韦尔奇频谱估计值

打开实时脚本

创建一个信号，该信号由三个含噪正弦波和一个以 200 kHz 进行 0.1 秒采样的啁啾组成。这些正弦波的频率分别为 1 kHz、10 kHz 和 20 kHz。这些正弦波具有不同振幅和噪声电平。无噪声啁啾的频率从 20 kHz 开始，并在采样期间线性增大到 30 kHz。

Fs = 200e3; 
Fc = [1 10 20]'*1e3; 
Ns = 0.1*Fs;

t = (0:Ns-1)/Fs;
x = [1 1/10 10]*sin(2*pi*Fc*t)+[1/200 1/2000 1/20]*randn(3,Ns);
x = x+chirp(t,20e3,t(end),30e3);

计算信号的韦尔奇 PSD 估计值以及最大值保持和最小值保持频谱。绘制结果。

[pxx,f] = pwelch(x,[],[],[],Fs);
pmax = pwelch(x,[],[],[],Fs,'maxhold');
pmin = pwelch(x,[],[],[],Fs,'minhold');

plot(f/1000,pow2db(pxx))
hold on
plot(f/1000,pow2db([pmax pmin]),':')
hold off
xlabel('Frequency (kHz)')
ylabel('PSD (dB/Hz)')
legend('pwelch','maxhold','minhold')
grid

Figure contains an axes object. The axes object with xlabel Frequency (kHz), ylabel PSD (dB/Hz) contains 3 objects of type line. These objects represent pwelch, maxhold, minhold.

重复此过程，这次计算中心化功率谱估计值。

[pxx,f] = pwelch(x,[],[],[],Fs,'centered','power');
pmax = pwelch(x,[],[],[],Fs,'maxhold','centered','power');
pmin = pwelch(x,[],[],[],Fs,'minhold','centered','power');

plot(f/1000,pow2db(pxx))
hold on
plot(f/1000,pow2db([pmax pmin]),':')
hold off
xlabel('Frequency (kHz)')
ylabel('Power (dB)')
legend('pwelch','maxhold','minhold')
title('Centered Power Spectrum Estimates')
grid

Figure contains an axes object. The axes object with title Centered Power Spectrum Estimates, xlabel Frequency (kHz), ylabel Power (dB) contains 3 objects of type line. These objects represent pwelch, maxhold, minhold.

另请参阅

chirp | pow2db | pwelch