'Plot the angle spectrum.
Call signature::
angle_spectrum(x, Fs=2, Fc=0,  window=mlab.window_hanning,
pad_to=None, sides=\'default\', **kwargs)
Compute the angle spectrum (wrapped phase spectrum) of *x*.
Data is padded to a length of *pad_to* and the windowing function
*window* is applied to the signal.
Parameters
x : 1-D array or sequence
Array or sequence containing the data
%(Spectral)s
%(Single_Spectrum)s
Fc : integer
The center frequency of *x* (defaults to 0), which offsets
the x extents of the plot to reflect the frequency range used
when a signal is acquired and then filtered and downsampled to
baseband.
Returns
spectrum : 1-D array
The values for the angle spectrum in radians (real valued)
freqs : 1-D array
The frequencies corresponding to the elements in *spectrum*
line : a :class:`~matplotlib.lines.Line2D` instance
The line created by this function
Other Parameters
**kwargs :
Keyword arguments control the :class:`~matplotlib.lines.Line2D`
properties:
%(Line2D)s
See Also
:func:`magnitude_spectrum`
:func:`angle_spectrum` plots the magnitudes of the corresponding
frequencies.
:func:`phase_spectrum`
:func:`phase_spectrum` plots the unwrapped version of this
function.
:func:`specgram`
:func:`specgram` can plot the angle spectrum of segments within the
signal in a colormap.'

@_preprocess_data(replace_names=[u'x'], label_namer=None)
@docstring.dedent_interpd
def angle_spectrum(self, x, Fs=None, Fc=None, window=None, pad_to=None, sides=None, **kwargs):

    if (not self._hold):
        self.cla()
    if (Fc is None):
        Fc = 0
    (spec, freqs) = mlab.angle_spectrum(x=x, Fs=Fs, window=window, pad_to=pad_to, sides=sides)
    freqs += Fc
    lines = self.plot(freqs, spec, **kwargs)
    self.set_xlabel(u'Frequency')
    self.set_ylabel(u'Angle    (radians)')
    return (spec, freqs, lines[0])
