BeamformerBase¶

class
acoular.fbeamform.
BeamformerBase
¶ Bases:
traits.has_traits.HasPrivateTraits
Beamforming using the basic delayandsum algorithm in the frequency domain.

steer
= Property(desc="steering vector object")¶ SteeringVector
or derived object. Defaults toSteeringVector
object.

freq_data
= Trait(PowerSpectra, …¶ PowerSpectra
object that provides the cross spectral matrix and eigenvalues

r_diag
= Bool(True, …¶ Boolean flag, if ‘True’ (default), the main diagonal is removed before beamforming.

r_diag_norm
= Float(0.0, …¶ If r_diag==True: if r_diag_norm==0.0, the standard normalization = num_mics/(num_mics1) is used. If r_diag_norm !=0.0, the user input is used instead. If r_diag==False, the normalization is 1.0 either way.

precision
= Trait('float64', 'float32', …¶ Floating point precision of property result. Corresponding to numpy dtypes. Default = 64 Bit.

cached
= Bool(True, …¶ Boolean flag, if ‘True’ (default), the result is cached in h5 files.

result
= Property( …¶ The beamforming result as squared sound pressure values at all grid point locations (readonly). Returns a (number of frequencies, number of gridpoints) array of floats.

sig_loss_norm
()¶ If the diagonal of the CSM is removed one has to handle the loss of signal energy –> Done via a normalization factor.

calc
(ac, fr)¶ Calculates the delayandsum beamforming result for the frequencies defined by
freq_data
This is an internal helper function that is automatically called when accessing the beamformer’s
result
or calling itssynthetic()
method. Parameters
 acarray of floats
This array of dimension ([number of frequencies]x[number of gridpoints]) is used as callbyreference parameter and contains the calculated value after calling this method.
 frarray of booleans
The entries of this [number of frequencies]sized array are either ‘True’ (if the result for this frequency has already been calculated) or ‘False’ (for the frequencies where the result has yet to be calculated). After the calculation at a certain frequency the value will be set to ‘True’
 Returns
 This method only returns values through the ac and fr parameters

synthetic
(f, num=0)¶ Evaluates the beamforming result for an arbitrary frequency band.
 Parameters
 f: float
Band center frequency.
 numinteger
Controls the width of the frequency bands considered; defaults to 0 (single frequency line).
num
frequency band width
0
single frequency line
1
octave band
3
thirdoctave band
n
1/noctave band
 Returns
 array of floats
The synthesized frequency band values of the beamforming result at each grid point . Note that the frequency resolution and therefore the bandwidth represented by a single frequency line depends on the
sampling frequency
and usedFFT block size
.

integrate
(sector)¶ Integrates result map over a given sector.
 Parameters
 sector: array of floats
Tuple with arguments for the ‘indices’ method of a
Grid
derived class (e.g.RectGrid.indices
orRectGrid3D.indices
). Possible sectors would be array([xmin, ymin, xmax, ymax]) or array([x, y, radius]).
 Returns
 array of floats
The spectrum (all calculated frequency bands) for the integrated sector.
