Allan deviation and related time/frequency statistics

## Project description

A python library for calculating Allan deviation and related time & frequency statistics. LGPL v3+ license.

Input data should be evenly spaced observations of either fractional frequency, or phase in seconds. Deviations are calculated for given tau values in seconds.

Function

Description

Allan deviation

Overlapping Allan deviation

mdev()

Modified Allan deviation

tdev()

Time deviation

hdev()

ohdev()

totdev()

Total deviation

mtotdev()

Modified total deviation

ttotdev()

Time total deviation

htotdev()

theo1()

Theo1 deviation

mtie()

Maximum Time Interval Error

tierms()

Time Interval Error RMS

Gap resistant overlapping Allan deviation

Noise generators for creating synthetic datasets are also included:

• violet noise with f^2 PSD

• white noise with f^0 PSD

• pink noise with f^-1 PSD

• Brownian or random walk noise with f^-2 PSD

More details on available statistics and noise generators : full list of available functions

see /tests for tests that compare allantools output to other (e.g. Stable32) programs. More test data, benchmarks, ipython notebooks, and comparisons to known-good algorithms are welcome!

## Installation

Install from pypi:

pip install allantools

Latest version + examples, tests, test data, iPython notebooks : clone from github, then install

python setup.py install

(see python setup.py –help install for install options)

These commands should be run as root for system-wide installation, or you can use the –user option to install for your account only. Exact command names may vary depending on your OS / package manager / target python version.

## Basic usage

### Minimal example, phase data

We can call allantools with only one parameter - an array of phase data. This is suitable for time-interval measurements at 1 Hz, for example from a time-interval-counter measuring the 1PPS output of two clocks.

>>> import allantools
>>> x = allantools.noise.white(10000)        # Generate some phase data, in seconds.
>>> (taus, adevs, errors, ns) = allantools.oadev(x)

when only one input parameter is given, phase data in seconds is assumed when no rate parameter is given, rate=1.0 is the default when no taus parameter is given, taus=’octave’ is the default

### Frequency data example

Note that allantools assumes non-dimensional frequency data input. Normalization, by e.g. dividing all data points with the average frequency, is left to the user.

>>> import allantools
>>> import pylab as plt
>>> import numpy as np
>>> t = np.logspace(0, 3, 50)  # tau values from 1 to 1000
>>> y = allantools.noise.white(10000)  # Generate some frequency data
>>> r = 12.3  # sample rate in Hz of the input data
>>> fig = plt.loglog(t2, ad) # Plot the results
>>> # plt.show()

New in 2016.11 : simple top-level API, using dedicated classes for data handling and plotting.

import allantools # https://github.com/aewallin/allantools/
import numpy as np

# Compute a deviation using the Dataset class
a = allantools.Dataset(data=np.random.rand(1000))
a.compute("mdev")

# New in 2019.7 : write results to file
a.write_result("output.dat")

# Plot it using the Plot class
b = allantools.Plot()
# New in 2019.7 : additional keyword arguments are passed to
# matplotlib.pyplot.plot()
b.plot(a, errorbars=True, grid=True)
# You can override defaults before "show" if needed
b.ax.set_xlabel("Tau (s)")
b.show()

## Jupyter notebooks with examples

Jupyter notebooks are interactive python scripts, embedded in a browser, allowing you to manipulate data and display plots like easily. For guidance on installing jupyter, please refer to https://jupyter.org/install.

See /examples for some examples in notebook format.

github formats the notebooks into nice web-pages, for example

## Project details

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