from spectrum import *
from pylab import plot, log10, linspace, xlim
psd, A, k = minvar(marple_data, 15)
psd = twosided_2_centerdc(psd) # switch positive and negative freq
f = linspace(-0.5, 0.5, len(psd))
plot(f, 10 * log10(psd/max(psd)))
xlim(-0.5, 0.5 )