一、擷取代碼方式
二、簡介
1 系統簡介
平台用于模拟通信系統中調制信号并仿真出頻譜圖，主要有幅度調制、角度調制、數字調制及自适應均衡，在相應的調制子產品下，使用者通過輸入相應的參數即可得到輸出結果。是集資訊采集、處理、加工、傳播的重要處理平台。
2 數字調制技術
數字調制是指用數字資料調制模拟信号，主要有三種形式：移幅鍵控法ASK、移頻鍵控法FSK、移相鍵控法PSK。
2.1 幅度鍵控（ASK）
即按載波的幅度受到數字資料的調制而取不同的值，例如對應二進制0，載波振幅為0；對應二進制1，載波振幅為1。調幅技術實作起來簡單，但容易受增益變化的影響，是一種低效的調制技術。在電話線路上，通常隻能達到1200bps的速率。
2.2 頻移鍵控（FSK）
即按數字資料的值（0或1）調制載波的頻率。例如對應二進制0的載波頻率為F1，而對應二進制1的載波頻率為F2。該技術抗幹擾性能好，但占用帶寬較大。在電話線路上，使用FSK可以實作全雙工操作，通常可達到1200bps的速率。
2.3 相移鍵控（PSK）
即按數字資料的值調制載波相位。例如用180相移表示1，用0相移表示0。這種調制技術抗幹擾性能最好，且相位的變化也可以作為定時資訊來同步發送機和接收機的時鐘，并對傳輸速率起到加倍的作用
2.4 QAM
又稱正交幅度調制法。在二進制ASK系統中，其頻帶使用率是1bit／s·Hz，若利用正交載波調制技術傳輸ASK信号，可使頻帶使用率提高一倍。如果再把多進制與其它技術結合起來，還可進一步提高頻帶使用率。能夠完成這種任務的技術稱為正交幅度調制（QAM）。它是利用正交載波對兩路信号分别進行雙邊帶抑制載波調幅形成的。通常有二進制 QAM，四進制QAM（16QAM），八進制QAM（64QAM），……等。
MQAM星座圖如下圖所示：
2.5 PAM
相位幅度調制(Phase Amplitude Modulation),采用多相PSK可以有效提高資料傳輸速率，但受實際電話傳輸網的限制，相移數已達到上限，再要提高資料傳輸速率，隻能另尋它法。PSK和ASK技術的結合，可以解決這個問題。
例如，采用12種相位，其中4種相位每個信号取2種幅度，這樣就得到16種不同的相位幅度離散狀态，可以使一個碼元表示4位二進制資料，進而大大提高了資料傳輸速率。
這種類型的數據機有效資料傳輸率可達9600bps
三、部分源代碼
function varargout = display_signal(varargin)
% DISPLAY_SIGNAL MATLAB code for display_signal.fig
% DISPLAY_SIGNAL, by itself, creates a new DISPLAY_SIGNAL or raises the existing
% singleton*.
%
% H = DISPLAY_SIGNAL returns the handle to a new DISPLAY_SIGNAL or the handle to
% the existing singleton*.
%
% DISPLAY_SIGNAL('CALLBACK',hObject,eventData,handles,...) calls the local
% function named CALLBACK in DISPLAY_SIGNAL.M with the given input arguments.
%
% DISPLAY_SIGNAL('Property','Value',...) creates a new DISPLAY_SIGNAL or raises the
% existing singleton*. Starting from the left, property value pairs are
% applied to the GUI before display_signal_OpeningFcn gets called. An
% unrecognized property name or invalid value makes property application
% stop. All inputs are passed to display_signal_OpeningFcn via varargin.
%
% *See GUI Options on GUIDE's 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 display_signal
% Last Modified by GUIDE v2.5 20-Dec-2011 17:01:23
% Begin initialization code - DO NOT EDIT
gui_Singleton = 1;
gui_State = struct('gui_Name', mfilename, ...
'gui_Singleton', gui_Singleton, ...
'gui_OpeningFcn', @display_signal_OpeningFcn, ...
'gui_OutputFcn', @display_signal_OutputFcn, ...
'gui_LayoutFcn', [] , ...
'gui_Callback', []);
if nargin && ischar(varargin{1})
gui_State.gui_Callback = str2func(varargin{1});
end
if nargout
[varargout{1:nargout}] = gui_mainfcn(gui_State, varargin{:});
else
gui_mainfcn(gui_State, varargin{:});
end
% End initialization code - DO NOT EDIT
% --- Executes just before display_signal is made visible.
function display_signal_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 display_signal (see VARARGIN)
% Choose default command line output for display_signal
handles.output = hObject;
% Update handles structure
guidata(hObject, handles);
% UIWAIT makes display_signal wait for user response (see UIRESUME)
% uiwait(handles.figure1);
% --- Outputs from this function are returned to the command line.
function varargout = display_signal_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 structure
varargout{1} = handles.output;
% --- Executes on selection change in type.
function type_Callback(hObject, eventdata, handles)
% hObject handle to type (see GCBO)
% eventdata reserved - to be defined in a future version of MATLAB
% handles structure with handles and user data (see GUIDATA)
% Hints: contents = cellstr(get(hObject,'String')) returns type contents as cell array
% contents{get(hObject,'Value')} returns selected item from type
% --- Executes during object creation, after setting all properties.
function type_CreateFcn(hObject, eventdata, handles)
% hObject handle to type (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 Fb_Callback(hObject, eventdata, handles)
% hObject handle to Fb (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 Fb as text
% str2double(get(hObject,'String')) returns contents of Fb as a double
% --- Executes during object creation, after setting all properties.
function Fb_CreateFcn(hObject, eventdata, handles)
% hObject handle to Fb (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 四、運作結果
五、matlab版本及參考文獻
1 matlab版本
2014a
2 參考文獻
[1] 沈再陽.精通MATLAB信号處理[M].清華大學出版社，2015.
[2]高寶建,彭進業,王琳,潘建壽.信号與系統——使用MATLAB分析與實作[M].清華大學出版社，2020.