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phased.ATIScope

View angle-time array response

Description

The phased.ATIScope System object™ creates an angle-time intensity (ATI) scope for displaying array response intensities as a function of time and angle of arrival. You can input two types of data – in-phase/quadrature (I/Q) data or intensity data. In either case, the scope displays signal magnitude or signal power.

  • I/Q data – The data consists of fast-time I/Q samples of pulses and sweeps from multiple sensors. The scope creates intensity data and displays the array response map. To use I/Q data, set the IQDataInput property to true. In this mode, you can set the properties shown in Properties Applicable for Processed I/Q Data.

  • Intensity data – The data consists of angle-time array intensity data. The scope displays the angle-time intensity response map. For example, you can obtain time-angle intensity data from the output of a beamformer. To use intensity data, set the IQDataInput property to false. In this mode, you can set the properties shown in Properties Applicable for Viewing Response Data.

To display angle-time response data:

  1. Create the phased.ATIScope object and set its properties.

  2. Call the object with arguments, as if it were a function.

To learn more about how System objects work, see What Are System Objects?

Creation

Description

scope = phased.ATIScope() creates an ATI System object for displaying the angle-time intensity response of an array.

example

scope = phased.ATIScope(Name = Value) creates an ATI scope System object with each specified property set to the specified value. You can specify additional name-value pair arguments in any order as (Name1 = Value1, … ,NameN = ValueN). For example,

scope = phased.ATIScope(IQDataInput = true,IntensityUnits = "power", ...
        SensorArray = phased.URA(Size=[4,3]), OperatingFrequency = 1e6)
creates an ATI scope System object that process I/Q data from a 4-by-3 uniform rectangular array. The intensity is displayed in power units. The operating frequency is 1 MHz.

Properties

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Unless otherwise indicated, properties are nontunable, which means you cannot change their values after calling the object. Objects lock when you call them, and the release function unlocks them.

If a property is tunable, you can change its value at any time.

For more information on changing property values, see System Design in MATLAB Using System Objects.

Scope window name, specified as a character vector or string. The name appears in the title bar of the window.

Example: 'Multi-target Angle-Time Intensity Scope'

Tunable: Yes

Data Types: char | string

Location and size of the intensity scope window, specified as a 1-by-4 vector having the form [left bottom width height].

  • left and bottom specify the location of the bottom-left corner of the window.

  • width and height specify the width and height of the window.

Units are in pixels.

The default value of this property depends on the resolution of your display. By default, the window is positioned in the center of the screen with a width of 800 pixels and a height of 450 pixels.

Example: [100 100 500 400]

Tunable: Yes

Data Types: double

Input data type, specified as false or true. When true, the input consists of complex I/Q sample data and further processing is required to transform to the angle-time domain. When false, the input data is real response data that has already been transformed to the angle-time domain.

Data Types: logical

Angle-axis label, specified as a character vector or a string.

Example: 'Angles (rad)'

Tunable: Yes

Data Types: char | string

Angle separation between samples, specified as a positive scalar. This property defines the angle difference between columns of the input matrix. Units are in degrees.

Dependencies

To enable this property, set the IQDataInput property to false.

Data Types: double

Angle offset, specified as a scalar. This property defines the angle value of the first column of the input matrix. Units are in degrees.

Dependencies

To enable this property, set the IQDataInput property to false.

Data Types: double

Time interval between samples, specified as a positive scalar. This property defines the time interval between the rows of the scope. Units are in seconds.

Data Types: double

Time span of the intensity display, specified as a positive scalar. Units are in seconds.

Data Types: double

Response intensity units, specified as 'db', 'magnitude', or 'power'.

Data Types: char | string

Display title, specified as a character vector or string.

Tunable: Yes

Data Types: char | string

Sensor array, specified as a Phased Array System Toolbox array System object. See phased.ULA for the default values of a uniform linear array.

Example: phased.URA

Dependencies

To enable this property, set the IQDataInput to true.

Direction of arrival estimation method, specified as 'beamscan', 'mvdr', or 'music'.

Example: 'mvdr'

Dependencies

To enable this property, set the IQDataInput property to true.

Data Types: char | string

Signal propagation speed, specified as a positive scalar. The default value of this property is the speed of light. See physconst. Units are in meters/second.

Example: 3e8

Dependencies

To enable this property, set the IQDataInput property to true.

Data Types: double

Operating frequency of the system, specified as a positive scalar. Units are in Hz.

Example: 2e9

Dependencies

To enable this property, set the IQDataInput property to true.

Data Types: double

The number of bits used to quantize the phase shift of beamformer, specified as a non-negative integer. A value of zero indicates that no quantization is performed.

Example: 5

Dependencies

To enable this property, set the IQDataInput property to true.

Data Types: double

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

Dependencies

To enable this property, set the IQDataInput property to true.

Data Types: logical

Azimuth scan angles, specified as a scalar or real-valued row vector. The angles must lie between –180° and 180°, inclusive. Specify the angles in increasing order. At least one of the sets of angles defined in the AzimuthScanAngles and ElevationScanAngles properties must be a scalar. Units are in degrees.

Example: -20:20

Dependencies

To enable this property, set the IQDataInput property to true.

Data Types: double

Elevation scan angles, specified as a scalar or real-valued row vector. The angles must lie between –90° and 90°, inclusive. Specify the angles in increasing order. At least one of the sets of angles defined in the AzimuthScanAngles and ElevationScanAngles properties must be a scalar. Units are in degrees.

Dependencies

To enable this property, set the IQDataInput property to true.

Data Types: double

Usage

Syntax

Description

example

scope(X) displays an ATI scope of array response intensities derived from the data X. You can display magnitude or power values.

Input Arguments

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  • When the IQDataInput property is false, X represented intensity data, specified as an M-by-N real-valued matrix. Each column of the matrix represents an intensity vector from successive times. Each matrix row M is the number of intensity values in an angle intensity vector and N is the number of intensity vectors. M should be greater than 1 and N should be equal to or greater than 1. The time between the intensity vectors is specified in the TimeResolution property.

  • When the IQDataInput property is true X represented I/Q data, specified as an M-by-N complex-valued matrix. Each row contains the data samples for all sensors at a single time. Each column contains the I/Q data for one sensor for all times.

Object Functions

To use an object function, specify the System object as the first input argument. For example, to release system resources of a System object named obj, use this syntax:

release(obj)

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hideTurn off visibility of scope
isVisibleVisibility of scopes
showTurn on visibility of scopes
stepRun System object algorithm
releaseRelease resources and allow changes to System object property values and input characteristics
resetReset internal states of System object

Examples

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Display directions-of-arrival (DOA) of two signals arriving at a 10-by-5 uniform rectangular array (URA).

Create a URA array with isotropic antenna elements spaced 0.45 wavelengths apart.

fc = 200e6;
lambda = physconst('LightSpeed')/fc;
d = 0.45*lambda;
element = phased.IsotropicAntennaElement( ...
    FrequencyRange=[100e6,300e6]);
array = phased.URA(Element = element, ...
    Size = [10,5],ElementSpacing = [d,d]);

Then, create an ATIScope to process I/Q data.

scope = phased.ATIScope(IQDataInput = true, ...
    SensorArray = array, ...
    DOAMethod = "mvdr", ...
    OperatingFrequency = fc, ...
    AzimuthScanAngles = -50:50, ...
    ElevationScanAngles = 0, ...
    AngleLabel = "Azimuth Angle (deg)", ...
    TimeSpan = 100, ...
    TimeResolution = 2);

Generate baseband signals at 300 and 400 Hz. The sampling rate of the baseband signals is 8 kHz.

fs = 8000;
t = (0:1/fs:1).';
x1 = exp(-1i*2*pi*t*300);
x2 = exp(-1i*2*pi*t*400);

Create two paths in azimuth-elevation space. The first path is a straight line starting at -45 degrees in azimuth and stopping at 25 degrees with 50 samples. The second path has constant azimuth of 30 degrees.

path1 = [linspace(-45,25,50); 0.0*ones(1,50)];
path2 = [-10*ones(1,50);zeros(1,50)];
xtot = [x1,x2];
for k = 1:size(path2,2)
    azel1 = [path1(:,k),path2(:,k)];
    x = collectPlaneWave(array,xtot,azel1,fc);
    noise = 0.1*(randn(size(x)) + 1i*randn(size(x)));
    scope(x + noise);
end

Display directions-of-arrival (DOA) of two signals arriving at a 10-by-5 uniform rectangular array (URA).

First, create a URA array.

fc = 200e6;
lambda = physconst('LightSpeed')/fc;
d = 0.45*lambda;
element = phased.IsotropicAntennaElement(FrequencyRange=[100e6,300e6]);
array = phased.URA(Element = element,Size = [5,5],ElementSpacing = [d,d]);

Then, create an ATIScope.

scope = phased.ATIScope(IQDataInput = false, ...
    AngleLabel = "Azimuth Angle (deg)", ...
    TimeSpan = 100, ...
    TimeResolution = 2, ...
    AngleOffset = -90);
azAngle = -80:80;
elAngle = zeros(size(azAngle));
dirAngle = [azAngle;elAngle];

Generate baseband signals at 300 and 400 Hz. The sampling rate of the baseband signal is 8 kHz.

fs = 8000;
t = (0:1/fs:1).';
x1 = exp(-1i*2*pi*t*300);
x2 = exp(-1i*2*pi*t*400);

Create an MVDR beamformer object.

beamformer = phased.MVDRBeamformer('SensorArray',array,...
    'PropagationSpeed',physconst('LightSpeed'),'OperatingFrequency',fc,...
    'Direction',dirAngle,'WeightsOutputPort',false);

Create two paths in azimuth-elevation space. The first path is a straight line starting at -45 degrees in azimuth and stopping at 25 with 50 samples. The second path is at constant azimuth of 30 degrees.

path1 = [linspace(-45,25,71); 0.0*ones(1,71)];
path2 = [-10*ones(1,71); 0.0*ones(1,71)];
xtot = [x1,x2];
ymn = zeros(size(path2,2),161);
for k = 1:size(path2,2)
    azel1 = [path1(:,k),path2(:,k)];
    x = collectPlaneWave(array,xtot,azel1,fc);
    noise = 0.1*(randn(size(x)) + 1i*randn(size(x)));
    y = beamformer(x + noise);
    ymn(k,:) = mean(abs(y),1);
    scope(ymn)
end
scope(ymn)

More About

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Extended Capabilities

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Version History

Introduced in R2022b