phased.BeamscanEstimator2D System object

Package: phased

2-D beamscan spatial spectrum estimator

Description

The BeamscanEstimator2D object calculates a 2-D beamscan spatial spectrum estimate.

To estimate the spatial spectrum:

  1. Define and set up your 2-D beamscan spatial spectrum estimator. See Construction.

  2. Call step to estimate the spatial spectrum according to the properties of phased.BeamscanEstimator2D. The behavior of step is specific to each object in the toolbox.

Construction

H = phased.BeamscanEstimator2D creates a 2-D beamscan spatial spectrum estimator System object™, H. The object estimates the signal's spatial spectrum using a narrowband conventional beamformer.

H = phased.BeamscanEstimator2D(Name,Value) creates object, H, with each specified property Name set to the specified Value. You can specify additional name-value pair arguments in any order as (Name1,Value1,...,NameN,ValueN).

Properties

SensorArray

Handle to sensor array

Specify the sensor array as a handle. The sensor array must be an array object in the phased package. The array cannot contain subarrays.

Default: phased.ULA with default property values

PropagationSpeed

Signal propagation speed

Specify the propagation speed of the signal, in meters per second, as a positive scalar.

Default: Speed of light

OperatingFrequency

System operating frequency

Specify the operating frequency of the system in hertz as a positive scalar. The default value corresponds to 300 MHz.

Default: 3e8

ForwardBackwardAveraging

Perform forward-backward averaging

Set this property to true to use forward-backward averaging to estimate the covariance matrix for sensor arrays with conjugate symmetric array manifold.

Default: false

AzimuthScanAngles

Azimuth scan angles

Specify the azimuth scan angles (in degrees) as a real vector. The angles must be between –180 and 180, inclusive. You must specify the angles in ascending order.

Default: -90:90

ElevationScanAngles

Elevation scan angles

Specify the elevation scan angles (in degrees) as a real vector or scalar. The angles must be within [–90 90]. You must specify the angles in an ascending order.

Default: 0

DOAOutputPort

Enable DOA output

To obtain the signal's direction of arrival (DOA), set this property to true and use the corresponding output argument when invoking step. If you do not want to obtain the DOA, set this property to false.

Default: false

NumSignals

Number of signals

Specify the number of signals for DOA estimation as a positive scalar integer. This property applies when you set the DOAOutputPort property to true.

Default: 1

Methods

cloneCreate 2-D beamscan spatial spectrum estimator object with same property values
getNumInputsNumber of expected inputs to step method
getNumOutputsNumber of outputs from step method
isLockedLocked status for input attributes and nontunable properties
plotSpectrumPlot spatial spectrum
releaseAllow property value and input characteristics changes
resetReset states of 2-D beamscan spatial spectrum estimator object
stepPerform spatial spectrum estimation

Estimate the DOAs of Two Signals

Create the signals and solve for the DOA's

Estimate the DOAs of two signals received by a 50-element URA with a rectangular lattice. The antenna operating frequency is 150 MHz. The actual direction of the first signal is -37 degrees in azimuth and 0 degrees in elevation. The direction of the second signal is 17 degrees in azimuth and 20 degrees in elevation.

ha = phased.URA('Size',[5 10],'ElementSpacing',[1 0.6]);
ha.Element.FrequencyRange = [100e6 300e6];
fc = 150e6;
lambda = physconst('LightSpeed')/fc;
ang1 = [-37; 0]; ang2 = [17; 20];
x = sensorsig(getElementPosition(ha)/lambda,8000,[ang1 ang2],0.2);
hdoa = phased.BeamscanEstimator2D('SensorArray',ha,...
    'OperatingFrequency',fc,...
    'DOAOutputPort',true,'NumSignals',2,...
    'AzimuthScanAngles',-50:50,...
    'ElevationScanAngles',-30:30);
[~,doas] = step(hdoa,x)
doas =

   -37    17
     0    20

Plot the beamscan spatial spectrum

plotSpectrum(hdoa);

References

[1] Van Trees, H. Optimum Array Processing. New York: Wiley-Interscience, 2002.

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