1.软件版本
MATLAB2017b
2.算法结论分析
数字频带传输系统的设计与仿真，使用matlab编写了一个数字频带传输系统，分别实现2ASK、2FSK、2PSK、2DPSK、4ASK、4FSK、4PSK、4DPSK、QPSK，以及4QAM、16QAM和MSK、GMSK这些调制和解调过程。
2ASK，2FSK，2PSK，2DPSK四个二进制的仿真结论如下所示：
4ASK，4FSK，4PSK，4DPSK四个四进制的仿真结论如下所示：
QPSK，4QAM，16QAM三个仿真结果如下所示：
MSK，GMSK两个个仿真结果如下所示：
3.部分源码
clc;
clear all;
close all;
warning off;
Fd=1; %信号数据率
Fc=4; %载波频率
Fs=16; %调制信号的采样频率
N=Fs/Fd;
M=4; %二进制
k=log2(M); %比特数
SNRpBit=0:2:16; %设置仿真信噪比的范围(dB/bit)
SNR=SNRpBit+10*log10(k); %dB/符号
r=10.^(SNRpBit(:).*0.1); %信噪比(线性的)
symPerIter=2048; %每次迭代符号的次数
iters=50; %迭代次数
numSymbTot=symPerIter*iters;
grayencod=bitxor([0:M-1],floor([0:M-1]/2));
[dummy graydecod]=sort(grayencod);
graydecod=graydecod-1;
for(idx2=[1:length(SNR)])
idx=1;
idx2
while((idx<=iters))
%创建信号及Gray编码
msg_orig=randsrc(symPerIter,1,[0:M-1]);
%Gray编码
msg_gr_orig=grayencod(msg_orig+1)';
%2ASK
msg_tx1=dmod(msg_gr_orig,Fc,Fd,Fs,'ask',M); %数字带通调制
msg_rx1=awgn(msg_tx1,SNR(idx2)-10*log10(0.5*N),'measured',[],'dB'); %对调制信号添加高斯白噪声，由于是带通信号，所以噪声功率只有一半
msg_gr_demod1=ddemod(msg_rx1,Fc,Fd,Fs,'ask',M); %解调带通调制信号
msg_demod1=graydecod(msg_gr_demod1+1)'; %Gray码解码
[errBit1(idx) ratBit1(idx)]=biterr(msg_orig,msg_demod1,k); %计算本次迭代的BER
%2FSK
msg_tx2=dmod(msg_gr_orig,Fc,Fd,Fs,'fsk',M);
msg_rx2=awgn(msg_tx2,SNR(idx2)-10*log10(0.5*N),'measured',[],'dB');
msg_gr_demod2=ddemod(msg_rx2,Fc,Fd,Fs,'fsk',M);
msg_demod2=graydecod(msg_gr_demod2+1)';
[errBit2(idx) ratBit2(idx)]=biterr(msg_orig,msg_demod2,k);
%2PSK
msg_tx3=dmod(msg_gr_orig,Fc,Fd,Fs,'psk',M);
msg_rx3=awgn(msg_tx3,SNR(idx2)-10*log10(0.5*N),'measured',[],'dB');
msg_gr_demod3=ddemod(msg_rx3,Fc,Fd,Fs,'psk',M);
msg_demod3=graydecod(msg_gr_demod3+1)';
[errBit3(idx) ratBit3(idx)]=biterr(msg_orig,msg_demod3,k);
%2DPSK
msg_tx4=dpskmod(msg_gr_orig,M);
msg_rx4=awgn(msg_tx4,SNR(idx2)-10*log10(0.5*N),'measured',[],'dB');
msg_gr_demod4=dpskdemod(msg_rx4,M);
msg_demod4=graydecod(msg_gr_demod4+1)';
[errBit4(idx) ratBit4(idx)]=biterr(msg_orig,msg_demod4,k);
idx=idx+1;
end
%计算各次迭代后的平均BER
ratio1(idx2,1)=[mean(ratBit1)];
ratio2(idx2,1)=[mean(ratBit2)];
ratio3(idx2,1)=[mean(ratBit3)];
ratio4(idx2,1)=[mean(ratBit4)];
end
figure;
subplot(121);
semilogy(SNRpBit([1:size(ratio1(:,1),1)]),ratio1(:,1),'b-o');
grid on;
xlabel('SNR(db)');
ylabel('误码率');
legend('仿真的4ASK');
subplot(122);
y0 = abs(fftshift(fft(msg_tx1)));
y1 = abs(fftshift(fft(msg_rx1)));
plot(y1./y0);
legend('频响图');
figure;
subplot(121);
semilogy(SNRpBit([1:size(ratio2(:,1),1)]),ratio2(:,1),'b-o');
grid on;
xlabel('SNR(db)');
ylabel('误码率');
legend('仿真的4FSK');
subplot(122);
subplot(122);
y0 = abs(fftshift(fft(msg_tx2)));
y1 = abs(fftshift(fft(msg_rx2)));
plot(y1./y0);
legend('频响图');
figure;
subplot(121);
semilogy(SNRpBit([1:size(ratio3(:,1),1)]),ratio3(:,1),'b-o');
grid on;
xlabel('SNR(db)');
ylabel('误码率');
legend('仿真的4PSK');
subplot(122);
subplot(122);
y0 = abs(fftshift(fft(msg_tx3)));
y1 = abs(fftshift(fft(msg_rx3)));
plot(y1./y0);
legend('频响图');
figure;
subplot(121);
semilogy(SNRpBit([1:size(ratio4(:,1),1)]),ratio4(:,1),'b-o');
grid on;
xlabel('SNR(db)');
ylabel('误码率');
legend('仿真的4DPSK');
subplot(122);
subplot(122);
y0 = abs(fftshift(fft(msg_tx4)));
y1 = abs(fftshift(fft(msg_rx4)));
plot(y1./y0);
legend('频响图');
A01-86