radarmetricplot
Syntax
Description
radarmetricplot(___,
specifies additional Name,Value
)Name,Value
arguments.
Example: 'MaxRangeRequirement',125e3,'MetricName','Available SNR'
specifies the maximum range requirement to be 125000 m, and the metric name to be
'Available SNR'
returns
the handle to the axes in the figure.h
= radarmetricplot(___)
Examples
Plot Available SNR and Detectability Factor
For a radar system, plot the available SNR and the detectability factor against the target range. Mark the required maximum range. Use the stoplight chart to assess the detection performance of the system at different ranges.
Scenario Parameters
Define the scenario parameters.
lambda = freq2wavelen(3e9); % Wavelength (m) Pt = 5e3; % Peak power (W) tau = 1.2e-5; % Pulse width (s) N = 24; % Number of received pulses SwerlingCase = 'Swerling1'; % Swerling case G = 40; % Antenna gain (dB) Pfa = 1e-6; % Pfa
Requirements
Specify the probability of detection to be 0.9 and the maximum range to be 125000 m.
Pd = 0.9; % Required Pd MaxRangeRq = 125e3; % Maximum range requirement (m)
Specify the range points to evaluate the radar equation.
R = (1:1e2:200e3).';
Compute Performance Metric and Requirement
Compute the available SNR and the detectability factor.
Compute the available SNR from the radar equation using the radareqsnr
function.
SNRav = radareqsnr(lambda,R,Pt,tau,'Gain',G);
Compute the detectability factor using the detectability
function.
DxObj = detectability(Pd,Pfa,N,SwerlingCase)
DxObj = 10.9850
Plot Performance Metric and Requirement
Plot the available SNR in dB and the detectability factor against the target range using the radarmetricplot
function. In order to plot, specify the 'MaxRangeRequirement'
to be 125000 m. Set 'ShowStoplight'
to true
to show a stoplight chart that color codes the area of the plot according to the specified requirements.
radarmetricplot(R,SNRav,DxObj,'MaxRangeRequirement',MaxRangeRq, ... 'MetricName','Available SNR','MetricUnit','dB',... 'RequirementName','Detectability','ShowStoplight',true) ylim([0 40])
Input Arguments
range
— Target ranges
column vector
Target ranges at which the metric is computed, specified as a length-J column vector, where J is the number of target ranges.
Data Types: double
metric
— Radar performance metric values
matrix
Radar performance metric values, specified as a
J-by-K matrix, where J is the
length of the target range vector range
and K is
the number of radars.
Data Types: double
objective
— Objective requirement
scalar | vector | matrix
Objective requirement, specified as one of the following:
scalar –– The objective requirement is assumed to be constant across all ranges in
range
and equal for all K radars.1-by-K vector –– The objective requirement is specified for each radar and is assumed to be constant for all ranges in
range
.J-by-1 vector –– The objective requirement is specified for each range in
range
and is assumed to be equal for all K radars.J-by-K matrix –– The objective requirement is specified for each range in
range
and for each radar.
Data Types: double
threshold
— Threshold requirement
scalar | vector | matrix
Threshold requirement, specified as one of the following:
scalar –– The threshold requirement is assumed to be constant across all ranges in
range
and equal for all K radars.1-by-K vector –– The threshold requirement is specified for each radar and is assumed to be constant for all ranges in
range
.J-by-1 vector –– The threshold requirement is specified for each range in
range
and is assumed to be equal for all K radars.J-by-K matrix –– The threshold requirement is specified for each range in
range
and for each radar.
Data Types: double
Name-Value Arguments
Specify optional pairs of arguments as
Name1=Value1,...,NameN=ValueN
, where Name
is
the argument name and Value
is the corresponding value.
Name-value arguments must appear after other arguments, but the order of the
pairs does not matter.
Before R2021a, use commas to separate each name and value, and enclose
Name
in quotes.
Example: 'MaxRangeRequirement',125e3,'MetricName','Available SNR'
specifies the maximum range requirement to be 125000 m, and the metric name to be
'Available SNR'
MaxRangeRequirement
— Maximum range requirement
scalar | vector
Maximum range requirement, specified as one of the following:
scalar –– Specifies the objective requirement on the maximum range.
two-element vector –– Specifies both the objective and the threshold requirements in the [objective threshold] format.
Data Types: double
ShowStoplight
— Show stoplight chart
1
| 0
Specify whether to show the stoplight chart that color codes the area of the plot according to the specified requirements, specified as a logical scalar value.
If you only specify objective
, the function divides the area
of the plot into two colored zones along the metric axis. To satisfy the requirement,
the function by default assumes that the metric must be greater than or equal to the
objective. In this case, the area above objective
is marked
Pass
and is colored green, while the area below
objective
is marked Fail
and is colored
red.
To indicate the opposite case when the metric must be below the objective to
satisfy the requirement, specify the threshold
input explicitly
as Inf
. On the resultant stoplight chart, the objective requirement
is satisfied at the ranges where the metric
curve is in the
Pass
zone. At the ranges where the curve passes through the
Fail
zone, the system violates the objective requirement.
If you specify a finite threshold
, the area between
objective
and threshold
is colored yellow
and marked Warn
. At the ranges where the metric passes through the
Warn
zone, the objective requirement is violated, while the
threshold requirement is still satisfied. The stoplight chart can be displayed only
when the same requirements are specified for all radars
(objective
and threshold
are scalars or
length-J column vectors). Otherwise, this name-value pair is
ignored.
The value of the 'MaxRangeRequirement'
name-value pair limits
the Fail
and the Warn
zones along the range
axis. Both the Fail
and the Warn
zones extend to
the objective value of the maximum range requirement when only the objective is
provided. If both the objective and the threshold requirements are specified, the
Fail
zone extends to the threshold requirement while the
Warn
zone extends to the objective.
Data Types: logical
RadarName
— Names of radar systems
cell array of character vectors | string array
Names of the radar systems, specified as a length-K cell array
of character vectors or a string array, where K is the number of
radars. The radar names are used to augment the corresponding legend entries. When not
specified, the default name 'Radar
is
used for the kth radar system.k
'
Data Types: string
| char
| cell
MetricName
— Name of radar performance metric
character vector | string scalar
Name of radar performance metric, specified as a character vector or a string
scalar. When not specified, the default name 'Metric'
is
used.
Data Types: char
| string
RequirementName
— Name of requirement
character vector | string scalar
Name of requirement, specified as a character vector or a string scalar. When not
specified, the function uses the default name 'Requirement'
.
Data Types: char
| string
RangeUnit
— Units for range values
'm'
(default) | 'km'
| 'mi'
'nmi'
| 'ft'
Units for range values in vector range
and for the value of
'MaxRangeRequirement'
, specified as one of the following:
'm'
–– Meters'km'
–– Kilometers'mi'
–– Miles'nmi'
–– Nautical mile'ft'
–– Feet
MetricUnit
— Units for metric values
''
(default) | character vector | string scalar
Units for metric values, specified as a character vector or a string scalar.
Data Types: char
| string
Parent
— Plot axes
current axes (default) | Axes
object
Handle to plot axes, specified as an Axes
object. The default
value is the current axes, which can be specified using gca
.
Output Arguments
h
— Handle to axes in figure
Axes
object
Handle to the axes displayed in the figure, returned as an Axes
object.
More About
Stoplight Chart
A radar system must meet a set of performance requirements that depend on the environment and scenarios in which the system is intended to operate. A number of such requirements can be fairly large and a design that satisfies all of them might be impractical. In this case a tradeoff analysis is applied. A subset of the requirements is satisfied at the expense of accepting lower values for the rest of the metrics. Such tradeoff analysis can be facilitated by specifying multiple requirement values for a single metric.
The requirement for each metric is specified as a pair of values:
Objective — The desired level of the performance metric
Threshold — The value of the metric below which the system's performance is considered unsatisfactory
The region between the Threshold and the Objective values is the trade-space. It defines a margin by which a metric can be below the Objective value while the system is still considered to have a satisfactory performance.
A stoplight chart color-codes the status of the performance metric for a radar system based on the specified requirements. The plot is divided into three zones:
A Pass zone, colored green — At the ranges where the curve is in the Pass zone, the system performance satisfies the Objective value of the requirement.
A Warn zone, colored yellow — At the ranges where the curve passes through the Warn zone, the system performance violates the Objective value of the specified requirement but still satisfies the Threshold value.
A Fail zone, colored red — At the ranges where the curve passes through the Fail zone, the system performance violates the Threshold value of the specified requirement.
References
[1] Charles S. Wasson. System engineering analysis, design, and development: Concepts, principles, and practices. John Wiley & Sons, 2015.
Extended Capabilities
C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.
Version History
Introduced in R2021a
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