哈工程数字信号处理实验2013版.doc

数字信号处理实验报告（八）1、 实验名称：音频频谱分析仪设计与实现2、 实验原理：1、信号频率、幅值和相位估计(1)频率(周期)检测对周期信号来说，可以用时域波形分析来确定信号的周期，也就是计算相邻的两个信号波峰的时间差、或过零点的时间差。这里采用过零点(ti)的时间差T(周期)。频率即为f = 1/T，由于能够求得多个T值(ti有多个)，故采用它们的平均值作为周期的估计值。(2)幅值检测在一个周期内，求出信号最大值ymax与最小值ymin的差的一半，即A = (ymax - ymin)/2，同样，也会求出多个A值，但第1个A值对应的ymax和ymin不是在一个周期内搜索得到的，故以除第1个以外的A值的平均作为幅值的估计值。(3)相位检测采用过零法，即通过判断与同频零相位信号过零点时刻，计算其时间差，然后换成相应的相位差。=2(1-ti/T)，x表示x的小数部分，同样，以的平均值作为相位的估计值。频率、幅值和相位估计的流程如图所示。其中tin表示第n个过零点，yi为第i个采样点的值，Fs为采样频率。2、数字信号统计量估计(1) 峰值P的估计在样本数据x中找出最大值与最小值，其差值为双峰值，双峰值的一半即为峰值。P=0.5max(yi)-min(yi)(2)均值估计式中，N为样本容量，下同。(3) 均方值估计(4) 方差估计2、 频谱分析原理时域分析只能反映信号的幅值随时间的变化情况，除单频率分量的简单波形外，很难明确提示信号的频率组成和各频率分量大小，而频谱分析能很好的解决此问题。（1）DFT与FFT对于给定的时域信号y，可以通过Fourier变换得到频域信息Y。Y可按下式计算式中，N为样本容量，t = 1/Fs为采样间隔。采样信号的频谱是一个连续的频谱，不可能计算出所有的点的值，故采用离散Fourier变换(DFT)，即式中，f = Fs/N。但上式的计算效率很低，因为有大量的指数(等价于三角函数)运算，故实际中多采用快速Fourier变换(FFT)。其原理即是将重复的三角函数算计的中间结果保存起来，以减少重复三角函数计算带来的时间浪费。由于三角函数计算的重复量相当大，故FFT能极大地提高运算效率。（2）频率、周期的估计对于Y(kf)，如果当kf = 时，Y(kf)取最大值，则为频率的估计值，由于采样间隔的误差，也存在误差，其误差最大为f / 2。周期T=1/f。从原理上可以看出，如果在标准信号中混有噪声，用上述方法仍能够精确地估计出原标准信号的频率和周期，这个将在下一章做出验证3、频谱图为了直观地表示信号的频率特性，工程上常常将Fourier变换的结果用图形的方式表示，即频谱图。以频率f为横坐标，|Y(f)|为纵坐标，可以得到幅值谱；以频率f为横坐标，arg Y(f)为纵坐标，可以得到相位谱；以频率f为横坐标，Re Y(f)为纵坐标，可以得到实频谱；以频率f为横坐标，Im Y(f)为纵坐标，可以得到虚频谱。根据采样定理，只有频率不超过Fs/2的信号才能被正确采集，即Fourier变换的结果中频率大于Fs/2的部分是不正确的部分，故不在频谱图中显示。即横坐标f 0, Fs/24、模块划分模块化就是把程序划分成独立命名且可独立访问的模块，每个模块完成一个子功能，把这些模块集成起来构成一个整体，可以完成指定的功能满足用户需求。根据人类解决一般问题的经验，如果一个问题由两个问题组合而成，那么它的复杂程度大于分别考虑每个问题时的复杂程度之和，也就是说把复杂的问题分解成许多容易解决的小问题，原来的问题也就容易解决了。这就是模块化的根据。在模块划分时应遵循如下规则：改进软件结构提高模块独立性；模块规模应该适中；深度、宽度、扇出和扇入都应适当；模块的作用域应该在控制域之内；力争降低模块接口的复杂程度；设计单入口单出口的模块；模块功能应该可以预测。3、 实验内容：参考以上原理，查阅相关资料，构建交互界面，设计一个音频频谱分析仪，实现一下功能：(1) 音频信号信号输入，从声卡输入、从WAV文件输入、从标准信号发生器输入；(2) 信号波形分析，包括幅值、频率、周期、相位的估计，以及统计量峰值、均值、均方值和方差的计算；(3) 信号频谱分析，频率、周期的估计，图形显示幅值谱、相位谱、实频谱、虚频谱和功率谱的曲线。4、 实验程序 正弦波 混叠正弦波 方波 三角波 锯齿波 白噪声function varargout = xty(varargin)% XTY M-file for xty.fig% XTY, by itself, creates a new XTY or raises the existing% singleton*.% H = XTY returns the handle to a new XTY or the handle to% the existing singleton*.% XTY(CALLBACK,hObject,eventData,handles,.) calls the local% function named CALLBACK in XTY.M with the given input arguments.% XTY(Property,Value,.) creates a new XTY or raises the% existing singleton*. Starting from the left, property value pairs are% applied to the GUI before guojing_OpeningFunction gets called. An% unrecognized property name or invalid value makes property application% stop. All inputs are passed to guojing_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 xty % Last Modified by GUIDE v2.5 02-Nov-2011 22:54:25 % Begin initialization code - DO NOT EDITgui_Singleton = 1;gui_State = struct(gui_Name, mfilename, . gui_Singleton, gui_Singleton, . gui_OpeningFcn, guojing_OpeningFcn, . gui_OutputFcn, guojing_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 xty is made visible.function guojing_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 guojing (see VARARGIN) % Choose default command line output for guojing handles.output = hObject; % Update handles structureguidata(hObject, handles); % UIWAIT makes xty wait for user response (see UIRESUME)% uiwait(handles.figure1); % - Outputs from this function are returned to the command line.function varargout = guojing_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 soundcard.function soundcard_Callback(hObject, eventdata, handles)% hObject handle to soundcard (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA) % Hint: get(hObject,Value) returns toggle state of soundcardset(findobj(Tag,recordtime),enable,on);h=findobj(Tag,filename);set(h,enable,off);h=findobj(Tag,freq);set(h,enable,off);h=findobj(Tag,amp);set(h,enable,off);h=findobj(Tag,phase);set(h,enable,off);set(handles.channel,enable,off);set(handles.fileopen,enable,off);set(handles.gensig,enable,off);set(handles.wavetype,enable,off);set(handles.add,enable,off);set(handles.startrecord,enable,on); % - Executes on button press in generator.function generator_Callback(hObject, eventdata, handles)% hObject handle to generator (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA) % Hint: get(hObject,Value) returns toggle state of generatorh=findobj(Tag,filename);set(h,enable,off);h=findobj(Tag,freq);set(h,enable,on);h=findobj(Tag,amp);set(h,enable,on);h=findobj(Tag,phase);set(h,enable,on);set(findobj(Tag,recordtime),enable,off);set(handles.channel,enable,off);set(handles.fileopen,enable,off);set(handles.gensig,enable,on);set(handles.wavetype,enable,on);set(handles.add,enable,on);set(handles.startrecord,enable,off); function recordtime_Callback(hObject, eventdata, handles)% hObject handle to recordtime (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA) % Hints: get(hObject,String) returns contents of recordtime as text% str2double(get(hObject,String) returns contents of recordtime as a double % - Executes during object creation, after setting all properties.function recordtime_CreateFcn(hObject, eventdata, handles)% hObject handle to recordtime (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles empty - handles not created until after all CreateFcns called % Hint: edit controls usually have a white background on Windows.% See ISPC and COMPUTER.if ispc & isequal(get(hObject,BackgroundColor), get(0,defaultUicontrolBackgroundColor) set(hObject,BackgroundColor,white);end function filename_Callback(hObject, eventdata, handles)% hObject handle to filename (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA) % Hints: get(hObject,String) returns contents of filename as text% str2double(get(hObject,String) returns contents of filename as a double % - Executes during object creation, after setting all properties.function filename_CreateFcn(hObject, eventdata, handles)% hObject handle to filename (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles empty - handles not created until after all CreateFcns called % Hint: edit controls usually have a white background on Windows.% See ISPC and COMPUTER.if ispc & isequal(get(hObject,BackgroundColor), get(0,defaultUicontrolBackgroundColor) set(hObject,BackgroundColor,white);end % - Executes on selection change in popupmenu1.function popupmenu1_Callback(hObject, eventdata, handles)% hObject handle to popupmenu1 (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA) % Hints: contents = get(hObject,String) returns popupmenu1 contents as cell array% contentsget(hObject,Value) returns selected item from popupmenu1 % - Executes during object creation, after setting all properties.function popupmenu1_CreateFcn(hObject, eventdata, handles)% hObject handle to popupmenu1 (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles empty - handles not created until after all CreateFcns called % Hint: popupmenu controls usually have a white background on Windows.% See ISPC and COMPUTER.if ispc & isequal(get(hObject,BackgroundColor), get(0,defaultUicontrolBackgroundColor) set(hObject,BackgroundColor,white);end function freq_Callback(hObject, eventdata, handles)% hObject handle to freq (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA) % Hints: get(hObject,String) returns contents of freq as text% str2double(get(hObject,String) returns contents of freq as a double % - Executes during object creation, after setting all properties.function freq_CreateFcn(hObject, eventdata, handles)% hObject handle to freq (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles empty - handles not created until after all CreateFcns called % Hint: edit controls usually have a white background on Windows.% See ISPC and COMPUTER.if ispc & isequal(get(hObject,BackgroundColor), get(0,defaultUicontrolBackgroundColor) set(hObject,BackgroundColor,white);end function amp_Callback(hObject, eventdata, handles)% hObject handle to amp (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA) % Hints: get(hObject,String) returns contents of amp as text% str2double(get(hObject,String) returns contents of amp as a double % - Executes during object creation, after setting all properties.function amp_CreateFcn(hObject, eventdata, handles)% hObject handle to amp (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles empty - handles not created until after all CreateFcns called % Hint: edit controls usually have a white background on Windows.% See ISPC and COMPUTER.if ispc & isequal(get(hObject,BackgroundColor), get(0,defaultUicontrolBackgroundColor) set(hObject,BackgroundColor,white);end function phase_Callback(hObject, eventdata, handles)% hObject handle to phase (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA) % Hints: get(hObject,String) returns contents of phase as text% str2double(get(hObject,String) returns contents of phase as a double % - Executes during object creation, after setting all properties.function phase_CreateFcn(hObject, eventdata, handles)% hObject handle to phase (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles empty - handles not created until after all CreateFcns called % Hint: edit controls usually have a white background on Windows.% See ISPC and COMPUTER.if ispc & isequal(get(hObject,BackgroundColor), get(0,defaultUicontrolBackgroundColor) set(hObject,BackgroundColor,white);end % - Executes on button press in startrecord.function startrecord_Callback(hObject, eventdata, handles)% hObject handle to startrecord (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA)Fs=str2double(get(findobj(Tag,samplerate),String);handles.y=wavrecord(str2double(get(findobj(Tag,recordtime),String)*Fs, Fs,double);handles.inputtype=1;guidata(hObject,handles);plot(handles.time,handles.y);title(WAVE);ysize=size(handles.y)set(handles.samplenum,String,num2str(ysize(1); function channel_Callback(hObject, eventdata, handles)% hObject handle to channel (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA) % Hints: get(hObject,String) returns contents of channel as text% str2double(get(hObject,String) returns contents of channel as a double % - Executes during object creation, after setting all properties.function channel_CreateFcn(hObject, eventdata, handles)% hObject handle to channel (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles empty - handles not created until after all CreateFcns called % Hint: edit controls usually have a white background on Windows.% See ISPC and COMPUTER.if ispc & isequal(get(hObject,BackgroundColor), get(0,defaultUicontrolBackgroundColor) set(hObject,BackgroundColor,white);end % - Executes on button press in fileopen.function fileopen_Callback(hObject, eventdata, handles)% hObject handle to fileopen (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA)temp=wavread(get(findobj(Tag,filename),String);channel=str2double(get(handles.channel,String);handles.y=temp(:,channel);handles.inputtype=2;guidata(hObject,handles);plot(handles.time,handles.y);title(WAVE);ysize=size(handles.y)set(handles.samplenum,String,num2str(ysize(1); % - Executes on button press in add.function add_Callback(hObject, eventdata, handles)% hObject handle to add (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA) % Hint: get(hObject,Value) returns toggle state of add % - Executes on button press in gensig.function gensig_Callback(hObject, eventdata, handles)% hObject handle to gensig (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA)Fs=str2double(get(findobj(Tag,samplerate),String);N=str2double(get(findobj(Tag,samplenum),String);x=linspace(0,N/Fs,N);soundtype=get(handles.wavetype,Value);frequency=str2double(get(handles.freq,String);amp=str2double(get(handles.amp,String);phase=str2double(get(handles.phase,String);switch soundtype case 1 y=amp*sin(2*pi*x*frequency+phase); case 2 y=amp*sign(sin(2*pi*x*frequency+phase); case 3 y=amp*sawtooth(2*pi*x*frequency+phase,0.5); case 4 y=amp*sawtooth(2*pi*x*frequency+phase); case 5 y=amp*(2*rand(size(x)-1); otherwise errordlg(Illegal wave type,Choose errer);endif get(handles.add,Value)=0.0 handles.y=y;else handles.y=handles.y+y;endhandles.inputtype=3;guidata(hObject,handles);plot(handles.time,handles.y);title(WAVE);axis(0 N -str2double(get(handles.amp,String) str2double(get(handles.amp,String); % - Executes on button press in WAVfile.function WAVfile_Callback(hObject, eventdata, handles)% hObject handle to WAVfile (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA) % Hint: get(hObject,Value) returns toggle state of WAVfileh=findobj(Tag,filename);set(h,enable,on);h=findobj(Tag,freq);set(h,enable,off);h=findobj(Tag,amp);set(h,enable,off);h=findobj(Tag,phase);set(h,enable,off);set(findobj(Tag,recordtime),enable,off);set(handles.channel,enable,on);set(handles.fileopen,enable,on);set(handles.gensig,enable,off);set(handles.wavetype,enable,off);set(handles.add,enable,off);set(handles.startrecord,enable,off); function samplerate_Callback(hObject, eventdata, handles)% hObject handle to samplerate (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA) % Hints: get(hObject,String) returns contents of samplerate as text% str2double(get(hObject,String) returns contents of samplerate as a double % - Executes during object creation, after setting all properties.function samplerate_CreateFcn(hObject, eventdata, handles)% hObject handle to samplerate (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles empty - handles not created until after all CreateFcns called % Hint: edit controls usually have a white background on Windows.% See ISPC and COMPUTER.if ispc & isequal(get(hObject,BackgroundColor), get(0,defaultUicontrolBackgroundColor) set(hObject,BackgroundColor,white);end fun