Periodogram Using Python Script

Periodogram
• Periodogram is the correct name for the
following process*:

• FFT stands for “Fast Fourier Transform”
• The FFT algorithm that can be used to
compute the
part.
• A periodogram is formed after taking the
average magnitude squared of the FFT.

Periodogram: Simple Example

1.n = integer
2.N = array of numbers from 0 to 2^n
3.x = exp(j*2*pi*f*N) + white noise
4.pg = abs(FFT)^2 / n
5.pgs = 10*log10(pg)
 
•Calculates spectrum from Real/Imag
axis, starting at 0 and rotating counter-
clockwise to 2pi (one full revolution)


LIBs NEEDED


Python
matplotlib.pyplot
scipy
numpy


we can plot the periodagram using python using the following script

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from pylab import *

import matplotlib.pyplot as plt

n = 512
N = arange(0,n)
x = exp(2j*pi*0.1*N)+normal(0,0.01,n)
pg = abs(fft(x))**2/n
pgs = 10*log10(pg)
plt.plot(pgs)
 plt.show()



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