Time delay LCMV beamformer
The TimeDelayLCMVBeamformer
object implements
a timedelay linear constraint minimum variance beamformer.
To compute the beamformed signal:
Define and set up your timedelay LCMV beamformer. See Construction.
Call step
to
perform the beamforming operation according to the properties of phased.TimeDelayLCMVBeamformer
.
The behavior of step
is specific to each object in
the toolbox.
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.
H = phased.TimeDelayLCMVBeamformer
creates
a timedelay linear constraint minimum variance (LCMV) beamformer System
object, H
.
The object performs time delay LCMV beamforming on the received signal.
H = phased.TimeDelayLCMVBeamformer(
creates
a timedelay LCMV beamformer object, Name
,Value
)H
, with
each specified property Name set to the specified Value. You can specify
additional namevalue pair arguments in any order as (Name1
,Value1
,...,NameN
,ValueN
).

Handle to sensor array Specify the sensor array as a handle. The sensor array must
be an array object in the Default:  

Signal propagation speed Specify the propagation speed of the signal, in meters per second, as a positive scalar. Default: Speed of light  

Signal sampling rate Specify the signal sampling rate (in hertz) as a positive scalar. Default:  

FIR filter length Specify the length of the FIR filter behind each sensor element in the array as a positive integer. Default:  

Constraint matrix Specify the constraint matrix used for timedelay LCMV beamformer
as an MbyK matrix. Each column
of the matrix is a constraint and M is the number
of degrees of freedom of the beamformer. For a timedelay 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 Default:  

Desired response vector Specify the desired response used for timedelay LCMV beamformer
as a column vector of length K, where K is
the number of constraints in the Default:  

Diagonal loading factor Specify the diagonal loading factor as a positive scalar. Diagonal loading is a technique used to achieve robust beamforming performance, especially when the sample support is small. This property is tunable. Default:  

Add input to specify training data To specify additional training data, set this property to Default:  

Source of beamforming direction Specify whether the beamforming direction comes from the
Default:  

Beamforming direction Specify the beamforming direction of the beamformer as a column
vector of length 2. The direction is specified in the format of Default:  

Output beamforming weights To obtain the weights used in the beamformer, set this property
to Default: 
step  Perform timedelay LCMV beamforming 
Common to All System Objects  

clone  Create System object with same property values 
getNumInputs  Expected number of inputs to a System object 
getNumOutputs  Expected number of outputs of a System object 
isLocked  Check locked states of a System object (logical) 
release  Allow System object property value changes 
The beamforming algorithm is the timedomain 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.
[1] Frost, O. “An Algorithm For Linearly Constrained Adaptive Array Processing”, Proceedings of the IEEE. Vol. 60, Number 8, August, 1972, pp. 926–935.
[2] Van Trees, H. Optimum Array Processing. New York: WileyInterscience, 2002.
phased.FrostBeamformer
 phased.PhaseShiftBeamformer
 phased.SubbandPhaseShiftBeamformer
 phased.TimeDelayBeamformer
 phitheta2azel
 uv2azel