Two-dimensional CFAR detector
The phased.CFARDetector2D
System
object™ implements a constant
false-alarm rate detector (CFAR) for selected elements (called cells)
of two-dimensional image data. A detection is declared when an image
cell value exceeds a threshold. To maintain a constant false alarm-rate,
the threshold is set to a multiple of the image noise power. The detector
estimates noise power for a cell-under-test (CUT) from
surrounding cells using one of three cell averaging methods, or an
order statistics method. The cell-averaging methods are cell averaging
(CA), greatest-of cell averaging (GOCA), or smallest-of cell averaging
(SOCA).
For each test cell, the detector:
estimates the noise statistic from the cell values in the training band surrounding the CUT cell.
computes the threshold by multiplying the noise estimate by the threshold factor.
compares the CUT cell value to the threshold to determine whether a target is present or absent. If the value is greater than the threshold, a target is present.
To run the detector
Define and set up your 2-D CFAR detector. You can
set the phased.CFARDetector2D
System
object properties
when you create the object, or leave them set to their default values.
See Construction. Some properties
that you set at construction time can be changed later. These properties
are tunable.
Find the detections by calling the step
method.
The output of this method depends on the properties of the phased.CFARDetector2D
System
object.
Alternatively, instead of using the step
method
to perform the operation defined by the System
object, you can
call the object with arguments, as if it were a function. For example, y
= step(obj,x)
and y = obj(x)
perform
equivalent operations.
creates
a 2-D CFAR detector System
object, detector
= phased.CFARDetector2Ddetector
.
creates
a 2-D CFAR System
object, detector
= phased.CFARDetector2D(Name
,Value
)detector
, with
each specified property Name
set to the specified Value
.
You can specify additional name-value pair arguments in any order
as (Name1
,Value1
,...,NameN
,ValueN
).
reset | Reset states of System object |
step | Two-dimensional CFAR detection |
Common to All System Objects | |
---|---|
release | Allow System object property value changes |
[1] Mott, H. Antennas for Radar and Communications. New York: John Wiley & Sons, 1992.
[2] Richards, M. A. Fundamentals of Radar Signal Processing. New York: McGraw-Hill, 2005.
[3] Skolnik, M. Introduction to Radar Systems, 3rd Ed. New York: McGraw-Hill, 2001.