Plot Utilities

Customized functions for plotting and vizualization (optic.plot)

pconst(x[, lim, R, pType, cmap, whiteb])

Plot signal constellations.

constHist(symb, ax[, cmap, whiteb])

Generate histogram-based constellation plot.

plotColoredConst(symb, constSymb[, px, SNR, ...])

Colored constellation scatter plot.

plotDecisionBoundaries(constSymb[, px, SNR, ...])

Plot decision boundaries for a given constellation symbols.

eyediagram(sigIn, Nsamples, SpS[, n, ptype, ...])

Plot the eye diagram of a modulated signal waveform.

plotPSD(sig[, Fs, Fc, NFFT, fig, label])

Plot the power spectrum density (PSD) of a signal.

randomCmap([nColors, low, high])

Generate a random colormap with the specified number of colors and random RGB values.
animateConstGIF(x, figName, xlabel='In-Phase (I)', ylabel='Quadrature (Q)', title=[], color='b', centralAxes=False, squareAxes=True, fram=200, inter=20, radius=2)

Create and save a constellation plot animation as GIF

Parameters:

  • x (numpy.ndarray) – x-axis values.

  • figName (str) – Figure file name with folder path.

  • xlabel (str, optional) – X-axis label. Default is ‘In-Phase (I)’.

  • ylabel (str, optional) – Y-axis label. Default is ‘Quadrature (Q)’.

  • title (str, optional) – Title of the plot.

  • color (str, optional) – Color of the points in the plot. Default is ‘b’ (blue).

  • centralAxes (bool, optional) – Whether to place the axes at the center. Default is False.

  • squareAxes (bool, optional) – Whether to keep the axes square. Default is True.

  • fram (int, optional) – Number of frames. Default is 200.

  • inter (int, optional) – Time interval between frames in milliseconds. Default is 20.

  • radius (int, optional) – Radius for setting plot limits. Default is 2.

constHist(symb, ax, cmap='turbo', whiteb=True)

Generate histogram-based constellation plot.

Parameters:

  • symb (np.array) – Complex-valued constellation symbols.

  • ax (axis object handle) – axis of the plot.

Returns:

ax – axis of the plot.

Return type:

axis object handle

eyediagram(sigIn, Nsamples, SpS, n=3, ptype='fast', plotlabel=None)

Plot the eye diagram of a modulated signal waveform.

Parameters:

  • sigIn (array-like) – Input signal waveform.

  • Nsamples (int) – Number of samples to be plotted.

  • SpS (int) – Samples per symbol.

  • n (int, optional) – Number of symbol periods. Defaults to 3.

  • ptype (str, optional) – Type of eye diagram. Can be ‘fast’ or ‘fancy’. Defaults to ‘fast’.

  • plotlabel (str, optional) – Label for the plot legend. Defaults to None.

Return type:

None

pconst(x, lim=True, R=1.25, pType='fancy', cmap='turbo', whiteb=True)

Plot signal constellations.

Parameters:

  • x (complex signals or list of complex signals) – Input signals.

  • lim (bool, optional) – Flag indicating whether to limit the axes to the radius of the signal. Defaults to True.

  • R (float, optional) – Scaling factor for the radius of the signal. Defaults to 1.25.

  • pType (str, optional) – Type of plot. “fancy” for scatter_density plot, “fast” for fast plot. Defaults to “fancy”.

  • cmap (str, optional) – Color map for scatter_density plot. Defaults to “turbo”.

  • whiteb (bool, optional) – Flag indicating whether to use white background for scatter_density plot. Defaults to True.

Returns:

  • fig (Figure) – Figure object.

  • ax (Axes or array of Axes) – Axes object(s).

plotColoredConst(symb, constSymb, px=None, SNR=20, rule='MAP', cmap=<matplotlib.colors.ListedColormap object>, fig=None, ax=None)

Colored constellation scatter plot.

Parameters:

  • symb (np.array) – Complex-valued constellation symbols.

  • constSymb (np.array) – Complex-valued constellation symbols used for detection.

  • px (array_like, optional) – Prior probabilities of symbols.

  • SNR (float, optional) – Signal-to-Noise Ratio (SNR) in decibels (dB). Default is 20 dB.

  • rule (str, optional) – Detection rule, either “MAP” for Maximum A Posteriori or “ML” for Maximum Likelihood. Default is “MAP”.

  • cmap (matplotlib.colors.Colormap, optional) – Colormap for coloring the constellation symbols. Default is matplotlib.cm.turbo.

  • fig (matplotlib.figure.Figure, optional) – Figure object for the plot. If None, a new figure is created. Default is None.

  • ax (matplotlib.axes.Axes, optional) – Axes object for the plot. If None, a new axes is created. Default is None.

Returns:

  • fig (matplotlib.figure.Figure) – Figure object for the plot.

  • ax (matplotlib.axes.Axes) – Axes object for the plot.

Notes

This function generates a scatter plot of complex-valued constellation symbols with colors representing the corresponding decided constellation symbols based on detection results.

The detected symbols are determined using a detector based on the provided input symbols, noise variance, detection rule, and prior probabilities (if available).

plotDecisionBoundaries(constSymb, px=None, SNR=20, rule='MAP', gridStep=0.001, d=0.5, cmap=<matplotlib.colors.ListedColormap object>, fig=None, ax=None)

Plot decision boundaries for a given constellation symbols.

Parameters:

  • constSymb (array_like) – An array of complex constellation symbols.

  • px (array_like, optional) – Prior probabilities for each symbol in constSymb. If None, equal probabilities are assumed.

  • SNR (float, optional) – Signal-to-noise ratio in decibels (dB). Default is 20.

  • rule (str, optional) – The detection rule to use. Either ‘MAP’ (default) or ‘ML’.

  • gridStep (float, optional) – Step size for creating the decision boundary grid. Default is 0.001.

  • d (float, optional) – Margin added to the maximum and minimum values of real and imaginary parts of constSymb. Default is 0.5.

  • cmap (str or Colormap, optional) – Colormap to be used for the contour plot. Default is ‘turbo’.

  • fig (matplotlib.figure.Figure, optional) – Figure object for the plot. If None, a new figure is created. Default is None.

  • ax (matplotlib.axes.Axes, optional) – Axes object for the plot. If None, a new axes is created. Default is None.

Returns:

  • fig (matplotlib.figure.Figure) – The created matplotlib figure.

  • ax (matplotlib.axes.Axes) – The created matplotlib axes.

Notes

This function plots decision boundaries for a given set of constellation symbols in the complex plane. It uses the specified signal-to-noise ratio (SNR), detection rule, and prior probabilities (if available) to determine the decision boundaries.

The decision boundaries are plotted using a contour plot with colors representing the different decision regions.

plotPSD(sig, Fs=1, Fc=0, NFFT=4096, fig=None, label=None)

Plot the power spectrum density (PSD) of a signal.

Parameters:

  • sig (np.array) – input signal.

  • Fs (scalar, optional) – signal’s sampling frequency. The default is 1.

  • Fc (scalar, optional) – signal’s central frequency. The default is 0.

  • NFFT (scalar int, optional) – FFT size. The default is 4096.

  • fig (figure object, optional) – matplotlib figure handle. The default is [].

  • label (string, optional) – PSD plot label. The default is [].

Returns:

  • fig (matplotlib figure object) – matplotlib figure object where the plot is generated.

  • matplotlib axes object – matplotlib axes object where the plot is displayed.

randomCmap(nColors=100, low=0.1, high=0.99)

Generate a random colormap with the specified number of colors and random RGB values.

Parameters:

  • nColors (int, optional) – Number of colors in the colormap. Defaults to 100.

  • low (float, optional) – Lower bound for random RGB values. Defaults to 0.1.

  • high (float, optional) – Upper bound for random RGB values. Defaults to 0.99.

Returns:

Random colormap with the specified number of colors and random RGB values.

Return type:

matplotlib.colors.ListedColormap