import spectrum.arma
from pylab import plot, log10, legend
plot(10*log10(spectrum.arma.arma2psd([1,0.5],[0.5,0.5])), label='ARMA(2,2)')
plot(10*log10(spectrum.arma.arma2psd([1,0.5],None)), label='AR(2)')
plot(10*log10(spectrum.arma.arma2psd(None,[0.5,0.5])), label='MA(2)')
legend()