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# Rewrote much of chirp()
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from numpy import asarray, zeros, place, nan, mod, pi, extract, log, sqrt, \
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exp, cos, sin, polyval, polyint, size, log10
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exp, cos, sin, polyval, polyint
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def sawtooth(t,width=1):
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def sawtooth(t, width=1):
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Return a periodic sawtooth waveform.
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place(y,mask3,-1)
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def gausspulse(t,fc=1000,bw=0.5,bwr=-6,tpr=-60,retquad=0,retenv=0):
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def gausspulse(t, fc=1000, bw=0.5, bwr=-6, tpr=-60, retquad=False, retenv=False):
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Return a gaussian modulated sinusoid: exp(-a t^2) exp(1j*2*pi*fc).
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Return a gaussian modulated sinusoid: exp(-a t^2) exp(1j*2*pi*fc*t).
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If `retquad` is non-zero, then return the real and imaginary parts
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(in-phase and quadrature)
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If `retenv` is non-zero, then return the envelope (unmodulated signal).
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If `retquad` is True, then return the real and imaginary parts
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(in-phase and quadrature).
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If `retenv` is True, then return the envelope (unmodulated signal).
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Otherwise, return the real part of the modulated sinusoid.
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t : ndarray, or the string 'cutoff'
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fc : int, optional
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Center frequency (Hz).
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Center frequency (Hz). Default is 1000.
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bw : float, optional
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Fractional bandwidth in frequency domain of pulse (Hz).
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bwr: float, optional
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Reference level at which fractional bandwidth is calculated (dB).
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tpr : float, optional
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If `t` is 'cutoff', then the function returns the cutoff
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time for when the pulse amplitude falls below `tpr` (in dB).
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retquad : int, optional
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Return the quadrature (imaginary) as well as the real part
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retenv : int, optional
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Return the envelope of the signal.
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retquad : bool, optional
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If True, return the quadrature (imaginary) as well as the real part
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of the signal. Default is False.
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retenv : bool, optional
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If True, return the envelope of the signal. Default is False.
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raise ValueError, "Center frequency (fc=%.2f) must be >=0." % fc
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raise ValueError("Center frequency (fc=%.2f) must be >=0." % fc)
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raise ValueError, "Fractional bandwidth (bw=%.2f) must be > 0." % bw
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raise ValueError("Fractional bandwidth (bw=%.2f) must be > 0." % bw)
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raise ValueError, "Reference level for bandwidth (bwr=%.2f) must " \
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raise ValueError("Reference level for bandwidth (bwr=%.2f) must "
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# exp(-a t^2) <-> sqrt(pi/a) exp(-pi^2/a * f^2) = g(f)
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return yI, yQ, yenv
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# This is chirp from scipy 0.7:
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def old_chirp(t, f0=0, t1=1, f1=100, method='linear', phi=0, qshape=None):
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"""Frequency-swept cosine generator.
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Times at which to evaluate the waveform.
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f0 : float or ndarray, optional
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Frequency (in Hz) of the waveform at time 0. If `f0` is an
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ndarray, it specifies the frequency change as a polynomial in
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`t` (see Notes below).
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Time at which `f1` is specified.
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Frequency (in Hz) of the waveform at time `t1`.
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method : {'linear', 'quadratic', 'logarithmic'}, optional
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Kind of frequency sweep.
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Phase offset, in degrees.
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qshape : {'convex', 'concave'}
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If method is 'quadratic', `qshape` specifies its shape.
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If `f0` is an array, it forms the coefficients of a polynomial in
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`t` (see `numpy.polval`). The polynomial determines the waveform
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frequency change in time. In this case, the values of `f1`, `t1`,
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`method`, and `qshape` are ignored.
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This function is deprecated. It will be removed in SciPy version 0.9.0.
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It exists so that during in version 0.8.0, the new chirp function can
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call this function to preserve the old behavior of the quadratic chirp.
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warnings.warn("The function old_chirp is deprecated, and will be removed in "
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"SciPy 0.9", DeprecationWarning)
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# Convert to radians.
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# We were given a polynomial.
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return cos(2*pi*polyval(polyint(f0),t)+phi)
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if method in ['linear','lin','li']:
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phase_angle = 2*pi * (f0*t + 0.5*beta*t*t)
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elif method in ['quadratic','quad','q']:
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if qshape == 'concave':
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elif qshape == 'convex':
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raise ValueError("qshape must be either 'concave' or 'convex' but "
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"a value of %r was given." % qshape)
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phase_angle = 2*pi * (f0*t + beta*t*t*t/3)
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elif method in ['logarithmic','log','lo']:
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"For a logarithmic sweep, f1=%f must be larger than f0=%f."
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beta = log10(f1-f0)/t1
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phase_angle = 2*pi * (f0*t + (pow(10,beta*t)-1)/(beta*log(10)))
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raise ValueError("method must be 'linear', 'quadratic', or "
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"'logarithmic' but a value of %r was given." % method)
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return cos(phase_angle + phi)
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def chirp(t, f0, t1, f1, method='linear', phi=0, vertex_zero=True,
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def chirp(t, f0, t1, f1, method='linear', phi=0, vertex_zero=True):
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"""Frequency-swept cosine generator.
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In the following, 'Hz' should be interpreted as 'cycles per time unit';
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f1 must be positive, and f0 must be greater than f1.
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# Preserve old behavior for one release cycle; this can be
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# removed in scipy 0.9.
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warnings.warn("Passing a list of polynomial coefficients in f0 to the "
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"function chirp is deprecated. Use scipy.signal.sweep_poly.",
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return old_chirp(t, f0, t1, f1, method, phi, qshape)
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if method in ['quadratic', 'quad', 'q'] and qshape is not None:
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# We must use the old version of the quadratic chirp. Fortunately,
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# the old API *required* that qshape be either 'convex' or 'concave'
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# if the quadratic method was selected--`None` would raise an error.
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# So if the code reaches this point, we should use the old version.
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warnings.warn("The qshape keyword argument is deprecated. "
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"Use vertex_zero.", DeprecationWarning)
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waveform = old_chirp(t, f0, t1, f1, method, phi, qshape)
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# 'phase' is computed in _chirp_phase, to make testing easier.
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phase = _chirp_phase(t, f0, t1, f1, method, vertex_zero)
added
removed
scipy/signal/waveforms.py
