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import numpy as np
import numpy.fft as fft
import sys
from matplotlib import pyplot as plt
import math
def blackman_harris(npoints):
x=np.arange(0,npoints)
y= 0.35875 - 0.48829*np.cos(2*np.pi*x/npoints) + 0.14128*np.cos(4*np.pi*x/npoints) - 0.01168*np.cos(6*np.pi*x/npoints)
return y
def plot_spect(indata, window=True):
for wf, fs in indata:
print(sum(wf))
npoints = len(wf)
divfact = npoints/2
if window:
wind = blackman_harris(npoints)
wf = wf*wind*wind
divfact = sum(wind)/2
print(npoints)
t = np.linspace(0, npoints/fs, npoints, endpoint=False)
f = np.linspace(0, fs/2.0, math.floor(npoints/2))
valfft = fft.fft(wf)
cut = valfft[0:math.floor(npoints/2)]
ampl = 20*np.log10(np.abs(cut)/divfact)
phase = 180/np.pi*np.angle(cut)
#plt.subplot(2,1,1)
plt.figure(1)
plt.plot(f, ampl)
#plt.subplot(2,1,2)
#plt.semilogx(f, phase)
#plt.gca().set(xlim=(10, srate/2.0))
#plt.subplot(2,1,2)
plt.figure(2)
plt.plot(wf)
plt.figure(3)
plt.plot(np.diff(wf,5))
plt.show()
file_in = sys.argv[1]
channels = int(sys.argv[2])
bits = int(sys.argv[4])
srate = int(sys.argv[3])
if bits == 64:
values = np.fromfile(file_in, dtype=float)
elif bits == 32:
values = np.fromfile(file_in, dtype=np.float32)
# Let's look at the first channel only..
values = values.reshape((-1,channels))
values = values[:,0]
plot_spect([(values, srate)], window=True)
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