LRT Detector
The LRT block is the receiver detection algorithm.
blockType: LRTDetector
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Path in the library: |
Description
Block LRT Detector Implements an algorithm for binary detection of signals in the presence of noise by the likelihood ratio test (LRT). The binary detector chooses between the null hypothesis and an alternative hypothesis based on data measurements. The null hypothesis means the absence of a signal, and the alternative hypothesis means the presence of some signal.
Ports
Input
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X
—
The input signal
N-by-1 real vector | N-by-1 complex vector' | `N-by-M real matrix | N-by-M complex matrix
Details
An input signal specified as a real or complex vector on or a real or complex matrix on . – the length of the signal, and – the number of data channels. Each data channel has samples to obtain the matrix on . Each row represents the components of a data vector of length .
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If , X represents a single data channel.
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If , X can represent counts from data channels.
Detection is performed by columns X. The size of each row it cannot change during simulation.
The LRT Detector block assumes the same signal model in each column X. The noise-free signal is contained in -a dimensional vector of data XK. Gaussian noise is added to each column, determined by the noise power nCoV. For this signal model, the LRT Detector determines whether or not to reject the null hypothesis Xk = 0. Since there is only one known signal model, LRT Detector outputs one detection result for each column X.
| Data types |
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| Complex numbers support |
Yes |
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XK
—
a known signal
real vector N by 1 | complex vector N by 1
Details
A known silent signal defined as a real or complex vector on .
| Data types |
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| Complex numbers support |
Yes |
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NCov
—
noise power
positive scalar
Details
The power or covariance of the noise, given as a positive scalar.
| Data types |
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| Complex numbers support |
No |
Output
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Y
—
detected output signal
logical vector 1 on M | integer vector 1 on L
Details
Detection results returned as a vector of boolean values on or an integer vector on . The value of Y depends on the value of the Output format parameter. By default, the Output format parameter has the value `Detection result'.
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If the Output format parameter is set to
Detection result, Y is a vector on , containing the logical detection results, where – the number of signal columns X. Y is true if there is a detection in the corresponding column X. Otherwise, Y is false. -
If the Output format parameter is set to
Detection index, Y is an integer vector on , containing the detection indexes, where – the number of detections found for all channels.
| Data types |
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| Complex numbers support |
Yes |
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Stat
—
detection statistics
matrix D by M | vector 1 by L
Details
Detection statistics returned as a matrix on or vectors on . The value of Stat depends on the setting of the Output format parameter.
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If the Output format parameter is set to
Detection result, Stat is a matrix on . -
If the Output format parameter is set to
Detection index, Stat is a vector on , containing detection statistics for each corresponding detection in Y.
Dependencies
To use this port, check the box Output detection statistics and threshold.
| Data types |
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| Complex numbers support |
Yes |
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Th
—
detection threshold
scalar
Details
The detection threshold returned as a scalar.
| Data types |
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| Complex numbers support |
Yes |
Parameters
Main
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Probability of false alarm —
the probability of a false alarm
Real number
Details
The probability of a false alarm, set as a positive scalar from 0 to `1'.
| Default value |
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| Program usage name |
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| Tunable |
No |
| Evaluatable |
Yes |
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Output format —
output data format
Detection result | Detection index
Details
The output data format is specified as Detection result or `Detection index'. The output data is returned to port Y.
| Values |
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| Default value |
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| Program usage name |
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| Tunable |
No |
| Evaluatable |
No |
#
Output detection statistics and threshold —
output of detection and threshold statistics
Logical
Details
Select this option to display detection statistics and detection threshold via ports Stat and Th.
| Default value |
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| Program usage name |
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| Tunable |
No |
| Evaluatable |
No |