`get_modes`#

acoular.sources.get_modes(lOrder, direction, mpos, sourceposition=None)

Calculate the spherical harmonic radiation pattern at microphone positions.

This function computes the spherical harmonic radiation pattern values at each microphone position for a given maximum spherical harmonic order (lOrder), orientation (direction), and optional source position (sourceposition).

Parameters:

lOrderint: The maximum order of spherical harmonics to compute. The resulting modes will include all orders up to and including lOrder.
directionnumpy.ndarray of shape (3,): Unit vector representing the orientation of the spherical harmonics. Should contain the x, y, and z components of the direction.
mposnumpy.ndarray of shape (3, N): Microphone positions in a 3D Cartesian coordinate system. The array should have 3 rows (the x, y and z coordinates) and N columns (one for each microphone).
sourcepositionnumpy.ndarray of shape (3,), optional: Position of the source in a 3D Cartesian coordinate system. If not provided, it defaults to the origin [0, 0, 0].

Returns:

numpy.ndarray of shape (N, (lOrder+1) ** 2): Complex values representing the spherical harmonic radiation pattern at each microphone position (N microphones) for each spherical harmonic mode.

See also

get_radiation_angles(): Computes azimuth and elevation angles between microphones and the source.
scipy.special.sph_harm: Computes spherical harmonic values.

Notes

The azimuth (azi) and elevation (ele) angles between the microphones and the source are calculated using the get_radiation_angles() function.
Spherical harmonics (sph_harm) are computed for each mode (l, m), where l is the degree (ranging from 0 to lOrder) and m is the order (ranging from -l to +l).
For negative orders (m < 0), the conjugate of the spherical harmonic is computed and scaled by the imaginary unit 1j.

Examples

>>> import acoular as ac
>>> import numpy as np
>>>
>>> lOrder = 2
>>> direction = [0, 0, 1]  # Orientation along z-axis
>>> mpos = np.array([[1, -1], [1, -1], [0, 0]])  # Two microphones
>>> sourcepos = [0, 0, 0]  # Source at origin
>>>
>>> modes = ac.sources.get_modes(lOrder, direction, mpos, sourcepos)
>>> modes.shape
(2, 9)

get_modes#

`get_modes`#