Range-Angle Response

Obtain range-angle response map for array

  • Library:
  • Phased Array System Toolbox / Detection

Description

The Range-Angle Response block computes the range-angle map of an input signal. The output response is a matrix or a three-dimensional array whose rows represent range gates and columns represent angles. Pages represent

Ports

Input

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Input signal cube, specified as a complex-valued K-by-N matrix or complex-valued K-by-N-by-L array. The contents of the data cube depend on the type of range-angle processing specified by the different syntaxes.

  • K is the number of fast-time or range samples.

  • N is the number of independent spatial channels such as sensors or directions.

  • L is the slow-time dimension that corresponds to the number of pulses or sweeps in the input signal.

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.

Pulse repetition frequency

Dependencies

To enable this input argument, set the value of Range processing method to FFT and do not select the Dechirp input signal check box.

Data Types: double

Reference signal used for dechirping, specified as a complex-valued K-by-1 column vector. The number of rows must equal the length of the fast-time dimension of X.

Dependencies

To enable this input argument, set the value of Range processing method to FFT and select the Dechirp input signal check box.

Data Types: double
Complex Number Support: Yes

Matched filter coefficients, specified as a complex-valued P-by-1 column vector. P must be less than or equal to K. K is the number of fast-time or range sample.

Dependencies

To enable this input argument, set the value of Range processing method to Matched filter.

Data Types: double
Complex Number Support: Yes

Elevation angle of response, specified as a scalar between –90° and +90°. The range-angle response is computed for this elevation. Units are in degrees.

Dependencies

To enable this argument, set the Source of elevation angle parameter to Input port.

Data Types: double

Output

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Range response data cube, returned as one of the following:

  • Complex-valued M-element column vector

  • Complex-valued M-by-L matrix

  • Complex-valued M-by-N by-L array

The value of M depends on the type of processing

Range Processing MethodValue of M
FFT

If you set the Source of FFT length in range processing parameter to Auto, then M = K, the length of the fast-time dimension of X. Otherwise, M equals the value of the FFT length in range processing parameter.

Matched filterM = K, the length of the fast-time dimension of X.

Data Types: double
Complex Number Support: Yes

Range values along range dimension, returned as a real-valued M-by-1 column vector. This vector defines the ranges that correspond to the fast-time dimension of the RESP output data cube. M is the length of the fast-time dimension of RESP. Range values are monotonically increasing and equally spaced. Units are in meters.

Data Types: double

Angle values corresponding to the samples along angle direction, returned as a P-by-1 real-valued vector. Units are in degrees.

Data Types: double

Parameters

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Main Tab

Signal propagation speed, specified as a real-valued positive scalar. The default value of the speed of light is the value returned by physconst('LightSpeed'). Units are in meters per second.

Example: 3e8

Data Types: double

System operating frequency, specified as a positive scalar. Units are in Hz.

Range processing method, specified as Matched filter or FFT.

  • Matched filter — The object match-filters the incoming signal. This approach is commonly used for pulsed signals, where the matched filter is the time reverse of the transmitted signal.

  • FFT — The object applies an FFT to the input signal. This approach is commonly used for chirped signals such as FMCW and linear FM pulsed signals.

Data Types: char

Select this parameter to inherit the sample rate from upstream blocks. Otherwise, specify the sample rate using the Sample rate (Hz) parameter.

Data Types: Boolean

Specify the signal sampling rate as a positive scalar. Units are in Hz.

Dependencies

To enable this parameter, clear the Inherit sample rate check box.

Data Types: double

Linear FM sweep slope, specified as a scalar. The fast-time dimension of the X input port must correspond to sweeps having this slope.

Example: 1.5e9

Dependencies

To enable this parameter, set the Range processing method parameter to FFT.

Data Types: double

Option to enable dechirping of input signals, specified as on or off. Not selecting this check box indicates that the input signal is already dechirped and no dechirp operation is necessary. Select this check box when the input signal requires dechirping.

Dependencies

To enable this parameter, set the Range processing method parameter to FFT.

Data Types: Boolean

Source of the FFT length used for the range processing of dechirped signals, specified as Auto or Property.

  • Auto — The FFT length equals the length of the fast-time dimension of the input data cube.

  • Property — Specify the FFT length by using the FFT length in range processing parameter.

Dependencies

To enable this parameter, set the Range processing method parameter to FFT.

Data Types: char

FFT length used for range processing, specified as a positive integer.

Dependencies

To enable this parameter, set the Range processing method parameter to FFT and the Source of FFT length in range processing parameter to Property.

Data Types: double

FFT weighting window for range processing, specified as None, Hamming, Chebyshev, Hann, Kaiser, or Taylor.

If you set this parameter to Taylor, the generated Taylor window has four nearly constant sidelobes next to the mainlobe.

Dependencies

To enable this parameter, set the Range processing method parameter to FFT.

Data Types: char

Sidelobe attenuation for range processing, specified as a positive scalar. This attenuation applies only to Kaiser, Chebyshev, or Taylor windows. Units are in dB.

Dependencies

To enable this parameter, set the Range processing method parameter to FFT and the Range processing window parameter to Kaiser, Chebyshev, or Kaiser.

Set reference range at center of range grid, specified as on or off. Selecting this check box enables you to set the reference range at the center of the range grid. Otherwise, the reference range corresponds to the beginning of the range grid.

Dependencies

To enable this parameter, set the Range processing method to FFT.

Data Types: Boolean

Reference range of the range grid, specified as a nonnegative scalar.

  • If you set the Range processing method parameter to 'Matched filter', the reference range is set to the start of the range grid.

  • If you set the Range processing method parameter to FFT, the reference range is determined by the Set reference range at center parameter.

    • When you select the Set reference range at center check box, the reference range is set to the center of the range grid.

    • Otherwise, the reference range is set to the start of the range grid.

    Units are in meters.

Example: 1000.0

Data Types: double

Source of elevation angle, specified as Property or Input port.

PropertyThe elevation angle comes from the Elevation angle (deg) parameter.
Input portThe elevation angle comes from an input port.

Elevation angle used to calculate range-angle response, specified as a scalar. The angle must be between --90 and 90 degrees. This property applies when you set the ElevationAngleSource property to 'Property'. The default value of this property is 0.

Angle response span, specified as a real-valued 2-by-1 vector. The object calculates the range-angle response within the angle range, [min_angle max_angle].

Example: [-45 45]

Data Types: 12wqqqq` | qdouble

Number of samples in angle span used to calculate range-angle response, specified as a positive integer greater than two.

Example: [256]

Data Types: double

Block simulation, specified as Interpreted Execution or Code Generation. If you want your block to use the MATLAB® interpreter, choose Interpreted Execution. If you want your block to run as compiled code, choose Code Generation. Compiled code requires time to compile but usually runs faster.

Interpreted execution is useful when you are developing and tuning a model. The block runs the underlying System object™ in MATLAB. You can change and execute your model quickly. When you are satisfied with your results, you can then run the block using Code Generation. Long simulations run faster than in interpreted execution. You can run repeated executions without recompiling, but if you change any block parameters, then the block automatically recompiles before execution.

This table shows how the Simulate using parameter affects the overall simulation behavior.

When the Simulink® model is in Accelerator mode, the block mode specified using Simulate using overrides the simulation mode.

Acceleration Modes

Block SimulationSimulation Behavior
NormalAcceleratorRapid Accelerator
Interpreted ExecutionThe block executes using the MATLAB interpreter.The block executes using the MATLAB interpreter.Creates a standalone executable from the model.
Code GenerationThe block is compiled.All blocks in the model are compiled.

For more information, see Choosing a Simulation Mode (Simulink).

Sensor Arrays Tab

Method to specify array, specified as Array (no subarrays) or MATLAB expression.

  • Array (no subarrays) — use the block parameters to specify the array.

  • Partitioned array — use the block parameters to specify the array.

  • Replicated subarray — use the block parameters to specify the array.

  • MATLAB expression — create the array using a MATLAB expression.

MATLAB expression used to create an array, specified as a valid Phased Array System Toolbox array System object.

Example: phased.URA('Size',[5,3])

Dependencies

To enable this parameter, set Specify sensor array as to MATLAB expression.

Element Parameters

Antenna or microphone type, specified as one of the following:

  • Isotropic Antenna

  • Cosine Antenna

  • Custom Antenna

  • Omni Microphone

  • Custom Microphone

Specify the operating frequency range of the antenna or microphone element as a 1-by-2 row vector in the form [LowerBound,UpperBound]. The element has no response outside this frequency range. Frequency units are in Hz.

Dependencies

To enable this parameter, set Element type to Isotropic Antenna, Cosine Antenna, or Omni Microphone.

Specify the frequencies at which to set antenna and microphone frequency responses as a 1-by-L row vector of increasing real values. The antenna or microphone element has no response outside the frequency range specified by the minimum and maximum elements of this vector. Frequency units are in Hz.

Dependencies

To enable this parameter, set Element type to Custom Antenna or Custom Microphone. Use Frequency responses (dB) to set the responses at these frequencies.

Select this check box to baffle the back response of the element. When back baffled, the responses at all azimuth angles beyond ±90° from broadside are set to zero. The broadside direction is defined as 0° azimuth angle and 0° elevation angle.

Dependencies

To enable this check box, set Element type to Isotropic Antenna or Omni Microphone.

Specify the exponents of the cosine pattern as a nonnegative scalar or a real-valued 1-by-2 matrix of nonnegative values. When Exponent of cosine pattern is a 1-by-2 vector, the first element is the exponent in the azimuth direction and the second element is the exponent in the elevation direction. When you set this parameter to a scalar, both the azimuth direction and elevation direction cosine patterns are raised to the same power.

Dependencies

To enable this parameter, set Element type to Cosine Antenna.

Frequency response of a custom antenna or custom microphone for the frequencies defined by the Operating frequency vector (Hz) parameter. The dimensions of Frequency responses (dB) must match the dimensions of the vector specified by the Operating frequency vector (Hz) parameter.

Dependencies

To enable this parameter, set Element type to Custom Antenna or Custom Microphone.

Specify the azimuth angles at which to calculate the antenna radiation pattern as a 1-by-P row vector. P must be greater than 2. Azimuth angles must lie between –180° and 180°, inclusive, and be in strictly increasing order.

Dependencies

To enable this parameter, set Element type to Custom Antenna.

Specify the elevation angles at which to compute the radiation pattern as a 1-by-Q vector. Q must be greater than 2. Angle units are in degrees. Elevation angles must lie between –90° and 90°, inclusive, and be in strictly increasing order.

Dependencies

To enable this parameter, set Element type to Custom Antenna.

Magnitude of the combined antenna radiation pattern, specified as a Q-by-P matrix or a Q-by-P-by-L array. The quantity Q equals the length of the vector specified by Elevation angles (deg). The quantity P equals length of the vector specified by Azimuth angles (deg). The quantity L equals the length of the Operating frequency vector (Hz).

  • If this parameter is a Q-by-P matrix, the same pattern is applied to all frequencies specified in the Operating frequency vector (Hz) parameter.

  • If the value is a Q-by-P-by-L array, each Q-by-P page of the array specifies a pattern for the corresponding frequency specified in the Operating frequency vector (Hz) parameter.

Dependencies

To enable this parameter, set Element type to Custom Antenna.

Phase of the combined antenna radiation pattern, specified as a Q-by-P matrix or a Q-by-P-by-L array. The quantity Q equals the length of the vector specified by Elevation angles (deg). The quantity P equals length of the vector specified by Azimuth angles (deg). The quantity L equals the length of the Operating frequency vector (Hz).

  • If this parameter is a Q-by-P matrix, the same pattern is applied to all frequencies specified in the Operating frequency vector (Hz) parameter.

  • If the value is a Q-by-P-by-L array, each Q-by-P page of the array specifies a pattern for the corresponding frequency specified in the Operating frequency vector (Hz) parameter.

Dependencies

To enable this parameter, set Element type to Custom Antenna.

Polar pattern microphone response frequencies, specified as a real scalar, or a real-valued, 1-by-L vector. The response frequencies lie within the frequency range specified by the Operating frequency vector (Hz) vector.

Dependencies

To enable this parameter, set Element type set to Custom Microphone.

Specify the polar pattern response angles, as a 1-by-P vector. The angles are measured from the central pickup axis of the microphone and must be between –180° and 180°, inclusive.

Dependencies

To enable this parameter, set Element type to Custom Microphone.

Specify the magnitude of the custom microphone element polar patterns as an L-by-P matrix. L is the number of frequencies specified in Polar pattern frequencies (Hz). P is the number of angles specified in Polar pattern angles (deg). Each row of the matrix represents the magnitude of the polar pattern measured at the corresponding frequency specified in Polar pattern frequencies (Hz) and all angles specified in Polar pattern angles (deg). The pattern is measured in the azimuth plane. In the azimuth plane, the elevation angle is 0° and the central pickup axis is 0° degrees azimuth and 0° degrees elevation. The polar pattern is symmetric around the central axis. You can construct the microphone response pattern in 3-D space from the polar pattern.

Dependencies

To enable this parameter, set Element type to Custom Microphone.

Array Parameters

Array geometry, specified as one of

  • ULA — Uniform linear array

  • URA — Uniform rectangular array

  • UCA — Uniform circular array

  • Conformal Array — arbitrary element positions

The number of array elements for ULA or UCA arrays, specified as an integer greater than or equal to 2.

When you set Specify sensor array as to Replicated subarray, this parameter applies to each subarray.

Dependencies

To enable this parameter, set Geometry to ULA or UCA.

Spacing between adjacent array elements:

  • ULA — specify the spacing between two adjacent elements in the array as a positive scalar.

  • URA — specify the spacing as a positive scalar or a 1-by-2 vector of positive values. If Element spacing (m) is a scalar, the row and column spacings are equal. If Element spacing (m) is a vector, the vector has the form [SpacingBetweenArrayRows,SpacingBetweenArrayColumns].

  • When you set Specify sensor array as to Replicated subarray, this parameter applies to each subarray.

Dependencies

To enable this parameter, set Geometry to ULA or URA.

Linear axis direction of ULA, specified as y, x, or z. All ULA array elements are uniformly spaced along this axis in the local array coordinate system.

Dependencies

  • To enable this parameter, set Geometry to ULA.

  • This parameter is also enabled when the block only supports ULA arrays.

Dimensions of a URA array, specified as a positive integer or 1-by-2 vector of positive integers.

  • If Array size is a 1-by-2 vector, the vector has the form [NumberOfArrayRows,NumberOfArrayColumns].

  • If Array size is an integer, the array has the same number of rows and columns.

  • When you set Specify sensor array as to Replicated subarray, this parameter applies to each subarray.

For a URA, array elements are indexed from top to bottom along the leftmost column, and then continue to the next columns from left to right. In this figure, the Array size value of [3,2] creates an array having three rows and two columns.

Dependencies

To enable this parameter, set Geometry to URA.

Lattice of URA element positions, specified as Rectangular or Triangular.

  • Rectangular — Aligns all the elements in row and column directions.

  • Triangular — Shifts the even-row elements of a rectangular lattice toward the positive row-axis direction. The displacement is one-half the element spacing along the row dimension.

Dependencies

To enable this parameter, set Geometry to URA.

Array normal direction, specified as x, y, or z.

Elements of planar arrays lie in a plane orthogonal to the selected array normal direction. Element boresight directions point along the array normal direction.

Array Normal Parameter ValueElement Positions and Boresight Directions
xArray elements lie in the yz-plane. All element boresight vectors point along the x-axis.
yArray elements lie in the zx-plane. All element boresight vectors point along the y-axis.
zArray elements lie in the xy-plane. All element boresight vectors point along the z-axis.

Dependencies

To enable this parameter, set Geometry to URA or UCA.

Radius of UCA array, specified as a positive scalar.

Dependencies

To enable this parameter, set Geometry to UCA.

Positions of the elements in a conformal array, specified as a 3-by-N matrix of real values, where N is the number of elements in the conformal array. Each column of this matrix represents the position [x;y;z]of an array element in the array local coordinate system. The origin of the local coordinate system is (0,0,0). Units are in meters.

When you set Specify sensor array as to Replicated subarray, this parameter applies to each subarray.

Dependencies

To enable this parameter set Geometry to Conformal Array.

Direction of element normal vectors in a conformal array, specified as a 2-by-1 column vector or a 2-by-N matrix. N indicates the number of elements in the array. For a matrix, each column specifies the normal direction of the corresponding element in the form [azimuth;elevation] with respect to the local coordinate system. The local coordinate system aligns the positive x-axis with the direction normal to the conformal array. If the parameter value is a 2-by-1 column vector, the same pointing direction is used for all array elements.

When you set Specify sensor array as to Replicated subarray, this parameter applies to each subarray.

You can use the Element positions (m) and Element normals (deg) parameters to represent any arrangement in which pairs of elements differ by certain transformations. The transformations can combine translation, azimuth rotation, and elevation rotation. However, you cannot use transformations that require rotation about the normal direction.

Dependencies

To enable this parameter, set Geometry to Conformal Array.

Element tapering, specified as a complex-valued scalar or a complex-valued 1-by-N row vector. In this vector, N represents the number of elements in the array.

Also known as element weights, tapers multiply the array element responses. Tapers modify both amplitude and phase of the response to reduce side lobes or steer the main response axis.

If Taper is a scalar, the same weight is applied to each element. If Taper is a vector, a weight from the vector is applied to the corresponding sensor element. The number of weights must match the number of elements of the array.

When you set Specify sensor array as to Replicated subarray, this parameter applies to each subarray.

Specify the subarray selection as an M-by-N matrix. M is the number of subarrays and N is the total number of elements in the array. Each row of the matrix represents a subarray and each entry in the row indicates when an element belongs to the subarray. When the entry is zero, the element does not belong the subarray. A nonzero entry represents a complex-valued weight applied to the corresponding element. Each row must contain at least one nonzero entry.

The phase center of each subarray lies at the subarray geometric center. The subarray geometric center depends on the Subarray definition matrix and Geometry parameters.

Dependencies

To enable this parameter, set Specify sensor array as to Partitioned array.

Subarray steering method, specified as one of

  • None

  • Phase

  • Time

  • Custom

Selecting Phase or Time opens the Steer input port on the Narrowband Receive Array, Narrowband Transmit Array, Wideband Receive Array, Wideband Transmit Array blocks, Constant Gamma Clutter, and GPU Constant Gamma Clutter blocks.

Selecting Custom opens the WS input port on the Narrowband Receive Array, Narrowband Transmit Array, Wideband Receive Array, Wideband Transmit Array blocks, Constant Gamma Clutter, and GPU Constant Gamma Clutter blocks.

Dependencies

To enable this parameter, set Specify sensor array as to Partitioned array or Replicated subarray.

Operating frequency of subarray steering phase shifters, specified as a positive real-valued scalar. Units are Hz.

Dependencies

To enable this parameter, set Sensor array to Partitioned array or Replicated subarray and set Subarray steering method to Phase.

Subarray steering phase shift quantization bits, specified as a non-negative integer. A value of zero indicates that no quantization is performed.

Dependencies

To enable this parameter, set Sensor array to Partitioned array or Replicated subarray and set Subarray steering method to Phase.

Specify the layout of replicated subarrays as Rectangular or Custom.

  • When you set this parameter to Rectangular, use the Grid size and Grid spacing parameters to place the subarrays.

  • When you set this parameter to Custom, use the Subarray positions (m) and Subarray normals parameters to place the subarrays.

Dependencies

To enable this parameter, set Sensor array to Replicated subarray

Rectangular subarray grid size, specified as a single positive integer, or a 1-by-2 row vector of positive integers.

If Grid size is an integer scalar, the array has an equal number of subarrays in each row and column. If Grid size is a 1-by-2 vector of the form [NumberOfRows, NumberOfColumns], the first entry is the number of subarrays along each column. The second entry is the number of subarrays in each row. A row is along the local y-axis, and a column is along the local z-axis. The figure here shows how you can replicate a 3-by-2 URA subarray using a Grid size of [1,2].

Dependencies

To enable this parameter, set Sensor array to Replicated subarray and Subarrays layout to Rectangular.

The rectangular grid spacing of subarrays, specified as a positive, real-valued scalar, a 1-by-2 row vector of positive, real-values, or Auto. Units are in meters.

  • If Grid spacing is a scalar, the spacing along the row and the spacing along the column is the same.

  • If Grid spacing is a 1-by-2 row vector, the vector has the form [SpacingBetweenRows,SpacingBetweenColumn]. The first entry specifies the spacing between rows along a column. The second entry specifies the spacing between columns along a row.

  • If Grid spacing is set to Auto, replication preserves the element spacing of the subarray for both rows and columns while building the full array. This option is available only when you specify Geometry as ULA or URA.

Dependencies

To enable this parameter, set Sensor array to Replicated subarray and Subarrays layout to Rectangular.

Positions of the subarrays in the custom grid, specified as a real 3-by-N matrix, where N is the number of subarrays in the array. Each column of the matrix represents the position of a single subarray in the array local coordinate system. The coordinates are expressed in the form [x; y; z]. Units are in meters.

Dependencies

To enable this parameter, set Sensor array to Replicated subarray and Subarrays layout to Custom.

Specify the normal directions of the subarrays in the array. This parameter value is a 2-by-N matrix, where N is the number of subarrays in the array. Each column of the matrix specifies the normal direction of the corresponding subarray, in the form [azimuth;elevation]. Angle units are in degrees. Angles are defined with respect to the local coordinate system.

You can use the Subarray positions and Subarray normals parameters to represent any arrangement in which pairs of subarrays differ by certain transformations. The transformations can combine translation, azimuth rotation, and elevation rotation. However, you cannot use transformations that require rotation about the normal.

Dependencies

To enable this parameter, set the Sensor array parameter to Replicated subarray and the Subarrays layout to Custom.

Introduced in R2018b