step
System object: phased.PhaseShiftBeamformer
Namespace: phased
Perform phase shift beamforming
Syntax
Y = step(H,X)
Y = step(H,X,ANG)
[Y,W] =
step(___)
Description
Note
Starting in R2016b, instead of using the step
method
to perform the operation defined by the System object™, you can
call the object with arguments, as if it were a function. For example, y
= step(obj,x)
and y = obj(x)
perform
equivalent operations.
performs
phase shift beamforming on the input, Y
= step(H
,X
)X
, and
returns the beamformed output in Y
.
uses Y
= step(H
,X
,ANG
)ANG
as
the beamforming direction. This syntax is available when you set the DirectionSource
property
to 'Input port'
.
[
returns the beamforming weights, Y
,W
] =
step(___)W
.
This syntax is available when you set the WeightsOutputPort
property
to true
.
Note
The object performs an initialization the first time the object is executed. This
initialization locks nontunable properties
and input specifications, such as dimensions, complexity, and data type of the input data.
If you change a nontunable property or an input specification, the System object issues an error. To change nontunable properties or inputs, you must first
call the release
method to unlock the object.
Input Arguments
|
Beamformer object. |
|
Input signal, specified as an M-by-N matrix. If the sensor array contains subarrays, N is the number of subarrays; otherwise, N is the number of elements. The size of the first dimension of the input matrix can vary to simulate a changing signal length. A size change can occur, for example, in the case of a pulse waveform with variable pulse repetition frequency. |
|
Beamforming directions, specified as a two-row matrix. Each column has the form [AzimuthAngle; ElevationAngle], in degrees. Each azimuth angle must be between –180 and 180 degrees, and each elevation angle must be between –90 and 90 degrees. |
Output Arguments
|
Beamformed output. |
|
Beamforming weights. |
Examples
Algorithms
The phase shift beamformer uses the conventional delay-and-sum beamforming algorithm. The beamformer assumes the signal is narrowband, so a phase shift can approximate the required delay. The beamformer preserves the incoming signal power.
For further details, see [1].
References
[1] Van Trees, H. Optimum Array Processing. New York: Wiley-Interscience, 2002.