【正文】 W=linspace(0,pi,400*pi)。 % title(39。Frequency/Hz39。)。 Wp=[.*pi .*pi]。 %設(shè)置通帶最大最小衰減 [N,Wc]=buttord(Wp,Ws,Ap,As,39。stop39。 %調(diào)用 butter函數(shù)設(shè)計巴特沃斯濾波器 247。168。 %繪出巴特沃斯數(shù)字濾波器的幅頻特性曲線 grid on。 xlabel(39。 在 振幅 的對數(shù)對角頻率的波特圖上 ,從某一邊界角頻率開始 ,振幅隨著角頻率的增加 而逐步減少 ,趨向負(fù)無窮大。 帶阻濾波器減弱 (或減少 )一定頻率范圍信號 , 但容許頻率低于於下限截止頻率和高于上限截止頻率的信號的通過。String39。))。 % plot(f,abs(fx(n+1))*2/N)。 輸入信號為： y=y1+y2=sin(mπ ) +sin(n*π )。 功能：該軟件為 IIR巴特沃斯濾波器的模擬軟件，可根據(jù)參數(shù)的不同，設(shè)計出不同指標(biāo)要求的濾波器。 3， 點 ‘ 輸出波形 ‘按鈕即可輸出相 應(yīng)濾波器的幅頻特性曲線。因為帶通帯阻時， Wp和 Ws都為二維量。 其實用 MATLAB 軟件做實驗是要細(xì)心的，因為很多的語法和常量變量的定義我們都要仔細(xì) ，一個不小心看錯了或者輸入不認(rèn)真是容易出錯誤。 采用 MATLAB設(shè)計濾波器，使原來非常繁瑣復(fù)雜的程序設(shè)計變成了簡單的函數(shù)調(diào) 用，為濾波器的設(shè)和實現(xiàn)開辟了廣闊的天地， 尤其是 Matlab工具箱使各個領(lǐng)域的研究人員可以直觀方便地進(jìn)行科學(xué)研究與工程應(yīng)用。 3 張圣勤 實用教程 北京：機(jī)械工程出版社 2020 年 3 月 課程設(shè)計 第 28 頁 共 44 頁 附錄 界面程序： function varargout = lyl(varargin) % LYL Mfile for % LYL, by itself, creates a new LYL or raises the existing % singleton*. % % H = LYL returns the handle to a new LYL or the handle to % the existing singleton*. % % LYL(39。,39。 gui_State = struct(39。, gui_Singleton, ... 39。, lyl_OutputF, ... 課程設(shè)計 第 29 頁 共 44 頁 39。, [])。 end if nargout [varargout{1:nargout}] = gui_mainf(gui_State, varargin{:})。 % UIWAIT makes lyl wait for user response (see UIRESUME) % uiwait()。String39。amp。defaultUicontrolBackgroundColor39。white39。) returns contents of edit2 as text % str2double(get(hObject,39。 isequal(get(hObject,39。)) set(hObject,39。)。String39。BackgroundColor39。BackgroundColor39。 end function edit4_Callback(hObject, eventdata, handles) % hObject handle to edit4 (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,39。)) returns contents of edit4 as a double % Executes during object creation, after setting all properties. function edit4_CreateF(hObject, eventdata, handles) % hObject handle to edit4 (see GCBO) % eventdata reserved to be defined in a future version of MATLAB % handles empty handles not created until after all CreateFs called % Hint: edit controls usually have a white background on Windows. % See ISPC and COMPUTER. if ispc amp。), get(0,39。,39。String39。amp。defaultUicontrolBackgroundColor39。white39。) returns contents of edit6 as text % str2double(get(hObject,39。 isequal(get(hObject,39。)) set(hObject,39。)。String39。BackgroundColor39。BackgroundColor39。 課程設(shè)計 第 35 頁 共 44 頁 end function edit8_Callback(hObject, eventdata, handles) % hObject handle to edit8 (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,39。)) returns contents of edit8 as a double % Executes during object creation, after setting all properties. function edit8_CreateF(hObject, eventdata, handles) % hObject handle to edit8 (see GCBO) % eventdata reserved to be defined in a future version of MATLAB % handles empty handles not created until after all CreateFs called % Hint: edit controls usually have a white background on Windows. % See ISPC and COMPUTER. if ispc amp。), get(0,39。,39。String39。amp。defaultUicontrolBackgroundColor39。white39。Value39。) returns pushbutton1 contents as cell array % contents{get(hObject,39。 isequal(get(hObject,39。)) set(hObject,39。), get(0,39。)} returns selected item from pushbutton1 % Executes during object creation, after setting all properties. function pushbutton1_CreateF(hObject, eventdata, handles) % hObject handle to pushbutton1 (see GCBO) % eventdata reserved to be defined in a future version of MATLAB % handles empty handles not created until after all CreateFs called % Hint: popupmenu controls usually have a white background on Windows. 課程設(shè)計 第 37 頁 共 44 頁 % See ISPC and COMPUTER. if ispc amp。 % Hints: contents = get(hObject,39。 end % Executes on selection change in pushbutton1. function kj1_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) global t。BackgroundColor39。BackgroundColor39。String39。)。)) set(hObject,39。 isequal(get(hObject,39。) returns contents of edit8 as text % str2double(get(hObject,39。white39。defaultUicontrolBackgroundColor39。amp。String39。,39。), get(0,39。)) returns contents of edit6 as a double % Executes during object creation, after setting all properties. 課程設(shè)計 第 34 頁 共 44 頁 function edit6_CreateF(hObject, eventdata, handles) % hObject handle to edit6 (see GCBO) % eventdata reserved to be defined in a future version of MATLAB % handles empty handles not created until after all CreateFs called % Hint: edit controls usually have a white background on Windows. % See ISPC and COMPUTER. if ispc amp。 end function edit6_Callback(hObject, eventdata, handles) % hObject handle to edit6 (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,39。BackgroundColor39。BackgroundColor39。String39。)。)) set(hObject,39。 isequal(get(hObject,39。) returns contents of edit4 as text % s