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

    Click :ref:`here <sphx_glr_download_auto_examples_plot_4_3_2_reassigned_spectrogram.py>` to download the full example code
.. rst-class:: sphx-glr-example-title

.. _sphx_glr_auto_examples_plot_4_3_2_reassigned_spectrogram.py:


========================================================
Comparison of a Spectrogram and a Reassigned Spectrogram
========================================================

This example compares the spectrogram and the reassigned spectrogram of a
hybrid signal (containing sinusoidal, constant and linear frequency
modulations), against its ideal time-frequency characteristics.

Figure 4.34 from the tutorial.



.. image:: /auto_examples/images/sphx_glr_plot_4_3_2_reassigned_spectrogram_001.png
    :class: sphx-glr-single-img


.. rst-class:: sphx-glr-script-out

 Out:

 .. code-block:: none

    /home/docs/checkouts/readthedocs.org/user_builds/tftb/envs/latest/lib/python3.7/site-packages/tftb/processing/reassigned.py:542: ComplexWarning: Casting complex values to real discards the imaginary part
      rtfr[int(jcolhat), int(icolhat) - 1] += tfr[jcol, icol]
    /home/docs/checkouts/readthedocs.org/user_builds/tftb/envs/latest/lib/python3.7/site-packages/numpy/ma/core.py:2786: ComplexWarning: Casting complex values to real discards the imaginary part
      order=order, subok=True, ndmin=ndmin)





|


.. code-block:: default


    from tftb.generators import fmsin, fmhyp
    from tftb.processing import ideal_tfr, reassigned_spectrogram, Spectrogram
    import numpy as np
    import matplotlib.pyplot as plt

    n_points = 128
    sig1, if1 = fmsin(n_points, 0.15, 0.45, 100, 1, 0.4, -1)
    sig2, if2 = fmhyp(n_points, [1, .5], [32, 0.05])
    sig = sig1 + sig2
    ideal, t, f = ideal_tfr(np.vstack((if1, if2)))
    _, re_spec, _ = reassigned_spectrogram(sig)
    spec, t3, f3 = Spectrogram(sig).run()

    # Ideal tfr
    plt.subplot(221)
    plt.contour(t, f, ideal, 1)
    plt.grid(True)
    plt.gca().set_xticklabels([])
    plt.title("Ideal time-frequency distro")
    plt.ylabel('Normalized Frequency')

    # Spectrogram
    plt.subplot(222)
    plt.contour(t3, f3[:64], spec[:64, :])
    plt.grid(True)
    plt.gca().set_xticklabels([])
    plt.title("Spectrogram")

    # Reassigned Spectrogram
    plt.subplot(212)
    f = np.linspace(0, 0.5, 64)
    plt.contour(np.arange(128), f, re_spec[:64, :])
    plt.grid(True)
    plt.title("Reassigned Spectrogram")
    plt.xlabel('Time')
    plt.ylabel('Normalized Frequency')

    plt.show()


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

   **Total running time of the script:** ( 0 minutes  2.149 seconds)


.. _sphx_glr_download_auto_examples_plot_4_3_2_reassigned_spectrogram.py:


.. only :: html

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



  .. container:: sphx-glr-download

     :download:`Download Python source code: plot_4_3_2_reassigned_spectrogram.py <plot_4_3_2_reassigned_spectrogram.py>`



  .. container:: sphx-glr-download

     :download:`Download Jupyter notebook: plot_4_3_2_reassigned_spectrogram.ipynb <plot_4_3_2_reassigned_spectrogram.ipynb>`


.. only:: html

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

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