数字信号调制基于matlab GUI数字信号调制系统含Matlab源码 1030期

Posted 2021-11-09 紫极神光

一、数字信号调制系统简介

二进制数字信号调制原理
数字调制是指用数字基带信号对载波的某些参量进行控制, 使载波的这些参量随基带信号的变化而变化。在通信系统中, 作为载波的正弦波有幅度、频率和相位3个参数, 对应的也就有3种基本的调制方式:调幅、调频和调相。由于数字信号不同与模拟信号的特殊性, 在数字载波通信中, 这3种基本的调制方式分别被称为幅移 (ASK) 、频移键控 (FSK) 和相移键控 (PSK) 。调制信号是二进制数字基带信号时, 这种调制称为二进制数字调制。在二进制数字调制中, 载波的幅度、频率和相位只有两种变化方式。

1 ASK调制
振幅键控是利用载波的幅度变化来传递数字信息, 而其频率和初相位保持不变。二进制幅度键控 (2ASK) 方式是数字调制方式中出现最早也是最简单的一种方法。这种方法最初用于电报系统, 二进制振幅键控常常作为研究其它数字调制方式的基础。2ASK调制信号只有0或1两个电平相乘的, 结果相当于将载频或者关断, 或者接通, 它的实际意义是当调制的数字信号为“1”时, 传输载波;当调制的数字信号为“0”时, 不传输载波。

2ASK信号的一般表达式为:

其中

2 FSK调制
频移键控是利用载波的频率变化来传递数字信息。在2FSK中, 载波的频率随二进制基带信号在f1和f0的两个频率点变化。它的实际意义是当调制的数字信号为“1”或“0”时传输f1或f2频率的载波。

其中ω1=2nf1, ω0=2nf0, θn为频率为f1的载波的初始相位, φn为频率为f0的载波的初始相位。令 为Dn的反码, 即

则2FSK信号可表示为:

3 PSK调制
相移键控是利用载波的相位变化来传递数字信息, 而振幅和频率保持不变。PSK调制时, 载波的相位随调制信号状态不同而改变。如果两个频率相同的载波同时开始振荡, 这两个频率同时达到正最大值, 同时达到零值, 同时达到负最大值, 此时它们就处于“同相”状态;如果一个达到正最大值时, 另一个达到负最大值, 则称为“反相”。一般把信号振荡一次 (一周) 作为360度。如果一个波比另一个波相差半个周期, 我们说两个波的相位差180度, 也就是反相。当传输数字信号时, “1”码控制发0度相位, “0”码控制发180度相位。相移键控有很好的抗干扰性, 在有衰落的信道中也能获得很好的效果。

二、部分源代码

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-2020 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



function Fc_Callback(hObject, eventdata, handles)
% hObject    handle to Fc (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 Fc as text
%        str2double(get(hObject,'String')) returns contents of Fc as a double


% --- Executes during object creation, after setting all properties.
function Fc_CreateFcn(hObject, eventdata, handles)
% hObject    handle to Fc (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 Bit_Callback(hObject, eventdata, handles)
% hObject    handle to Bit (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 Bit as text
%        str2double(get(hObject,'String')) returns contents of Bit as a double


% --- Executes during object creation, after setting all properties.
function Bit_CreateFcn(hObject, eventdata, handles)
% hObject    handle to Bit (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 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)


tempobj=findobj(gcbf,'tag','type');
modu_type=get(tempobj,'value');

fc=eval(get(handles.Fc,'String'));              %可选参数设置
B=str2double(get(handles.Fb,'String'));
DisBit=str2double(get(handles.Bit,'String'));

 switch(modu_type)
     case 1
            nper=B/fc;       %一个码元中所包含的载波周期数
            nsamp=128;       %过采样率
            fs=nsamp*B;      %采样率
            Ts=1/fs;         %采样周期
            NumBit=1024;       %数据位数

            %数字基带信号产生
            Data=randint(1,NumBit);
            NumSample=NumBit*nsamp;    %总采样点数
            signal=zeros(1,NumSample);
            start=1;
            for i=1:NumBit
                if(Data(i))
                    signal(start:start+nsamp-1)=1;
                end
                start=start+nsamp;
            end
            t=0:Ts:Ts*(NumSample-1);
            ASK_signal=signal.*sin(2*pi*fc*t);

三、运行结果

四、matlab版本及参考文献

1 matlab版本
2014a

2 参考文献
[1] 沈再阳.精通MATLAB信号处理[M].清华大学出版社，2015.
[2]高宝建,彭进业,王琳,潘建寿.信号与系统——使用MATLAB分析与实现[M].清华大学出版社，2020.
[3]王文光,魏少明,任欣.信号处理与系统分析的MATLAB实现[M].电子工业出版社，2018.
[4]曾祥龙,梁清梅,索丽敏.运用MATLAB实现对数字信号调制的仿真[J].黑龙江科技信息. 2009,(32)