.. DO NOT EDIT.
.. THIS FILE WAS AUTOMATICALLY GENERATED BY SPHINX-GALLERY.
.. TO MAKE CHANGES, EDIT THE SOURCE PYTHON FILE:
.. "examples/spectrogram/spectrogram2.py"
.. LINE NUMBERS ARE GIVEN BELOW.

.. only:: html

    .. note::
        :class: sphx-glr-download-link-note

        :ref:`Go to the end <sphx_glr_download_examples_spectrogram_spectrogram2.py>`
        to download the full example code.

.. rst-class:: sphx-glr-example-title

.. _sphx_glr_examples_spectrogram_spectrogram2.py:


.. sectionauthor:: Duncan Macleod <duncan.macleod@ligo.org>
.. currentmodule:: gwpy.timeseries

Plotting an over-dense, short-duration `Spectrogram`
####################################################

The normal `~TimeSeries.spectrogram` method uses non-overlapping intervals
to calculate discrete PSDs for each stride. This is fine for long-duration
data, but give poor resolution when studying short-duration phenomena.

The `~TimeSeries.spectrogram2` method allows for highly-overlapping FFT
calculations to over-sample the frequency content of the input `TimeSeries`
to produce a much more feature-rich output.

.. GENERATED FROM PYTHON SOURCE LINES 36-38

To demonstrate this, we can download some data associated with the
gravitational-wave event GW510914:

.. GENERATED FROM PYTHON SOURCE LINES 38-42

.. code-block:: Python


    from gwpy.timeseries import TimeSeries
    lho = TimeSeries.fetch_open_data("H1", 1126259458, 1126259467)








.. GENERATED FROM PYTHON SOURCE LINES 43-46

and can :meth:`~TimeSeries.highpass` and :meth:`~TimeSeries.whiten`
the remove low-frequency noise and try and enhance low-amplitude signals
across the middle of the frequency band:

.. GENERATED FROM PYTHON SOURCE LINES 46-50

.. code-block:: Python


    hp = lho.highpass(20)
    white = hp.whiten(4, 2).crop(1126259460, 1126259465)








.. GENERATED FROM PYTHON SOURCE LINES 51-60

.. note::

   We chose to :meth:`~TimeSeries.crop` out the leading and trailing 2
   seconds of the the whitened data series here to remove any filtering
   artefacts that may have been introduced.

Now we can call the `~TimeSeries.spectrogram2` method of `gwdata` to
calculate our over-dense `~gwpy.spectrogram.Spectrogram`, using a
1/16-second FFT length and high overlap:

.. GENERATED FROM PYTHON SOURCE LINES 60-64

.. code-block:: Python


    specgram = white.spectrogram2(fftlength=1/16., overlap=15/256.) ** (1/2.)
    specgram = specgram.crop_frequencies(20)  # drop everything below highpass








.. GENERATED FROM PYTHON SOURCE LINES 65-66

Finally, we make a plot:

.. GENERATED FROM PYTHON SOURCE LINES 66-74

.. code-block:: Python


    plot = specgram.plot(norm="log", cmap="viridis", yscale="log")
    ax = plot.gca()
    ax.set_title("LIGO-Hanford strain data around GW150914")
    ax.set_xlim(1126259462, 1126259463)
    ax.colorbar(label=r"Strain ASD [1/$\sqrt{\mathrm{Hz}}$]")
    plot.show()




.. image-sg:: /examples/spectrogram/images/sphx_glr_spectrogram2_001.png
   :alt: LIGO-Hanford strain data around GW150914
   :srcset: /examples/spectrogram/images/sphx_glr_spectrogram2_001.png
   :class: sphx-glr-single-img





.. GENERATED FROM PYTHON SOURCE LINES 75-80

Here we can see the trace of a high-mass binary black hole system,
referred to as GW150914.
For more details on this signal, please see
`Abbott et al. (2016) <https://doi.org/10.1103/PhysRevLett.116.061102>`_
(the joint LSC-Virgo publication announcing this detection).


.. rst-class:: sphx-glr-timing

   **Total running time of the script:** (0 minutes 0.627 seconds)


.. _sphx_glr_download_examples_spectrogram_spectrogram2.py:

.. only:: html

  .. container:: sphx-glr-footer sphx-glr-footer-example

    .. container:: sphx-glr-download sphx-glr-download-jupyter

      :download:`Download Jupyter notebook: spectrogram2.ipynb <spectrogram2.ipynb>`

    .. container:: sphx-glr-download sphx-glr-download-python

      :download:`Download Python source code: spectrogram2.py <spectrogram2.py>`

    .. container:: sphx-glr-download sphx-glr-download-zip

      :download:`Download zipped: spectrogram2.zip <spectrogram2.zip>`


.. only:: html

 .. rst-class:: sphx-glr-signature

    `Gallery generated by Sphinx-Gallery <https://sphinx-gallery.github.io>`_