在V1=sin(wx)+a_3sin(3wx+b_3)+a_5sin(5wx+b_5)+a_7sin(7wx+b_7); 信号中加入20dB到40dB信噪比的awgn信号,用matlab编写
时间: 2024-05-26 19:12:57 浏览: 17
答案:
可以按照以下步骤用Matlab编写代码来加入20dB到40dB信噪比的awgn信号:
1. 首先,定义V1信号的波形和参数a、b、w,并生成该信号的时间序列t:
w = 2*pi/1000;
t = 0:0.001:1;
a = [0,0,0,1,0,0,0,1/3,0,0,0,1/5,0,0,0,1/7];
b = [0,0,0,0,0,0,0,pi/2,0,0,0,pi/2,0,0,0,pi/2];
V1 = zeros(size(t));
for k = 1:2:15
V1 = V1 + a((k+1)/2)*sin(k*w*t+b((k+1)/2));
end
2. 接着,为该信号添加20dB到40dB信噪比的awgn信号,可以使用“awgn”函数来实现:
SNR = 20:1:40; % 信噪比范围
V1_noisy = cell(length(SNR),1);
for ii = 1:length(SNR)
V1_noisy{ii} = awgn(V1,SNR(ii),'measured','db'); % 添加噪声
end
3. 最后,可以分别绘制原始信号和不同信噪比下的带噪声信号,并对比它们的频谱图:
figure;
subplot(3,1,1);
plot(t,V1);
title('Original Signal');
xlabel('Time (s)');
ylabel('Amplitude');
for ii = 1:length(SNR)
subplot(3,1,ii+1);
plot(t,V1_noisy{ii});
title(sprintf('Noisy Signal (SNR = %d dB)',SNR(ii)));
xlabel('Time (s)');
ylabel('Amplitude');
end
figure;
subplot(2,1,1);
pwelch(V1,[],[],[],1000,'onesided');
title('Original Signal PSD');
subplot(2,1,2);
for ii = 1:length(SNR)
pwelch(V1_noisy{ii},[],[],[],1000,'onesided');
hold on;
end
legend(sprintfc('SNR = %d dB',SNR));
title('Noisy Signal PSD (with various SNR)');
xlabel('Frequency (Hz)');
ylabel('Power/Frequency');
注意:上述代码仅为示例,实际使用时需要根据具体需求进行适当修改和调整。