# step

**System object: **phased.TimeDelayLCMVBeamformer

**Package: **phased

Perform time-delay LCMV beamforming

## Syntax

`Y = step(H,X)`

Y = step(H,X,XT)

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.

`Y = step(H,X)`

performs time-delay LCMV
beamforming on the input, `X`

, and returns the
beamformed output in `Y`

. `X`

is
an *M*-by-*N* matrix where *N* is
the number of elements of the sensor array. *M* must
be larger than the FIR filter length specified in the `FilterLength`

property. `Y`

is
a column vector of length *M*.

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.

`Y = step(H,X,XT)`

uses `XT`

as
the training samples to calculate the beamforming weights when you
set the `TrainingInputPort`

property to `true`

. `XT`

is
an *M*-by-*N* matrix where *N* is
the number of elements of the sensor array. *M* must
be larger than the FIR filter length specified in the `FilterLength`

property.

`Y = step(H,X,ANG)`

uses `ANG`

as
the beamforming direction, when you set the `DirectionSource`

property
to `'Input port'`

. `ANG`

is a
column vector of length 2 in the form of `[AzimuthAngle; ElevationAngle]`

(in
degrees). The azimuth angle must be between –180° and
180°, and the elevation angle must be between –90°
and 90°.

You can combine optional input arguments when their enabling
properties are set: `Y = step(H,X,XT,ANG)`

`[Y,W] = step(___)`

returns additional
output, `W`

, as the beamforming weights when you
set the `WeightsOutputPort`

property to `true`

. `W`

is
a column vector of length *L*, where *L* is
the number of degrees of freedom of the beamformer. For a time-delay
LCMV beamformer, the number of degrees of freedom is given by the
product of the number of elements of the array and the filter length
specified by the value of the `FilterLength`

property.

**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.

All input and output arguments can be single or double precision.

## Examples

## Algorithms

The beamforming algorithm is the time-domain counterpart of the narrowband linear constraint minimum variance (LCMV) beamformer. The algorithm does the following:

Steers the array to the beamforming direction.

Applies an FIR filter to the output of each sensor to achieve the specified constraints. The filter is specific to each sensor.