Geology Reference
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y=fft(xx);
maghannrhos2=2*abs(y);
figure;plot(frhos,maghannrhos2/(nn/2));
%apply Hann taper M=0.5N to autocorrelation function
and plot
hannlag50=hann(round(nn/2));
%center the 50% Hann taper in hannwindow
hannwindow=[ ];
hannwindow=zeros(1,nn);
hannwindow=hannwindow';
nstart=nn/4;
nend=3*nn/4;
m=1;
for n=1:nn
if n >= nstart & n < nend
hannwindow(n)=hannlag50(m);
m=m+1;
end
end
%apply the 50% Hann taper stored in hannwindow
hannrhos50=hannwindow.*rhos;
figure;plot(trhos,hannrhos50/max(hannrhos50));
%FFT of 50% Hanned autocorrelation function; plot
modulus
xx=complex(hannrhos50);
y=fft(xx);
maghannrhos502=2*abs(y);
figure;plot(frhos,maghannrhos502/(nn/2));
Figure 4.17a Signal with white noise and red noise. Note: generated noise
series will not be identical to those in the figure.
tt=1:1:2048;
signal=sin(2*pi*tt*0.05)+sin(2*pi*tt*0.055);
noise5=5*randn(2048,1);
rho=0.9;
markov5=markovseries(rho,noise5);
% transpose so values are in a column
markov5=markov5';
signal=signal';
signalnoise5=signal+noise5;
signalmarkov5=signal+markov5;
Figure 4.18 Theoretical autoregressive (AR) and 1/f α spectral noise models:
%arnoisemodel.m for theoretical AR noise models with
rho from 0.0 to 0.9
[farnoise,arnoise]=arnoisemodel();
figure;plot(farnoise,arnoise);
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