import matplotlib.pyplot as plt
import numpy as np
import allantools as allan
# FIXME: /usr/lib/python2.7/dist-packages/numpy/lib/nanfunctions.py:514:
# FutureWarning: In Numpy 1.9 the sum along empty slices will be zero.
# FutureWarning)
def example1():
"""
Compute the GRADEV of a white phase noise. Compares two different
scenarios. 1) The original data and 2) ADEV estimate with gap robust ADEV.
"""
N = 1000
f = 1
y = np.random.randn(1,N)[0,:]
x = [xx for xx in np.linspace(1,len(y),len(y))]
x_ax, y_ax, (err_l, err_h), ns = allan.gradev(y,data_type='phase',rate=f,taus=x)
plt.errorbar(x_ax, y_ax,yerr=[err_l,err_h],label='GRADEV, no gaps')
y[int(np.floor(0.4*N)):int(np.floor(0.6*N))] = np.NaN # Simulate missing data
x_ax, y_ax, (err_l, err_h) , ns = allan.gradev(y,data_type='phase',rate=f,taus=x)
plt.errorbar(x_ax, y_ax,yerr=[err_l,err_h], label='GRADEV, with gaps')
plt.xscale('log')
plt.yscale('log')
plt.grid()
plt.legend()
plt.xlabel('Tau / s')
plt.ylabel('Overlapping Allan deviation')
plt.show()
def example2():
"""
Compute the GRADEV of a nonstationary white phase noise.
"""
N=1000 # number of samples
f = 1 # data samples per second
s=1+5/N*np.arange(0,N)
y=s*np.random.randn(1,N)[0,:]
x = [xx for xx in np.linspace(1,len(y),len(y))]
x_ax, y_ax, (err_l, err_h) , ns = allan.gradev(y,data_type='phase',rate=f,taus=x)
plt.loglog(x_ax, y_ax,'b.',label="No gaps")
y[int(0.4*N):int(0.6*N,)] = np.NaN # Simulate missing data
x_ax, y_ax, (err_l, err_h), ns = allan.gradev(y,data_type='phase',rate=f,taus=x)
plt.loglog(x_ax, y_ax,'g.',label="With gaps")
plt.grid()
plt.legend()
plt.xlabel('Tau / s')
plt.ylabel('Overlapping Allan deviation')
plt.show()
if __name__ == "__main__":
example1()
example2()
