ULA Beamscan Spectrum
Beamscan spatial spectrum estimator for ULA
Libraries:
Phased Array System Toolbox /
Direction of Arrival
Description
The ULA Beamscan Spectrum block estimates the spatial spectrum of incoming narrowband signals by scanning a region of broadside angles using a narrowband conventional beamformer applied to a uniform linear array. The block optionally calculates the direction of arrival of a specified number of signals by estimating peaks of the spectrum.
Ports
Input
Port 1 — Received signal
M-by-N complex-valued matrix
Received signal, specified as an M-by-N complex-valued matrix. The quantity M is the number of sample values (snapshots) contained in the signal and N is the number of sensor elements in the array.
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.
Data Types: double
Complex Number Support: Yes
Output
Y — Beamscan spatial spectrum
non-negative, real-valued column vector
Beamscan spatial spectrum, returned as a non-negative, real-valued column vector representing the magnitude of the estimated beamscan spatial spectrum. Each entry corresponds to an angle specified by the Scan angles (deg) parameter.
Data Types: double
Ang — Directions of arrival
non-negative, real-valued column vector
Directions of arrival of the signals, returned as a real-valued row vector. The
direction of arrival angle is the broadside angle between the source direction and the
array axis. Angle units are in degrees. The length of the vector is the number of
signals specified by the Number of signals parameter. If the
object cannot identify peaks in the spectrum, it will return
NaN
.
Dependencies
To enable this output port, select the Enable DOA output check box.
Data Types: double
Parameters
Signal propagation speed (m/s) — Signal propagation speed
physconst('LightSpeed')
(default) | real-valued positive scalar
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
Operating frequency (Hz) — System operating frequency
3e8
(default) | positive real scalar
System operating frequency, specified as a positive scalar. Units are in Hz.
Number of bits in phase shifters — Number of phase shift quantization bits
0
(default) | nonnegative integer
The number of bits used to quantize the phase shift component of beamformer or steering vector weights. Specify the number of bits as a non-negative integer. A value of zero indicates that no quantization is performed.
Forward-backward averaging — Enable forward-backward averaging
off (default) | on
Select this parameter to use forward-backward averaging to estimate the covariance matrix for sensor arrays with a conjugate symmetric array manifold structure.
Spatial smoothing — Enable spatial smoothing
0
(default) | non-negative integer
Specify the amount of averaging used by spatial smoothing to estimate the covariance matrix as a nonnegative integer. Each increase in smoothing handles one extra coherent source, but reduces the effective number of elements by one. The maximum value of this parameter is N – 2, where N is the number of sensors in the ULA.
Scan angles (deg) — Search angles for spectrum peaks
-90:90
(default) | real-valued row vector
Specify the scan angles in degrees as a real-valued row vector. The angles are array broadside angles and must lie between –90° and 90°, inclusive. You must specify the angles in increasing order.
Enable DOA output — Output directions of arrival through output port
off (default) | on
Select this parameter to output the signals directions of arrival (DOA) through the Ang output port.
Number of signals — Expected number of arriving signals
1
(default) | positive integer
Specify the expected number of signals for DOA estimation as a positive scalar integer.
Dependencies
To enable this parameter, select the Enable DOA output check box.
Data Types: double
Simulate using — Block simulation method
Interpreted Execution
(default) | Code Generation
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 with generated code 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 Simulation | Simulation Behavior | ||
Normal | Accelerator | Rapid Accelerator | |
Interpreted Execution | The block executes using the MATLAB interpreter. | The block executes using the MATLAB interpreter. | Creates a standalone executable from the model. |
Code Generation | The block is compiled. | All blocks in the model are compiled. |
For more information, see Choosing a Simulation Mode (Simulink).
Programmatic Use
Block
Parameter:SimulateUsing |
Type:enum |
Values:Interpreted
Execution , Code Generation |
Default:Interpreted
Execution |
Specify sensor array as — Method to specify array
Array (no subarrays)
(default) | MATLAB expression
Method to specify array, specified as Array (no subarrays)
or MATLAB expression
.
Array (no subarrays)
— use the block parameters to specify the array.MATLAB expression
— create the array using a MATLAB expression.
Expression — MATLAB expression used to create an array
Phased Array System Toolbox™ array System object
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 type — Array element types
Isotropic Antenna
(default) | Cosine Antenna
| Custom Antenna
| Omni Microphone
| Custom Microphone
Antenna or microphone type, specified as one of the following:
Isotropic Antenna
Cosine Antenna
Custom Antenna
Omni Microphone
Custom Microphone
Operating frequency range (Hz) — Operating frequency range of the antenna or microphone element
[0,1e20]
(default) | real-valued 1-by-2 row vector
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
.
Operating frequency vector (Hz) — Operating frequency range of custom antenna or microphone elements
[0,1e20]
(default) | real-valued row vector
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.
Baffle the back of the element — Set back response of an Isotropic Antenna
element or an Omni Microphone
element to
zero
off (default) | on
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
.
Exponent of cosine pattern — Exponents of azimuth and elevation cosine patterns
[1.5 1.5]
(default) | nonnegative scalar | real-valued 1-by-2 matrix of nonnegative values
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 responses (dB) — Antenna and microphone frequency response
[0,0]
(default) | real-valued row vector
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
.
Input Pattern Coordinate System — Coordinate system of custom antenna pattern
az-el
(default) | phi-theta
Coordinate system of custom antenna pattern, specified
az-el
or phi-theta
. When you
specify az-el
, use the Azimuth angles
(deg) and Elevations angles (deg) parameters to
specify the coordinates of the pattern points. When you specify
phi-theta
, use the Phi angles (deg)
and Theta angles (deg) parameters to specify the coordinates of the
pattern points.
Dependencies
To enable this parameter, set Element type to
Custom Antenna
.
Azimuth angles (deg) — Azimuth angles of antenna radiation pattern
[-180:180]
(default) | real-valued row vector
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 the Element type
parameter to Custom Antenna
and the
Input Pattern Coordinate System
parameter to az-el
.
Elevation angles (deg) — Elevation angles of antenna radiation pattern
[-90:90]
(default) | real-valued row vector
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 the Element type
parameter to Custom Antenna
and the
Input Pattern Coordinate System
parameter to az-el
.
Phi Angles (deg) — Phi angle coordinates of custom antenna radiation pattern
0:360
| real-valued 1-by-P row vector
Phi angles of points at which to specify the antenna radiation pattern, specify as a real-valued 1-by-P row vector. P must be greater than 2. Angle units are in degrees. Phi angles must lie between 0° and 360° and be in strictly increasing order.
Dependencies
To enable this parameter, set the Element type parameter to
Custom Antenna
and the Input Pattern Coordinate
System parameter to phi-theta
.
Theta Angles (deg) — Theta angle coordinates of custom antenna radiation pattern
0:180
| real-valued 1-by-Q row vector
Theta angles of points at which to specify the antenna radiation pattern, specify as a real-valued 1-by-Q row vector. Q must be greater than 2. Angle units are in degrees. Theta angles must lie between 0° and 360° and be in strictly increasing order.
Dependencies
To enable this parameter, set the Element type parameter to
Custom Antenna
and the Input Pattern Coordinate
System parameter to phi-theta
.
Radiation pattern (dB) — Custom antenna radiation pattern
zeros(181,361)
| complex-valued matrix | complex-valued MATLAB array
Magnitude of the combined polarized antenna radiation pattern, specified as a Q-by-P matrix or a Q-by-P-by-L array. The value of Q must equal the value of Q specified by Elevation angles (deg). The value of P must equal the value of P specified by Azimuth angles (deg). The value of L must equal the value of L specified by Operating frequency vector (Hz).
Dependencies
To enable this parameter, set Element type to Custom
Antenna
.
Polar pattern frequencies (Hz) — Polar pattern microphone response frequencies
1e3 (default) | real scalar | real-valued 1-by-L row vector
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
.
Polar pattern angles (deg) — Polar pattern response angles
[-180:180]
(default) | real-valued -by-P row vector
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
.
Polar pattern (dB) — Custom microphone polar response
zeros(1,361)
(default) | real-valued L-by-P matrix
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
.
Number of elements — Number of array elements in U
2
(default) | positive integer greater than or equal to two
The number of array elements for ULA arrays, specified as an integer greater than or equal to two.
Example: 11
Data Types: double
Element spacing — Distance between ULA elements
0.5
(default) | positive scalar
Distance between adjacent ULA elements, specified as a positive scalar. Units are in meters.
Example: 1.5
Array axis — Linear axis direction of ULA
y
(default) | x
| z
Linear axis direction of ULA, specified as y
, x
,
or z
. Then, all ULA array elements are
uniformly spaced along this axis in the local array coordinate system.
Taper — Array element tapers
1 (default) | complex scalar | complex-valued row vector
Specify element tapering 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.
Data Types: double
Version History
Introduced in R2014b
See Also
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