SpectrumAnalyzerBlockConfiguration
Configure Spectrum Analyzer for programmatic access
Description
The SpectrumAnalyzerBlockConfiguration
object contains the
scope configuration information for the Spectrum Analyzer block.
Creation
MyScopeConfiguration = get_param(gcbh,'ScopeConfiguration')
constructs a new spectrum analyzer configuration object. You must first select the block
in the model or provide the full path to the block.
Properties
Frequently Used
NumInputPorts
— Number of input ports
"1"
(default) | character vector | string scalar
Number of input ports on a scope block, specified as a character vector or string scalar. The maximum number of input ports that you can specify is 96.
Scope Window Use
This parameter is available only from the Property Inspector. To launch the Property Inspector, click the Modeling tab of the Simulink® model window that contains the Spectrum Analyzer block. In the Design section, click the drop-down arrow and select Property Inspector. The Property Inspector window opens on the right. If you select the Spectrum Analyzer block, the Property Inspector window shows the corresponding parameters. In the parameters that show up, specify the Number of input ports parameter.
Data Types: char
| string
SpectrumType
— Spectrum type
"Power"
(default) | "Power density"
| "RMS"
Spectrum type, specified as one of these:
"Power"
— Power spectrum
"Power density"
— Power spectral density. The power spectral
density is the magnitude squared of the spectrum normalized to a bandwidth of 1
Hz.
"RMS"
— Root mean square. The root mean square shows the square
root of the mean square. Use this option to view the frequency of voltage or current
signals.
Tunable: Yes
Scope Window Use
In the Scope tab on the Spectrum Analyzer toolstrip, select
Spectrum. Click Spectrum to select
Power
, Power Density
, or
RMS
.
Data Types: char
| string
SampleRateSource
— Source of input sample rate
"Inherited"
(default) | "Property"
Source of the input sample rate, specified as one of these:
"Inherited"
— Spectrum Analyzer inherits the input sample rate from the model."Property"
— Specify the sample rate input directly using theSampleRate
property.
Scope Window Use
Click the Scope tab on the Spectrum Analyzer toolstrip. In the
Bandwidth section, set Sample Rate
(Hz) to Inherited
or specify a finite
scalar.
Data Types: char
| string
SampleRate
— Sample rate of input
"10e3"
(default) | character vector of a positive scalar | string scalar of a positive scalar
Sample rate of the input signal in Hz, specified as a character vector or a string scalar of a positive scalar.
Dependency
To enable this property, set SampleRateSource
to "Property"
.
Scope Window Use
Click the Scope tab on the Spectrum Analyzer toolstrip. In the Bandwidth section, specify Sample Rate (Hz) to a finite scalar.
Data Types: char
| string
PlotAsTwoSidedSpectrum
— Option to plot a two-sided spectrum
false
(default) | true
Option to plot a two-sided spectrum, specified as one of the following:
false
— Compute and plot one-sided spectral estimates. If you set this property tofalse
, then the input signal must be real valued.When you set this property to
false
, the Spectrum Analyzer uses power-folding. The y-axis values are twice the amplitude that they would be if you were to set this property totrue
, except at0
and the Nyquist frequency. A one-sided power spectral density (PSD) contains the total power of the signal in the frequency interval from DC to half the Nyquist rate. For more information, seepwelch
(Signal Processing Toolbox).true
— Compute and plot two-sided spectral estimates. When the input signal is complex valued, you must set this property totrue
.
Scope Window Use
Click the Spectrum tab of the Spectrum Analyzer toolstrip. In the Trace Options section, select Two-Sided Spectrum to compute and plot two-sided spectral estimates.
Data Types: logical
FrequencyScale
— Scale to display frequency
"Linear"
(default) | "Log"
Scale to display frequency, specified as one of the following:
"Linear"
— Use a linear scale to display frequencies on the x-axis. To use the"Linear"
option, you must also set thePlotAsTwoSidedSpectrum
property totrue
."Log"
— Use a logarithmic scale to display frequencies on the x-axis. To use the"Log"
option, you must also set thePlotAsTwoSidedSpectrum
property tofalse
.
Tunable: Yes
Scope Window Use
Click the Spectrum tab on the Spectrum
Analyzer toolstrip. In the Scale section, set
the Frequency Scale to
Linear
or
Log
.
To set the Frequency Scale to
Log
, clear the Two-Sided
Spectrum check box in the Trace
Options section in the Spectrum
tab. If you select the Two-Sided Spectrum check
box, then you must set the Frequency Scale to
Linear
.
Data Types: char
| string
PlotType
— Plot type to display normal traces
"Line"
(default) | "Stem"
Plot type to display normal traces, specified as "Line"
or
"Stem"
. Normal traces are traces that display free-running
spectral estimates.
Tunable: Yes
Scope Window Use
Click the Scope tab on the Spectrum Analyzer toolstrip,
navigate to the Configuration section and click
Settings. In the Spectrum Analyzer Settings window, under
Display and Labels, set Plot Type to
Line
or Stem
.
Data Types: char
| string
AxesScaling
— Axes scaling mode
"Auto"
(default) | "Manual"
| "OnceAtStop"
| "Updates"
Axes scaling mode, specified as one of these:
"Auto"
— The scope scales the axes to fit the data, both during and after simulation."Manual"
— The scope does not scale the axes automatically."OnceAtStop"
— The scope scales the axes when the simulation stops."Updates"
— The scope scales the axes after a specific number of visual updates. It determines the number of updates using theAxesScalingNumUpdates
property.
Tunable: Yes
Data Types: char
| string
AxesScalingNumUpdates
— Number of updates before scaling
"100"
(default) | character vector of a positive integer | string scalar of a positive integer
Number of updates before scaling, specified as a character vector or a string scalar of a positive integer.
Tunable: Yes
Dependency
To enable this property, set AxesScaling
to
"Updates"
.
Data Types: char
| string
Advanced
RBWSource
— Source of resolution bandwidth value
"Auto"
(default) | "Property"
| "InputPort"
Source of the resolution bandwidth (RBW) value, specified as one of these:
"Auto"
— The Spectrum Analyzer adjusts the spectral estimation resolution to ensure that there are 1024 RBW intervals over the defined frequency span."Property"
— Specify the resolution bandwidth directly using theRBW
property."InputPort"
— An input port appears on the Spectrum Analyzer block through which you specify the RBW. You can use this option only for frequency inputs.
Tunable: Yes
Scope Window Use
Click the Estimation tab on the Spectrum Analyzer toolstrip. In the
Frequency Resolution section, set RBW
(Hz) to Auto
, Input
port
or to a positive scalar.
Data Types: char
| string
RBW
— Resolution bandwidth
"9.76"
(default) | character vector of a positive scalar | string scalar of a positive scalar
Resolution bandwidth (RBW) in Hz, specified as a character vector or a string scalar of a positive scalar. Specify the value to ensure that there are at least two RBW intervals over the specified frequency span. The ratio of the overall span to RBW satisfies this condition:
You can specify the overall span in different ways based on how you set the
FrequencySpan
property.
RBW controls the spectral resolution of the displayed signal. The RBW value determines the spacing between frequencies that can be resolved. A smaller value gives a higher spectral resolution and lowers the noise floor, that is, the Spectrum Analyzer can resolve frequencies that are closer to each other. However, this comes at the cost of a longer sweep time.
Tunable: Yes
Dependency
To enable this property, set RBWSource
to
"Property"
.
Scope Window Use
Click the Estimation tab on the Spectrum Analyzer toolstrip. In the Frequency Resolution section, set RBW (Hz) to a positive scalar.
Data Types: char
| string
OverlapPercent
— Overlap percentage
"0"
(default) | character vector of a real scalar in the range [0 100) | string scalar of a real scalar in the range [0 100)
Overlap percentage between the previous and current buffered data segments, specified as a character vector or string scalar of a real scalar in the range [0 100). The overlap creates a window segment that the Spectrum Analyzer uses to compute a spectral estimate.
Tunable: Yes
Scope Window Use
Click the Estimation tab on the Spectrum Analyzer toolstrip. In the Window Options section, set the Overlap (%).
Data Types: char
| string
Window
— Window function
"Hann"
(default) | "Rectangular"
Specify a window function for the spectral estimation. You can select one of the window options in the following table. For more information on the window functions, click the link to the function reference page in the Signal Processing Toolbox™ documentation.
Window Option | Corresponding Signal Processing Toolbox Function |
---|---|
"Rectangular" | rectwin (Signal Processing Toolbox) |
"Hann" | hann (Signal Processing Toolbox) |
Scope Window Use
Click the Estimation tab on the Spectrum Analyzer toolstrip. In the Window Options section, set the Window.
Data Types: char
| string
AveragingMethod
— Smoothing method
"Exponential"
(default) | "VBW"
Averaging method, specified as one of the following:
"Exponential"
— Weighted average of samples. The object computes the average over samples weighted by an exponentially decaying forgetting factor. Use theForgettingFactor
property to specify the weighted forgetting factor."VBW"
— Video bandwidth method. The object uses a lowpass filter to smooth the trace and decrease noise. Use theVBWSource
andVBW
properties to specify the VBW value.
For more information, see Averaging Method.
Tunable: Yes
Scope Window Use
Click the Estimation tab on the Spectrum
Analyzer toolstrip. In the Averaging section,
set Averaging Method to
VBW
or
Exponential
.
Data Types: char
| string
ForgettingFactor
— Weighting forgetting factor
"0.9"
(default) | string scalar of scalar in the range (0,1] | character vector of scalar in the range (0,1]
Forgetting factor of the exponential weighted averaging method, specified as a character vector or string scalar of a real scalar in the range (0,1].
Tunable: Yes
Dependency
To enable this property, set AveragingMethod
to "Exponential"
.
Scope Window Use
Click the Estimation tab on the Spectrum Analyzer toolstrip. In the Averaging section, adjust the Forgetting Factor slider.
To enable the Forgetting Factor, set
Averaging Method to
Exponential
.
Data Types: char
| string
VBWSource
— Source of video bandwidth
"Auto"
(default) | "Input port"
| "Property"
Source of the video bandwidth (VBW), specified as one of these:
"Auto"
— The Spectrum Analyzer adjusts the VBW such that the equivalent forgetting factor is 0.9."Input port"
–– An input port appears on the scope and you can specify the VBW value through this port."Property"
— The Spectrum Analyzer adjusts the VBW using the value specified in theVBW
property.
For more details on the video bandwidth method, see Averaging Method.
Tunable: Yes
Dependency
To enable this property, set AveragingMethod
to "VBW"
.
Scope Window Use
Click the Estimation tab on the Spectrum
Analyzer toolstrip. In the Averaging section,
set VBW (Hz) to either
Auto
or a positive real scalar less
than or equal to Sample Rate (Hz)/2.
To enable the VBW (Hz), set
Averaging Method to
VBW
.
Data Types: char
| string
VBW
— Video bandwidth
"9.76"
(default) | character vector of a positive scalar | string scalar of a positive scalar
Video bandwidth, specified as a character vector or a string scalar of
a positive scalar less than or equal to
SampleRate
/2. For more information on the video
bandwidth method, see Averaging Method.
Tunable: Yes
Dependency
To enable this property, set VBWSource
to
"Property"
.
Scope Window Use
Click the Estimation tab on the Spectrum
Analyzer toolstrip. In the Averaging section,
set VBW (Hz) to Auto
or enter a positive real scalar that is less than or equal to
Sample Rate (Hz)/2.
To enable the VBW (Hz), set
Averaging Method to
VBW
.
Data Types: double
SpectrumUnits
— Units of the spectrum
"dBm"
(default) | "dBm/Hz"
| "dBV"
| "dBuV"
(since R2023b) | "Vrms"
Units of the spectrum, specified as one of these:
"dBm"
"dBm/Hz"
"dBV"
"dBuV"
(since R2023b)"Vrms"
The Spectrum Analyzer displays power values in the units you select in this property.
Tunable: Yes
Dependency
The available spectrum units depend on the value you specify in
the SpectrumType
property.
SpectrumType | Allowed
SpectrumUnits |
---|---|
"Power" | "dBm" |
"Power density" | "dBm/Hz" |
"RMS" | "dBV" , "dBuV" (since R2023b),
"Vrms" |
Scope Window Use
Click the Spectrum tab on the Spectrum Analyzer toolstrip. In the Scale section, set Spectrum Unit.
Data Types: char
| string
ReferenceLoad
— Reference load to compute power levels
"1"
(default) | character vector of a real positive scalar | string scalar of a real positive scalar
Reference load to compute the power levels, specified as a character vector or a string scalar of a positive scalar in Ohms.
Tunable: Yes
Scope Window Use
Click the Spectrum tab on the Spectrum Analyzer toolstrip. In the Scale section, set Reference Load (Ω).
Data Types: char
| string
FrequencyOffset
— Frequency offset
"0"
(default) | numeric scalar character vector | numeric vector character vector | numeric scalar string scalar | numeric vector string scalar
Frequency offset, specified as one of these:
Numeric scalar — Apply the same frequency offset to all channels, specified as a character vector or a string scalar in Hz.
Numeric vector — Apply a specific frequency offset for each channel, specified as a character vector or a string scalar in Hz. The vector length must be equal to the number of input channels.
The frequency-axis values are offset by the values you specify in this property. The overall span must fall within the Nyquist Frequency Interval.
Tunable: Yes
Scope Window Use
Click the Scope tab on the Spectrum Analyzer toolstrip. In the Bandwidth section, set Offset (Hz).
Data Types: char
| string
TreatMby1SignalsAsOneChannel
— Option to treat unoriented input signal as a column vector
true
(default) | false
Option to treat unoriented input signal as a column vector, specified as
true
or false
. Set this property to
true
to treat M-by-1 and unoriented inputs as
a column vector or one channel. Set this property to false
to treat
M-by-1 and unoriented inputs as a 1-by-M row
vector.
Data Types: logical
Measurements
MeasurementChannel
— Channel for which to obtain measurements
"1"
(default) | character vector | string scalar
Channel over which the measurements are obtained, specified as a character vector or a string scalar which evaluates to a positive integer less than or equal to 100. The highest number you can specify is equal to the number of channels (columns) in the input signal.
Tunable: Yes
Scope Window Use
Click the Measurements tab on the Spectrum Analyzer toolstrip. In the Channel section, select a Channel.
Data Types: char
| string
CursorMeasurements
— Cursor measurements
CursorMeasurementsConfiguration
object
Cursor measurements, specified as a CursorMeasurementsConfiguration
object. Enable cursor measurements to display waveform cursors. All
CursorMeasurementsConfiguration
properties are
tunable.
Tunable: Yes
Scope Window Use
Click the Measurements tab on the Spectrum Analyzer toolstrip and modify the cursor measurements in the Cursors section.
DistortionMeasurements
— Distortion measurements
DistortionMeasurementsConfiguration
object
Distortion measurements, specified as a DistortionMeasurementsConfiguration
object. Enable distortion measurements
to compute and display the harmonic distortion and intermodulation distortion. All
DistortionMeasurementsConfiguration
properties are tunable.
Tunable: Yes
Scope Window Use
Click the Measurements tab on the Spectrum Analyzer toolstrip and modify the distortion measurements in the Distortion section.
PeakFinder
— Peak finder measurement
PeakFinderConfiguration
object
Peak finder measurement, specified as a PeakFinderConfiguration
object. Enable peak finder to compute and display
the largest calculated peak values. All PeakFinderConfiguration
properties are tunable.
Tunable: Yes
Scope Window Use
Click the Measurements tab on the Spectrum Analyzer toolstrip and modify the peak finder measurements in the Peaks section.
Visualization
Name
— Caption to display in spectrum Analyzer window
"Spectrum Analyzer"
(default) | character vector | string scalar
Caption to display in the scope window, specified as a character vector or string scalar.
Tunable: Yes
Data Types: char
| string
Position
— Window position
screen center (default) | [left bottom width height]
Spectrum Analyzer window position in pixels, specified by the size and location of the scope window as a four-element double vector of the form [left bottom width height]. You can place the scope window in a specific position on your screen by modifying the values to this property.
By default, the window appears in the center of your screen with a width of 800
pixels and height
of 450
pixels. The exact center coordinates depend on your screen resolution.
Tunable: Yes
MaximizeAxes
— Maximize axes control
"Auto"
(default) | "On"
| "Off"
Maximize axes control, specified as one of the following:
"Auto"
–– The Spectrum Analyzer maximizes axes only if the display does not contain any labels or title annotations."On"
–– The Spectrum Analyzer maximizes axes in all displays."Off"
–– The Spectrum Analyzer does not maximize axes in any display.
Tunable: Yes
Scope Window Use
Click the control on the Spectrum Analyzer display to
maximize the axes.
Data Types: char
| string
Title
— Display title
''
(default) | character vector | string scalar
Display title, specified as a character vector or a string scalar.
Tunable: Yes
Scope Window Use
Click the Scope tab on the spectrum analyzer toolstrip. In the Configuration section, click Settings. In the spectrum analyzer Settings window that opens up, under Display and labels, enter Title.
Data Types: char
| string
YLabel
— Y-axis label
''
(default) | character vector | string scalar
y-axis label, specified as a character vector or a string scalar. The Spectrum Analyzer displays the label to the left of the y-axis.
Regardless of the value of this property, Spectrum Analyzer always displays power
units as one of the SpectrumUnits
values.
Tunable: Yes
Scope Window Use
Click the Scope tab on the Spectrum Analyzer toolstrip. In the Configuration section, click Settings. In the Spectrum Analyzer Settings window that opens up, under Display and labels, enter Y-Label.
Data Types: char
| string
YLimits
— Y-axis limits
[-80, 20]
(default) | [ymin ymax]
y-axis limits, specified as a two-element numeric vector of the
form [ymin ymax
]. The units of the y-axis limits
depend on the SpectrumUnits
property.
Example: scope.YLimits = [-10,20]
Tunable: Yes
Scope Window Use
Click the Scope tab on the Spectrum Analyzer toolstrip. In the Configuration section, click Settings. In the Spectrum Analyzer Settings window that opens up, under Display and Labels, enter Y-Axis Limits.
ShowGrid
— Flag to show grid
true
(default) | false
Flag to show the grid, specified as true
or
false
. Set this property to true
to show grid
lines in the plot.
Tunable: Yes
Scope Window Use
Click the Scope tab on the Spectrum Analyzer toolstrip. In the Configuration section, click Settings. In the Spectrum Analyzer Settings window that appears, under Display and Labels, select Show Grid.
Data Types: logical
ChannelNames
— Channel names
empty cell (default) | cell array of character vectors | array of strings
Channel names in the input data, specified as a cell array of character vectors or an array of strings. The names you specify in this property appear in the following locations:
Legend
Spectrum Analyzer Settings > Color and styling section
Measurements and Channel Measurements tabs
If you do not specify channel names, the
spectrum analyzer names the channels as Channel 1
, Channel
2
, and so on.
Tunable: Yes
Dependency
To see the channel names, set ShowLegend
to
true
.
Scope Window Use
Click the Scope tab on the spectrum analyzer toolstrip. To see the legend, click Legend in the Configuration section.
Data Types: char
ShowLegend
— Flag to show legend
false
(default) | true
Flag to show the legend, specified as true
or
false
. To show a legend with the input names, set this property
to true
.
Use the legend to control which signals are visible. In the scope legend, click a signal name to hide the signal in the scope. To show the signal, click the signal name again. To show only one signal, right-click the signal name. To show all signals, press Esc.
Tunable: Yes
Scope Window Use
Click the Scope tab on the Spectrum Analyzer toolstrip. To see the legend, click Legend in the Configuration section.
Data Types: logical
OpenAtSimulationStart
— Flag to open scope when simulation starts
true
(default) | false
Flag to open scope when simulation starts, specified as true
or
false
.
Set this property to true
to open the scope when the simulation starts.
Set this property to false
to prevent the scope from opening when you
simulate the model.
Scope Window Use
This parameter is available only from the Property Inspector. To launch the Property Inspector, click the Modeling tab of the Simulink model window that contains the Spectrum Analyzer block. In the Design section, click the drop-down arrow and select Property Inspector. The Property Inspector window opens on the right. If you select the Spectrum Analyzer block, the Property Inspector window shows the corresponding parameters. In the parameters that show up, select or clear the Open at simulation start parameter.
Data Types: logical
Visible
— Visibility of the Spectrum Analyzer
false
(default) | true
Set this property to true
to display the spectrum analyzer window, and to
false
to hide the spectrum analyzer window.
Data Types: logical
Examples
Construct Spectrum Analyzer Configuration Object
Create the configuration object for a Spectrum Analyzer block.
Create a new Simulink® model with a randomly generated name.
sysname=char(randi(26,1,7)+96); new_system(sysname);
Add a new Spectrum Analyzer block to the model.
add_block('built-in/SpectrumAnalyzer',[sysname,'/SpectrumAnalyzer'])
Call the get_param
function to retrieve the default
Spectrum Analyzer block configuration properties.
config = get_param([sysname,'/SpectrumAnalyzer'],'ScopeConfiguration')
config = SpectrumAnalyzerBlockConfiguration with properties: NumInputPorts: '1' SpectrumType: 'Power' SampleRateSource: 'Inherited' PlotAsTwoSidedSpectrum: 1 FrequencyScale: 'Linear' PlotType: 'Line' AxesScaling: 'Auto' Advanced RBWSource: 'Auto' AveragingMethod: 'VBW' VBWSource: 'Auto' SpectrumUnits: 'dBm' ReferenceLoad: '1' FrequencyOffset: '0' TreatMby1SignalsAsOneChannel: 1 Spectrogram No properties. Measurements MeasurementChannel: '1' CursorMeasurements: [1×1 CursorMeasurementsConfiguration] DistortionMeasurements: [1×1 DistortionMeasurementsConfiguration] PeakFinder: [1×1 PeakFinderConfiguration] Visualization Name: 'SpectrumAnalyzer' Position: [880 470 800 500] MaximizeAxes: 'Auto' Title: '' YLabel: '' YLimits: [-80 20] ShowGrid: 1 ChannelNames: {''} ShowLegend: 0 OpenAtSimulationStart: 1 Visible: 0
Version History
Introduced in R2016bR2023b: Spectrum Analyzer supports dBuV
units
You can set SpectrumUnits
to "dBuV"
when
you set SpectrumType
to "RMS"
.
R2023a: Spectrum Analyzer with better responsiveness and toolstrip interface in Simulink
In R2023a, the Spectrum Analyzer block comes with better responsiveness and a toolstrip interface that gives you easy access to spectral analysis, estimation, and measurements.
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