSignal = Signal;handles.TelNumber=strcat(handles.TelNumber,5);% Update handles structureguidata(hObject, handles); set(handles.CodeText,string,handles.TelNumber); % - Executes on button press in pushbutton6.function pushbutton6_Callback(hObject, eventdata, handles)% hObject handle to pushbutton6 (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA)set(handles.DecodeText,string,); %清空解码显示文本框 Signal = PressKeyDown(handles,6);handles.DTMFSignal = Signal;handles.TelNumber=strcat(handles.TelNumber,6);% Update handles structureguidata(hObject, handles); set(handles.CodeText,string,handles.TelNumber); % - Executes on button press in pushbutton7.function pushbutton7_Callback(hObject, eventdata, handles)% hObject handle to pushbutton7 (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA)set(handles.DecodeText,string,); %清空解码显示文本框 Signal = PressKeyDown(handles,7);handles.DTMFSignal = Signal;handles.TelNumber=strcat(handles.TelNumber,7);% Update handles structureguidata(hObject, handles); set(handles.CodeText,string,handles.TelNumber); % - Executes on button press in pushbutton8.function pushbutton8_Callback(hObject, eventdata, handles)% hObject handle to pushbutton8 (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA)set(handles.DecodeText,string,); %清空解码显示文本框 Signal = PressKeyDown(handles,8);handles.DTMFSignal = Signal;handles.TelNumber=strcat(handles.TelNumber,8);% Update handles structureguidata(hObject, handles); set(handles.CodeText,string,handles.TelNumber); % - Executes on button press in pushbutton9.function pushbutton9_Callback(hObject, eventdata, handles)% hObject handle to pushbutton9 (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA)set(handles.DecodeText,string,); %清空解码显示文本框 Signal = PressKeyDown(handles,9);handles.DTMFSignal = Signal;handles.TelNumber=strcat(handles.TelNumber,9);% Update handles structureguidata(hObject, handles); set(handles.CodeText,string,handles.TelNumber); % - Executes on button press in pushbutton10.function pushbutton10_Callback(hObject, eventdata, handles)% hObject handle to pushbutton10 (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA)set(handles.DecodeText,string,); %清空解码显示文本框 Signal = PressKeyDown(handles,*);handles.DTMFSignal = Signal;handles.TelNumber=strcat(handles.TelNumber,*);% Update handles structureguidata(hObject, handles); set(handles.CodeText,string,handles.TelNumber); % - Executes on button press in pushbutton11.function pushbutton11_Callback(hObject, eventdata, handles)% hObject handle to pushbutton11 (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA)set(handles.DecodeText,string,); %清空解码显示文本框 Signal = PressKeyDown(handles,0);handles.DTMFSignal = Signal;handles.TelNumber=strcat(handles.TelNumber,0);% Update handles structureguidata(hObject, handles); set(handles.CodeText,string,handles.TelNumber); % - Executes on button press in pushbutton12.function pushbutton12_Callback(hObject, eventdata, handles)% hObject handle to pushbutton12 (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA)set(handles.DecodeText,string,); %清空解码显示文本框 Signal = PressKeyDown(handles,#);handles.DTMFSignal = Signal;handles.TelNumber=strcat(handles.TelNumber,#);% Update handles structureguidata(hObject, handles); set(handles.CodeText,string,handles.TelNumber); % - Executes on button press in pushbutton13.function pushbutton13_Callback(hObject, eventdata, handles)% hObject handle to pushbutton13 (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA)set(handles.DecodeText,string,); %清空解码显示文本框 Signal = PressKeyDown(handles,A);handles.DTMFSignal = Signal;handles.TelNumber=strcat(handles.TelNumber,A);% Update handles structureguidata(hObject, handles); set(handles.CodeText,string,handles.TelNumber); % - Executes on button press in pushbutton14.function pushbutton14_Callback(hObject, eventdata, handles)% hObject handle to pushbutton14 (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA)set(handles.DecodeText,string,); %清空解码显示文本框 Signal = PressKeyDown(handles,B);handles.DTMFSignal = Signal;handles.TelNumber=strcat(handles.TelNumber,B);% Update handles structureguidata(hObject, handles); set(handles.CodeText,string,handles.TelNumber); % - Executes on button press in pushbutton15.function pushbutton15_Callback(hObject, eventdata, handles)% hObject handle to pushbutton15 (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA)set(handles.DecodeText,string,); %清空解码显示文本框 Signal = PressKeyDown(handles,C);handles.DTMFSignal = Signal;handles.TelNumber=strcat(handles.TelNumber,C);% Update handles structureguidata(hObject, handles); set(handles.CodeText,string,handles.TelNumber); % - Executes on button press in pushbutton16.function pushbutton16_Callback(hObject, eventdata, handles)% hObject handle to pushbutton16 (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA)set(handles.DecodeText,string,); %清空解码显示文本框 Signal = PressKeyDown(handles,D);handles.DTMFSignal = Signal;handles.TelNumber=strcat(handles.TelNumber,D);% Update handles structureguidata(hObject, handles); set(handles.CodeText,string,handles.TelNumber); % - Executes on button press in pushbutton17.function pushbutton17_Callback(hObject, eventdata, handles)% hObject handle to pushbutton17 (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA)handles.DecodeTelNumber=; %清空解码字符串变量，开始新一轮解码。keys = 1,2,3,A;4,5,6,B;7,8,9,C;*,0,#,D;for i=1 : length(handles.TelNumber) Signal = dtmf(handles.TelNumber(i); RowNumber = FindLowerFreq(Signal); ColumnNumber = FindHigherFreq(Signal); ResultKey = keys(RowNumber,ColumnNumber); handles.DecodeTelNumber=strcat(handles.DecodeTelNumber,ResultKey); set(handles.DecodeText,string,handles.DecodeTelNumber);endhandles.TelNumber=; %解码完成后，拨号变量清空，方便下一次拨号。 % Update handles structureguidata(hObject, handles);% RowNumber = FindLowerFreq(handles.DTMFSignal);% ColumnNumber = FindHigherFreq(handles.DTMFSignal);% ResultKey = keys(RowNumber,ColumnNumber);% set(handles.DecodeText,string,char(ResultKey); % PressKeyDown.mfunction Signal = PressKeyDown(handles,key)Signal = dtmf(key);sound(Signal,8000); % 利用声卡播放拨号音set(gcf,CurrentAxes,handles.axes1);NSignal=length(Signal);t=1/8000:1/8000:NSignal/8000;plot(t,Signal);grid; % 画信号的时域波形xlabel(单位：（s）); Spectrum = fft(Signal);Spectrum = fftshift(Spectrum); % 计算信号的频谱N = length(Spectrum); nStep = (2*pi)/(N-1);w = -pi:nStep:pi;set(gcf,CurrentAxes,handles.axes2);plot(w/(2*pi)*8000,abs(Spectrum);grid; %画信号的频谱图axis(-2000,2000,0,200); xlabel(单位：（Hz）); %dtmf.mfunction x = dtmf(key); fs = 8000; N = 0.1 * fs; %信号时间为100ms,N=Tpmin * Fs ； Tpmin根据频率分辨率得到，DTMF信号的最小频率间隔为73HZ,故至少需要110点R = 1; fl = 0; fh = 0; n=0:100;switch key case 1,2,3,A fl = 697; case 4,5,6,B fl = 770; case 7,8,9,C fl = 852;