Geology Reference
In-Depth Information
50
Dirichlet
n=2
0
-50
-100
0
0.025
0.05
Frequency (1/n)
0.075
0.1
(b)
50
Hann
2n
eff
= 5.334
0
-50
-100
0
0.025
0.05
0.075
0.1
Frequency (1/n)
(c)
50
Hann
n
50
= 2(2048)/1024-1=3
2n
eff
= 4.5
0
-50
-100
0
0.025
0.05
0.075
0.1
Frequency (1/n)
(d)
50
Hann
n
50
= 2(2048)/512-1=7
2n
eff
= 9.8
0
-50
-100
0
0.025
0.05
0.075
0.1
Frequency (1/n)
Figure 4.12
Demonstration of the WOSA method on the test time series (Figure 4.10). (a) Unaveraged Dirichlet
periodogram with n = 2 dof from
spectrum.periodogram.m
. (b) Unaveraged Hann periodogram from
spectrum.
periodogram.m
. (c) WOSA-averaged Hann periodogram from
spectrum.welch.m
, Nseg = 1024; d. WOSA-averaged Hann
periodogram from
spectrum.welch.m,
Nseg = 512. The effective dof of the periodograms in (b-d) are given as 2n
eff
.
Normalized frequency output from MATLAB was multiplied by 2 to convert to the frequency scale as in Figure 4.10.
The gray lines are the lower and upper 95% CL of the spectral estimates. As dof increase, the CL becomes more equally
distributed about the spectral estimates.
