scipy.signal.sweep_poly¶
- scipy.signal.sweep_poly(t, poly, phi=0)[source]¶
Frequency-swept cosine generator, with a time-dependent frequency.
This function generates a sinusoidal function whose instantaneous frequency varies with time. The frequency at time t is given by the polynomial poly.
Parameters : t : ndarray
Times at which to evaluate the waveform.
poly : 1-D array-like or instance of numpy.poly1d
The desired frequency expressed as a polynomial. If poly is a list or ndarray of length n, then the elements of poly are the coefficients of the polynomial, and the instantaneous frequency is
f(t) = poly[0]*t**(n-1) + poly[1]*t**(n-2) + ... + poly[n-1]
If poly is an instance of numpy.poly1d, then the instantaneous frequency is
f(t) = poly(t)
phi : float, optional
Phase offset, in degrees, Default: 0.
Returns : sweep_poly : ndarray
A numpy array containing the signal evaluated at t with the requested time-varying frequency. More precisely, the function returns cos(phase + (pi/180)*phi), where phase is the integral (from 0 to t) of 2 * pi * f(t); f(t) is defined above.
See also
Notes
New in version 0.8.0.
If poly is a list or ndarray of length n, then the elements of poly are the coefficients of the polynomial, and the instantaneous frequency is:
f(t) = poly[0]*t**(n-1) + poly[1]*t**(n-2) + ... + poly[n-1]If poly is an instance of numpy.poly1d, then the instantaneous frequency is:
f(t) = poly(t)Finally, the output s is:
cos(phase + (pi/180)*phi)where phase is the integral from 0 to t of 2 * pi * f(t), f(t) as defined above.