LRT Detector
Libraries:
Phased Array System Toolbox /
Detection
Description
The likelihood ratio test (LRT) detector performs binary signal detection in the presence of noise. The binary detector chooses between the null hypothesis H0 and the alternative hypothesis H1 based on data measurements. The null hypothesis denotes the absence of any signal while the alternative hypothesis denotes the presence of some signal.
Ports
Input
X — Input data
real-valued N-by-1 vector | complex-valued N-by-1 vector | real-valued N-by-M matrix | complex-valued N-by-M matrix
Input data, specified as a real-valued or complex-valued
N-by-1 vector, or an
N-by-M real-valued or complex-valued matrix.
N is the signal length and M is the number of
data channels. Each data channel has N samples to yield an
N-by-M matrix. Each row represents the
components of a length-M data vector. When M =
1, X
represents a single channel of data. When
M > 1, X
can represent N
samples from M data channels. Detection is performed along the
columns of X
. The size of each row M cannot
change during the simulation.
The LRT detector assumes the same signal model in each column of
X
. The noise-free signal is contained in the
N-dimensional data vector Xknown
. Gaussian
noise, defined by the noise power NCov
, is added to each column.
For this signal model, the LRT detector determines whether or not to reject the null
hypothesis Xknown
= 0
. Because there is only
one known signal model, the LRT detector outputs one detection result for each column
of X
.
Data Types: single
| double
Complex Number Support: Yes
XK — Known signal
real-valued N-by-1 vector | complex-valued N-by-1 vector
Known noise-free signal, specified as a real-valued or complex-valued N-by-1 vector.
Data Types: single
| double
Complex Number Support: Yes
NCov — Noise power
positive scalar
Noise power or covariance, specified as a positive scalar.
Example: 2.0
Data Types: single
| double
Output
Y — Detection results
1-by-M logical-valued vector | 1-by-L integer-valued vector
Detection results, returned as a 1-by-M logical-valued vector
or a 1-by-L integer-valued vector. The format of
Y
depends on the value of the Output
format parameter. By default, the Output format
parameter is set to 'Detection result'
.
When the Output format parameter is set to
'Detection result'
,Y
is a 1-by-M vector containing logical detection results, where M is the number of columns ofX
.Y
istrue
if there is a detection in the corresponding column ofX
. Otherwise,Y
isfalse
.When the Output format parameter is set to
'Detection index'
,Y
is a 1-by-L integer-valued vector containing detection indices, where L is the number of detections found over all M channels.
Data Types: single
| double
| Boolean
Complex Number Support: Yes
Stat — Detection statistics
D-by-M (default) | matrix | 1-by-L vector
Detection statistics, returned as a D-by-M
matrix or as a 1-by-L vector. The format of
stat
depends on the setting of the Output
format parameter.
When Output format parameter is
'Detection result'
,stat
is a D-by-M matrix.When Output format parameter is
'Detection index'
,stat
is a 1-by-L vector containing detection statistics for each corresponding detection in Y.
Dependencies
To enable this port, select the Output detection statistics and threshold check box.
Data Types: single
| double
Complex Number Support: Yes
Th — Detection threshold
scalar
Detection threshold, returned as a scalar.
Dependencies
To enable this port, select the Output detection statistics and threshold check box.
Data Types: single
| double
Parameters
Probability of false alarm — Probability of false alarm
0.1
(default) | nonnegative scalar
Probability of false alarm, specified as positive scalar between 0 and 1, inclusive.
Programmatic Use
Block
Parameter:ProbabilityFalseAlarm |
Type:double, single |
Values:scalar | |
Default:0.1 |
Data Types: single
| double
Output format — Format of output data
Detection result
(default) | Detection index
Format of output data, specified as Detection result
or
Detection index
. Output data is returned in the
Y
port.
Example: Detection index
Programmatic Use
Block
Parameter:OutputFormat |
Type:char, string |
Values:Detection result |
Detection index |
Default:Detection
result |
Data Types: char
| string
Output detection statistics and threshold — Output detection statistics and threshold
false
(default) | true
Select this checkbox to output detection statistics and detection threshold using the Stat and Th ports.
Programmatic Use
Block
Parameter:ThresholdOutputPort |
Type:check box |
Values:0 | 1 |
Default:0 |
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 |
Extended Capabilities
C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.
Version History
Introduced in R2023b
See Also
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