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（1）图示
（2）Matlab代码
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
（1）图示
（2）Matlab代码
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); end 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 %% 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‘);
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原文地址：http://www.cnblogs.com/BlueMountain-HaggenDazs/p/4960096.html
