function [ s_t ,bb_t,bits] = psk2_module( nSym ,Rb,fs,fc,Ac )
%UNTITLED7 此处显示有关此函数的摘要
%   此处显示详细说明
%nSym = 300;   % 信息长度
%Rb = 200;     % 信息速率
%fs = 48e3;    % 采样率
%fc = 4e3;     % 载波频率
%Ac = 1;       % 载波幅度
%s_t           % 已调波形
%bb_t          % 码型时域波形
%bb            % 码型%%
%产生信号
% 随机产生二进制信息
bits = randint(nSym,1);
% 产生不归零码
bb = 2 * bits - 1; %%
%产生码型
% 每个符号包含的样点数
sample_bit = fs / Rb;
% 时间
t = (0:sample_bit*nSym-1)'/fs;
% 产生不归零码的时域波形
bb_t = reshape(repmat(bb', sample_bit, 1), sample_bit*nSym, 1); %%
%调制
% 产生载波信号
c_t = Ac*cos(2*pi*fc*t);
% 调制
s_t = bb_t .* c_t; end

function [ bits,bb_t] = psk2_remodule( Rb,fs,fc,s_t)
%UNTITLED11 此处显示有关此函数的摘要
%   此处显示详细说明
% Rb = 200;       % 信息速率
% fs = 48e3;      % 采样率
% fc = 4e3;       % 载波频率
% s_t             % 调制波形% bit_s           % 抽样判决之后
% bb_t            % 抽样判决之前r_t = s_t; % 每个符号包含的样点数
sample_bit = fs/Rb;
% 时间
t = (0:length(r_t)-1)'/fs; % 产生同频同相载波信号
c_t = cos(2*pi*fc*t);% FIR群延迟，也是阶数一半
group_delay = 50;
b = fir1(group_delay*2, Rb/(fs/2)); % 主瓣占带宽Rb，这里可以放宽
bb_t = filter(b,1, r_t .* c_t); % 混频并滤波 % 抽样点下标
idx_decision = round(1+group_delay+sample_bit/2):sample_bit:length(r_t);
% 取得抽样点
val_decision = bb_t(idx_decision); % 判决
bits = zeros(length(val_decision),1);
bits(val_decision > 0) = 1; end

clc,clear;nSym = 1000;    % 信息长度
Rb = 1e3;      % 信息速率
fs = 48e3;     % 采样率
fc = 5e3;      % 载波频率
Ac = 1;        % 载波幅度%%
[s_t ,bb_t,bb] = psk2_module( nSym ,Rb,fs,fc,Ac );
t = (0 : length(s_t) - 1) / fs' ;%%
%绘制已调波形
figure();
plot(t,s_t);
title('2PSK时域波形');
xlabel('time(t)');
ylabel('y');%绘制功率谱
powerF_draw(s_t,fs);%%
%发送端码型变换后的波形
figure();
subplot(2,1,1);
plot(t,bb_t);
axis([min(t),max(t),-1.2,1.2]);
title('发送端码型波形');
xlabel('time(t)');
ylabel('y');%接收端抽样判决前的波形
subplot(2,1,2);
[bits,rbb_t] = psk2_remodule(Rb,fs,fc,s_t);
plot(t,rbb_t);
title('接收端码型波形');
xlabel('time(t)');
ylabel('y');%%
%眼图
eyediagram(rbb_t,4*fs/Rb); %取四个Bit
title('无信道噪声');%小噪声
s_pow = sum(s_t.^2) / length(s_t);
n_pow = 0.01 * s_pow;
n_t = bandlimit_noise(length(s_t),fs,fc,2*Rb,n_pow);
[bits_low_noise,rbb_t_low_noise] = psk2_remodule(Rb,fs,fc,s_t + n_t);
eyediagram(rbb_t_low_noise,4*fs/Rb);
title('小信道噪声');%大噪声
n_pow = 0.5 * s_pow;
n_t = bandlimit_noise(length(s_t),fs,fc,2*Rb,n_pow);
[bits_high_noise,rbb_t_high_noise] = psk2_remodule(Rb,fs,fc,s_t + n_t);
eyediagram(rbb_t_high_noise,4*fs/Rb);
title('大信道噪声');%%
%2PSK通信系统评估
snr_i = (-3:1:8)'; % SNR输入(dB)%计算噪声功率
n_pow = s_pow ./ (10.^(snr_i ./ 10));%初始化储存
number = zeros(1,length(snr_i));
ratio = zeros(1,length(snr_i));%计算SNR
for i=1:length(snr_i)n_t = bandlimit_noise(length(s_t),fs,fc,2*Rb,n_pow(i));[bits,rbb_t] = psk2_remodule(Rb,fs,fc,s_t + n_t);[number(i),ratio(i)] = symerr(bits,bb(1:nSym-1));
end%绘图
figure();
plot(snr_i,ratio*100);
title('误码率曲线');
xlabel('snr_i(dB)');
ylabel('误码率(%)');

function [ s_t ,bb_t,bits] = dpsk2_module( nSym ,Rb,fs,fc,Ac )
%UNTITLED7 此处显示有关此函数的摘要
%   此处显示详细说明
%nSym = 300;   % 信息长度
%Rb = 200;     % 信息速率
%fs = 48e3;    % 采样率
%fc = 4e3;     % 载波频率
%Ac = 1;       % 载波幅度
%s_t           % 已调波形
%bb_t          % 码型时域波形
%bits          % 码型%%
%产生信号
% 随机产生二进制信息
bits = randint(nSym,1);%产生差分码
bits_d = zeros(nSym+1,1);
for i=1:length(bits)bits_d(i+1) = mod(bits_d(i) + bits(i),2);
end% 产生不归零码
bb = 2 * bits_d - 1; %%
%产生码型
% 每个符号包含的样点数
sample_bit = fs / Rb;
% 时间
t = (0:sample_bit*(nSym+1)-1)'/fs;
% 产生不归零码的时域波形
bb_t = reshape(repmat(bb', sample_bit, 1), sample_bit* (nSym+1), 1); %%
%调制
% 产生载波信号
c_t = Ac*cos(2*pi*fc*t);
% 调制
s_t = bb_t .* c_t; end

function [ bits,bb_t] = dpsk2_remodule( Rb,fs,fc,s_t)
%UNTITLED11 此处显示有关此函数的摘要
%   此处显示详细说明
% Rb = 200;       % 信息速率
% fs = 48e3;      % 采样率
% fc = 4e3;       % 载波频率
% s_t             % 调制波形% bit_s           % 抽样判决之后
% bb_t            % 抽样判决之前r_t = s_t; % 每个符号包含的样点数
sample_bit = fs/Rb;
% 时间
t = (0:length(r_t)-1)'/fs; % 产生同频同相载波信号
c_t = cos(2*pi*fc*t);% FIR群延迟，也是阶数一半
group_delay = 50;
b = fir1(group_delay*2, Rb/(fs/2)); % 主瓣占带宽Rb，这里可以放宽
bb_t = filter(b,1, r_t .* c_t); % 混频并滤波 % 抽样点下标
idx_decision = round(1+group_delay+sample_bit/2):sample_bit:length(r_t);
% 取得抽样点
val_decision = bb_t(idx_decision); % 判决
bits_d = zeros(length(val_decision),1);
bits_d(val_decision > 0) = 1;
bits = zeros(length(bits_d)-1,1);
for i=1:length(bits)bits(i) = mod(bits_d(i) + bits_d(i+1),2);
endend

clc,clear;nSym = 1000;    % 信息长度
Rb = 1e3;      % 信息速率
fs = 48e3;     % 采样率
fc = 5e3;      % 载波频率
Ac = 1;        % 载波幅度%% 产生2PSK信号
[s_t,bb_t,bb] = psk2_module( nSym ,Rb,fs,fc,Ac );%% 产生2DPSK信号
[s_d_t,bb_d_t,bb_d] = dpsk2_module( nSym ,Rb,fs,fc,Ac );%% 绘制发送端差分编码前后的波形
figure()
%发送端差分编码前离散序列
subplot(2,1,1);
stem(bb_d);
axis([-5,nSym+5,-1.2,1.2]);
title('发送端差分编码前离散序列');
xlabel('time(t)');
ylabel('y');%发送端差分不归零编码后离散序列
subplot(2,1,2);
stem(bb_d_t(1:fs/Rb:length(bb_d_t)));
axis([-5,nSym+5,-1.2,1.2]);
title('发送端差分不归零编码后离散序列');
xlabel('time(t)');
ylabel('y');[bits_d,rbb_d_t] = dpsk2_remodule(Rb,fs,fc,s_d_t);%% 2PSK通信系统评估
s_pow = sum(s_t.^2) / length(s_t);
snr_i = (-3:1:8)'; % SNR输入(dB)
%计算噪声功率
n_pow = s_pow ./ (10.^(snr_i ./ 10));%初始化储存
number = zeros(1,length(snr_i));
ratio = zeros(1,length(snr_i));%计算SNR
for i=1:length(snr_i)n_t = bandlimit_noise(length(s_t),fs,fc,2*Rb,n_pow(i));[bits,rbb_t] = psk2_remodule(Rb,fs,fc,s_t + n_t);[number(i),ratio(i)] = symerr(bits,bb(1:nSym-1));
end%% 2DPSK通信系统评估
s_d_pow = sum(s_d_t.^2) / length(s_d_t);
snr_i = (-3:1:8)'; % SNR输入(dB)%计算噪声功率
n_d_pow = s_d_pow ./ (10.^(snr_i ./ 10));%初始化储存
number_d = zeros(1,length(snr_i));
ratio_d = zeros(1,length(snr_i));%计算SNR
for i=1:length(snr_i)n_d_t = bandlimit_noise(length(s_d_t),fs,fc,2*Rb,n_d_pow(i));[bits_d,rbb_d_t] = dpsk2_remodule(Rb,fs,fc,s_d_t + n_d_t);[number_d(i),ratio_d(i)] = symerr(bits_d,bb_d(1:nSym-1));
end%绘图
figure()
hold on;
plot(snr_i,ratio*100,'b');
plot(snr_i,ratio_d*100,'r');
title('2PSK和2DPSK误码率曲线对比');
xlabel('snr_i(dB)');
ylabel('误码率(%)');
legend('2PSK','2DPSK');