clouddrift.signal.modulated_ellipse_signal#
- clouddrift.signal.modulated_ellipse_signal(kappa: ndarray | DataArray, lambda_: ndarray | DataArray, theta: ndarray | DataArray, phi: ndarray | DataArray) tuple[ndarray, ndarray][source]#
Return the analytic Cartesian signals (xa, ya) from the instantaneous parameters of a modulated elliptical signal.
This function is the inverse of
ellipse_parameters().Parameters#
- kappaarray_like
Ellipse root-mean-square amplitude.
- lambdaarray_like
Ellipse linearity between -1 and 1, or departure from circular motion (lambda=0).
- thetaarray_like
Ellipse orientation in radian.
- phiarray_like
Ellipse phase in radian.
- time_axisint, optional
The axis of the time array. Default is -1, which corresponds to the last axis.
Returns#
- xanp.ndarray
Complex-valued analytic signal for first Cartesian component (zonal, east-west).
- yanp.ndarray
Complex-valued analytic signal for second Cartesian component (meridional, north-south).
Examples#
To obtain the analytic signals from the instantaneous parameters of a modulated elliptical signal:
>>> xa, ya = modulated_ellipse_signal(kappa, lambda, theta, phi)
Raises#
- ValueError
If the input arrays do not have the same shape.
References#
Lilly JM, Olhede SC. 2010 Bivariate instantaneous frequency and bandwidth. IEEE T. Signal Proces. 58, 591–603. (10.1109/TSP.2009.2031729).
See Also#
ellipse_parameters(),analytic_signal(),rotary_to_cartesian(),cartesian_to_rotary()