Allan deviation and related time/frequency statistics
Project description
A python library for calculating Allan deviation and related time & frequency statistics. LGPL v3+ license.
- Development at https://github.com/aewallin/allantools
- Installation package at https://pypi.python.org/pypi/AllanTools
- Discussion group at https://groups.google.com/d/forum/allantools
- Documentation available at https://allantools.readthedocs.org
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 |
|---|---|
| adev() | Allan deviation |
| oadev() | Overlapping Allan deviation |
| mdev() | Modified Allan deviation |
| tdev() | Time deviation |
| hdev() | Hadamard deviation |
| ohdev() | Overlapping Hadamard deviation |
| totdev() | Total deviation |
| mtotdev() | Modified total deviation |
| ttotdev() | Time total deviation |
| htotdev() | Hadamard total deviation |
| theo1() | Theo1 deviation |
| mtie() | Maximum Time Interval Error |
| tierms() | Time Interval Error RMS |
| gradev() | 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 >>> (t2, ad, ade, adn) = allantools.oadev(y, rate=r, data_type="freq", taus=t) # Compute the overlapping ADEV >>> 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
Release history Release notifications | RSS feed
Download files
Download the file for your platform. If you're not sure which to choose, learn more about installing packages.