写出2ASK、2PSK、2DPSK、2FSK四种调制方式的matlab代码

1. 2ASK（Amplitude Shift Keying）调制方式的matlab代码：

% 2ASK调制
clear; clc;
fc = 100;       %载波频率
fs = 1000;      %采样频率
T = 1/fs;       %采样周期
t = 0:T:1;      %采样时间
Ac = 1;         %载波振幅
fc1 = 10;       %信号频率
fc2 = 20;       %信号频率
As1 = 2;        %信号1振幅
As2 = 4;        %信号2振幅
s1 = As1*sin(2*pi*fc1*t);    %信号1
s2 = As2*sin(2*pi*fc2*t);    %信号2
s = s1 + s2;    %叠加信号
figure(1)
subplot(311)
plot(t, s1), grid on;
title('信号1');
subplot(312)
plot(t, s2), grid on;
title('信号2');
subplot(313)
plot(t, s), grid on;
title('叠加信号');
xlabel('t/s');
ylabel('幅值');

% 2ASK调制
for ii=1:length(t)
    if s(ii) > 0
        m(ii) = 1;
    else
        m(ii) = 0;
    end
end

% 2ASK解调
for ii=1:length(t)
    if m(ii) == 1
        M(ii) = Ac*s(ii);
    else
        M(ii) = 0;
    end
end

figure(2)
subplot(211)
plot(t, s), grid on;
title('调制信号');
subplot(212)
plot(t, M), grid on;
title('解调信号');
xlabel('t/s');
ylabel('幅值');

2. 2PSK（Phase Shift Keying）调制方式的matlab代码：

% 2PSK调制
clear; clc;
fc = 100;       %载波频率
fs = 1000;      %采样频率
T = 1/fs;       %采样周期
t = 0:T:1;      %采样时间
Ac = 1;         %载波振幅
fc1 = 10;       %信号频率
fc2 = 20;       %信号频率
As1 = 2;        %信号1振幅
As2 = 4;        %信号2振幅
s1 = As1*sin(2*pi*fc1*t);    %信号1
s2 = As2*sin(2*pi*fc2*t);    %信号2
s = s1 + s2;    %叠加信号
figure(1)
subplot(311)
plot(t, s1), grid on;
title('信号1');
subplot(312)
plot(t, s2), grid on;
title('信号2');
subplot(313)
plot(t, s), grid on;
title('叠加信号');
xlabel('t/s');
ylabel('幅值');

% 2PSK调制
for ii=1:length(t)
    if s(ii) > 0
        m(ii) = 1;
    else
        m(ii) = -1;
    end
end

% 2PSK解调
for ii=1:length(t)
    if m(ii) == 1
        M(ii) = Ac*sin(2*pi*fc*t(ii));
    else
        M(ii) = Ac*sin(2*pi*fc*t(ii)+pi);
    end
end

figure(2)
subplot(211)
plot(t, s), grid on;
title('调制信号');
subplot(212)
plot(t, M), grid on;
title('解调信号');
xlabel('t/s');
ylabel('幅值');

3. 2DPSK（Differential Phase Shift Keying）调制方式的matlab代码：

% 2DPSK调制
clear; clc;
fc = 100;       %载波频率
fs = 1000;      %采样频率
T = 1/fs;       %采样周期
t = 0:T:1;      %采样时间
Ac = 1;         %载波振幅
fc1 = 10;       %信号频率
fc2 = 20;       %信号频率
As1 = 2;        %信号1振幅
As2 = 4;        %信号2振幅
s1 = As1*sin(2*pi*fc1*t);    %信号1
s2 = As2*sin(2*pi*fc2*t);    %信号2
s = s1 + s2;    %叠加信号
figure(1)
subplot(311)
plot(t, s1), grid on;
title('信号1');
subplot(312)
plot(t, s2), grid on;
title('信号2');
subplot(313)
plot(t, s), grid on;
title('叠加信号');
xlabel('t/s');
ylabel('幅值');

% 2DPSK调制
for ii=1:length(t)
    if ii == 1
        m(ii) = 1;
    else
        if s(ii) > 0
            m(ii) = m(ii-1);
        else
            m(ii) = -m(ii-1);
        end
    end
end

% 2DPSK解调
for ii=1:length(t)
    if ii == 1
        M(ii) = Ac*sin(2*pi*fc*t(ii));
    else
        if m(ii) == m(ii-1)
            M(ii) = M(ii-1);
        else
            M(ii) = Ac*sin(2*pi*fc*t(ii)+pi);
        end
    end
end

figure(2)
subplot(211)
plot(t, s), grid on;
title('调制信号');
subplot(212)
plot(t, M), grid on;
title('解调信号');
xlabel('t/s');
ylabel('幅值');

4. 2FSK（Frequency Shift Keying）调制方式的matlab代码：

% 2FSK调制
clear; clc;
fc = 100;       %载波频率
fs = 1000;      %采样频率
T = 1/fs;       %采样周期
t = 0:T:1;      %采样时间
Ac = 1;         %载波振幅
fc1 = 10;       %信号频率
fc2 = 20;       %信号频率
As1 = 2;        %信号1振幅
As2 = 4;        %信号2振幅
s1 = As1*sin(2*pi*fc1*t);    %信号1
s2 = As2*sin(2*pi*fc2*t);    %信号2
s = s1 + s2;    %叠加信号
figure(1)
subplot(311)
plot(t, s1), grid on;
title('信号1');
subplot(312)
plot(t, s2), grid on;
title('信号2');
subplot(313)
plot(t, s), grid on;
title('叠加信号');
xlabel('t/s');
ylabel('幅值');

% 2FSK调制
for ii=1:length(t)
    if s(ii) > 0
        m(ii) = sin(2*pi*fc1*t(ii));
    else
        m(ii) = sin(2*pi*fc2*t(ii));
    end
end

% 2FSK解调
[b,a] = butter(4,2*fc/fs);
m_filt = filter(b,a,m);
N = length(m_filt);
for ii=1:N
    if m_filt(ii) > 0
        M(ii) = 1;
    else
        M(ii) = 0;
    end
end

figure(2)
subplot(211)
plot(t, s), grid on;
title('调制信号');
subplot(212)
plot(t, M), grid on;
title('解调信号');
xlabel('t/s');
ylabel('幅值');