SpectrumAnalyzerConfiguration
Configure Spectrum Analyzer block
Description
The spbscopes.SpectrumAnalyzerConfiguration
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 give 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 by a character vector or string scalar. Maximum number of input ports is 96.
Data Types: char
| string
InputDomain
— Domain of the input signal
"Time"
(default) | "Frequency"
The domain of the input signal you want to visualize. If you visualize time-domain
signals, the signal is transformed to the frequency spectrum based on the algorithm
specified by the Method
parameter.
Scope Window Use
Open the Spectrum Settings. In the Main options section, set Input Domain.
Data Types: char
| string
SpectrumType
— Type of spectrum to show
"Power"
(default) | "Power density"
| "RMS"
Specify the spectrum type to display.
"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
hertz.
"RMS"
— Root mean square. The root-mean-square shows the square
root of the mean square. This option is useful when viewing the frequency of voltage or
current signals.
Tunable: Yes
Scope Window Use
Open the Spectrum Settings. In the Main options section, set Type.
Data Types: char
| string
ViewType
— Viewer type
"Spectrum"
(default) | "Spectrogram"
| "Spectrum and spectrogram"
Specify the spectrum type as one of "Spectrum"
,
"Spectrogram"
, or "Spectrum and spectrogram"
.
"Spectrum"
— shows the power spectrum."Spectrogram"
— shows frequency content over time. Each line of the spectrogram is one periodogram. Time scrolls from the bottom to the top of the display. The most recent spectrogram update is at the bottom of the display."Spectrum and Spectrogram"
— shows a dual view of a spectrum and spectrogram.
Tunable: Yes
Scope Window Use
Open the Spectrum Settings. In the Main options section, set View.
Data Types: char
| string
SampleRateSource
— Source of input sample rate
"Inherited"
(default) | "Property"
Specify the source of the input sample rate as:
"Inherited"
— Spectrum Analyzer inherits the input sample rate from the model."Property"
— Specify the sample rate input directly using theSampleRate
property.
Data Types: char
| string
SampleRate
— Sample rate of input
"10e3"
(default) | character vector | string scalar
Specify the sample rate of the input signals in hertz as a character vector or string scalar.
Dependency
To enable this property, set SampleRateSource
to "Property"
.
Data Types: char
| string
Method
— Spectrum estimation method
"Welch"
(default) | "Filter Bank"
Specify the spectrum estimation method as Welch
or Filter
bank
.
Dependency
To enable this property, set InputDomain
to
"Time"
.
Scope Window Use
Open the Spectrum Settings. In the Main options section, set Method.
Data Types: char
| string
PlotAsTwoSidedSpectrum
— Two-sided spectrum flag
true
(default) | false
true
— Compute and plot two-sided spectral estimates. When the input signal is complex-valued, you must set this property totrue
.false
— Compute and plot one-sided spectral estimates. If you set this property tofalse
, then the input signal must be real-valued.When this property is
false
, Spectrum Analyzer uses power-folding. The y-axis values are twice the amplitude that they would be if this property were set 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 of the Nyquist rate. For more information, seepwelch
.
Scope Window Use
Open the Spectrum Settings. In the Trace options section, select Two-sided spectrum.
Data Types: logical
FrequencyScale
— Frequency scale
"Linear"
(default) | "Log"
"Log"
— displays the frequencies on the x-axis on a logarithmic scale. To use the"Log"
setting, you must also set thePlotAsTwoSidedSpectrum
property tofalse
."Linear"
— displays the frequencies on the x-axis on a linear scale. To use the"Linear"
setting, you must also set thePlotAsTwoSidedSpectrum
property totrue
.
Tunable: Yes
Scope Window Use
Open the Spectrum Settings. In the Trace options section, set Scale.
Data Types: char
| string
Advanced
FrequencySpan
— Frequency span mode
"Full"
(default) | "Span and center frequency"
| "Start and stop frequencies"
"Full"
- The Spectrum Analyzer computes and plots the spectrum over the entire Nyquist frequency interval."Span and center frequency"
- The Spectrum Analyzer computes and plots the spectrum over the interval specified by theSpan
andCenterFrequency
properties."Start and stop frequencies"
- The Spectrum Analyzer computes and plots the spectrum over the interval specified by theStartFrequency
andStopFrequency
properties.
Tunable: Yes
Scope Window Use
Open the Spectrum Settings. In the Main
options section, select Full frequency span for
"Full"
. Otherwise, clear the Full frequency
span check box and choose between Span
or
FStart
.
Data Types: char
| string
Span
— Frequency span to compute spectrum
"10e3"
(default) | character vector of a real positive scalar | string scalar of a real positive scalar
Specify (as a character vector or string scalar) the frequency span,
in hertz, over which the Spectrum Analyzer computes and plots the
spectrum. The overall span, defined by this property and the
CenterFrequency
property, must fall within the
Nyquist frequency interval.
Dependency
To enable this property, set FrequencySpan
to
"Span and center frequency"
.
Data Types: char
| string
CenterFrequency
— Center of frequency span
"0"
(default) | character vector of a real scalar | string scalar of a real scalar
Specify (as a character vector or string scalar) the frequency center,
in hertz, over which the Spectrum Analyzer computes and plots the
spectrum. The overall frequency span, defined by the
Span
and this property, must fall within the
Nyquist frequency interval.
Dependency
To enable this property, set FrequencySpan
to
"Span and center frequency"
.
Data Types: char
| string
StartFrequency
— Start frequency to compute spectrum
"-5e3"
(default) | character vector of a real scalar | string scalar of a real scalar
Start of the frequency interval over which spectrum is computed,
specified in hertz as a character vector or string scalar of a real
scalar. The overall span, which is defined by this property and
StopFrequency
, must fall within the Nyquist frequency interval.
Dependency
To enable this property, set FrequencySpan
to
"Start and stop frequencies"
.
Data Types: char
| string
StopFrequency
— Stop frequency to compute spectrum
"5e3"
(default) | character vector of a real scalar | string scalar of a real scalar
End of the frequency interval over which spectrum is computed,
specified in hertz as a character vector or string scalar of a real
scalar. The overall span, which is defined by this property and the
StartFrequency
property, must fall within the
Nyquist frequency interval.
Dependency
To enable this property, set FrequencySpan
to
"Start and stop frequencies"
.
Scope Window Use
Open the Spectrum Settings. In the
Main options section, clear the
Full frequency span and change
Span
to
FStart
. Set FStop
(Hz).
Data Types: char
| string
FrequencyResolutionMethod
— Frequency resolution method
"RBW"
(default) | "WindowLength"
| "NumFrequencyBands"
Specify the frequency resolution method of the Spectrum Analyzer.
"RBW"
- TheRBWSource
andRBW
properties control the frequency resolution (in Hz) of the analyzer. The FFT length is the window length that results from achieving the specified RBW value or 1024, whichever is larger."WindowLength"
- Applies only when theMethod
property is set to"Welch"
. TheWindowLength
property controls the frequency resolution. You can control the number of FFT points only when theFrequencyResolutionMethod
property is"WindowLength"
."NumFrequencyBands"
- Applies only when theMethod
property is set to"Filter Bank"
. TheFFTLengthSource
andFFTLength
properties control the frequency resolution.
Tunable: Yes
Dependency
To enable this property, set InputDomain
to
"Time"
.
Scope Window Use
Open the Spectrum Settings. In the Main options section, set the frequency resolution method by selecting the RBW (Hz) dropdown.
Data Types: char
| string
RBWSource
— Source of resolution bandwidth value
"Auto"
(default) | "Property"
| "InputPort"
Specify the source of the resolution bandwidth (RBW) as
"Auto"
, "Property"
, or
"InputPort"
.
"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 is added to the Spectrum Analyzer block to read the RBW. This option is only applicable to frequency input.
Dependencies
To enable this property, set:
InputDomain
to"Time"
andFrequencyResolutionMethod
to"RBW"
.InputDomain
to"Frequency"
.
Data Types: char
| string
RBW
— Resolution bandwidth
"9.76"
(default) | character vector | string scalar
RBW controls the spectral resolution of the Spectrum Analyzer. Specify the resolution bandwidth in hertz as a character vector or string scalar. You must specify a value to ensure that there are at least two RBW intervals over the specified frequency span. Thus, the ratio of the overall span to RBW must be greater than two:
You can specify the overall span in different ways based on how you
set the FrequencySpan
property.
Dependency
To enable, set:
RBWSource
to"Property"
Data Types: char
| string
WindowLength
— Window length
"1024"
(default) | character vector of an integer greater than 2 | string scalar of an integer greater than 2
Control the frequency resolution by specifying the window length in samples used to compute the spectral estimates. The window length must be an integer scalar greater than 2, specified as a character vector or string scalar.
Dependencies
To enable this property, set:
FrequencyResolutionMethod
to"WindowLength"
, which controls the frequency resolution based on your window length setting.Method
to"Welch"
.
Data Types: char
| string
FFTLengthSource
— Source of the FFT length
"Auto"
(default) | "Property"
"Auto"
- sets the FFT length to the window length specified in theWindowLength
property or 1024, whichever is larger."Property"
- number of FFT points using theFFTLength
property.FFTLength
must be greater thanWindowLength
.
Tunable: Yes
Dependency
To enable this property, set FrequencyResolutionMethod
to
"WindowLength"
.
Scope Window Use
Open the Spectrum Settings. In the Main options section, next to the RBW (Hz) option, enter
a number or select Auto
.
Data Types: char
| string
FFTLength
— Length of FFT
"1024"
(default) | character vector | string scalar
Specify the length of the FFT that the Spectrum Analyzer uses to compute spectral estimates.
If FrequencyResolutionMethod
is
"RBW"
, the FFT length is set as the window length
required to achieve the specified resolution bandwidth value or 1024,
whichever is larger.
Dependencies
To use this property, the following must be true:
FFTLength
value is greater than or equal to theWindowLength
.FrequencyResolutionMethod
is set to"WindowLength"
or"NumFrequencyBands"
FFTLengthSource
is set to"Property"
.
Data Types: char
| string
NumTapsPerBand
— Number of filter taps per frequency band
"12"
(default) | character vector of even integer | string scalar of even integer
Specify the number of filter taps or coefficients for each frequency
band as a character vector or a string scalar. This number must be a
positive even integer. This value corresponds to the number of filter
coefficients per polyphase branch. The total number of filter
coefficients is equal to NumTapsPerBand
+
FFTLength
.
Dependency
To enable this property, set Method
to
"Filter Bank"
.
Data Types: char
| string
FrequencyVectorSource
— Source of frequency vector
"Auto"
(default) | "Property"
| "InputPort"
"Auto"
— The frequency vector is calculated from the length of the input. See Frequency Vector."Property"
— Enter a custom vector as the frequency vector."InputPort"
— An input port appears on the block to read the frequency vector input.
Dependency
To enable this property, set InputDomain
to
"Frequency"
.
Data Types: char
| string
FrequencyVector
— Custom frequency vector
[-5000 5000]
(default) | monotonically increasing vector
Set the frequency vector that determines the x-axis of the display. The vector must be monotonically increasing and of the same size as the input frame size.
Dependency
To enable this property, set FrequencyVectorSource
to
"Property"
.
Scope Window Use
Open the Spectrum Settings. In the Frequency input options section, set Frequency (Hz).
Data Types: single
| double
| int8
| int16
| int32
| int64
| uint8
| uint16
| uint32
| uint64
InputUnits
— Units of frequency input
"dBm"
(default) | "dBV"
| "dBW"
| "Vrms"
| "Watts"
Select the units of the frequency-domain input. This property allows the Spectrum
Analyzer to scale frequency data if you choose a different display unit with the
Units
property.
Dependency
This option is only available when InputDomain
is set to
Frequency
.
Scope Window Use
Open the Spectrum Settings. In the Frequency input options section, set Input units.
Data Types: char
| string
OverlapPercent
— Overlap percentage
"0"
(default) | character vector of a real scalar | string scalar of a real scalar
The percentage overlap between the previous and current buffered data segments, specified as a character vector or string scalar of a real scalar. The overlap creates a window segment that is used to compute a spectral estimate. The value must be greater than or equal to zero and less than 100.
Data Types: char
| string
Window
— Window function
"Hann"
(default) | "Rectangular"
| "Chebyshev"
| "Flat Top"
| "Hamming"
| "Kaiser"
| "Blackman-Harris"
| "Custom"
Specify a window function for the spectral estimator. The following table shows preset windows. For more information, follow the link to the corresponding function reference in the Signal Processing Toolbox™ documentation.
Window Option | Corresponding Signal Processing Toolbox Function |
---|---|
"Rectangular" | rectwin |
"Chebyshev" | chebwin |
"Flat Top" | flattopwin |
"Hamming" | hamming |
"Hann" | hann |
"Kaiser" | kaiser |
"Blackman-Harris" | blackmanharris |
To set your own spectral estimation window, set this property to
"Custom"
and specify a custom window function in the
CustomWindow
property.
Tunable: Yes
Scope Window Use
Open the Spectrum Settings. In the Window options section, set Window.
Data Types: char
| string
CustomWindow
— Custom window function
"hann"
(default) | character array | string scalar
Specify a custom window function as a character array or string. The custom window function name must be on the MATLAB path. This property is useful if you want to customize the window using additional properties available with the Signal Processing Toolbox version of the window function.
Tunable: Yes
Example
Define and use a custom window function.
function w = my_hann(L) w = hann(L, 'periodic') end scope.Window = 'Custom'; scope.CustomWindow = 'my_hann'
Dependency
To use this property, set Window
to
"Custom"
.
Scope Window Use
Open the Spectrum Settings. In the Window options section, in the Window option box, enter a custom window function name.
Data Types: char
| string
SidelobeAttenuation
— Sidelobe attenuation of window
"60"
(default) | character vector of real positive scalar | string scalar of real positive scalar
The window sidelobe attenuation, in decibels (dB). The value must be greater than or equal to 45.
Dependency
To enable this property, set Window
to
"Chebyshev"
or "Kaiser"
.
Scope Window Use
Open the Spectrum Settings. In the Window options section, set Attenuation (dB).
Data Types: char
| string
SpectrumUnits
— Units of the spectrum
"Auto"
(default) | "dBm"
| "dBFS"
| "dBV"
| "dBW"
| "Vrms"
| "Watts"
Specify the units in which the Spectrum Analyzer displays power values.
Tunable: Yes
Dependency
The available spectrum units depend on the value of
SpectrumType
.
InputDomain | SpectrumType | Allowed
SpectrumUnits |
---|---|---|
Time | Power or Power
density | "dBFS" , "dBm" ,
"dBW" , "Watts" |
RMS | "Vrms" , "dBV" | |
Frequency | ― | "dBm" , "dBV" ,
"dBW" , "Vrms" ,
"Watts" , |
Scope Window Use
Open the Spectrum Settings. In the Trace options section, set Units.
Data Types: char
| string
FullScaleSource
— Source of full scale
"Auto"
(default) | "Property"
Specify the source of the dBFS scaling factor as either "Auto"
or
"Property"
.
"Auto"
- The Spectrum Analyzer adjusts the scaling factor based on the input data."Property"
- Specify the full-scale scaling factor using theFullScale
property.
Dependency
To enable this property, set SpectrumUnits
to
"dBFS"
.
Scope Window Use
Open the Spectrum Settings. In the Trace
options section, set Full scale to
Auto
or enter a number.
Data Types: char
| string
FullScale
— Full scale
"1"
(default) | character vector of a positive scalar | string scalar of a positive scalar
Specify a character vector or string scalar of a real positive scalar
for the dBFS
full scale.
Dependency
To enable this option set:
SpectrumUnits
to"dBFS"
FullScaleSource
to"Property"
Data Types: char
| string
AveragingMethod
— Smoothing method
"Running"
(default) | "Exponential"
Specify the smoothing method as:
Running
— Running average of the last n samples. Use theSpectralAverages
property to specify n.Exponential
— Weighted average of samples. Use theForgettingFactor
property to specify the weighted forgetting factor.
For more information about the averaging methods, see Averaging Method.
Dependency
To enable this property, set ViewType
to
"Spectrum"
or "Spectrum and
spectrogram"
.
Scope Window Use
Open the Spectrum Settings. In the Trace options section, set Averaging method.
Data Types: char
| string
SpectralAverages
— Number of spectral averages
"1"
(default) | character vector | string scalar
Specify the number of spectral averages as a character vector or string scalar. The Spectrum Analyzer computes the current power spectrum estimate by computing a running average of the last N power spectrum estimates. This property defines N.
Dependency
To enable this property, set AveragingMethod
to
"Running"
.
Scope Window Use
Open the Spectrum Settings. In the Trace options section, set Averages.
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]
Specify the exponential weighting as a scalar value greater than 0 and less than or equal to 1, specified as a string scalar or character vector.
Dependency
To enable this property, set AveragingMethod
to
"Exponential"
.
Scope Window Use
Open the Spectrum Settings. In the Trace options section, set Forgetting factor.
Data Types: char
| string
ReferenceLoad
— Reference load
"1"
(default) | character vector of a real positive scalar | string scalar of a real positive scalar
Specify the load the scope uses as a reference to compute power levels.
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
Numeric scalar (specified as a character vector or string scalar) — Apply the same frequency offset to all channels, specified in hertz as a character vector.
Numeric vector (specified as a character vector or string scalar) — Apply a specific frequency offset for each channel, specify a vector of frequencies. The vector length must be equal to number of input channels.
The frequency-axis values are offset by the values specified in this property. The overall span must fall within the Nyquist frequency interval. You can control the overall span in different ways based on how you set the
FrequencySpan
property.
Data Types: char
| string
TreatMby1SignalsAsOneChannel
— Treat unoriented sample-based input signal as a column vector
true
(default) | false
Set this property to true
to treat
M-by-1 and unoriented sample-based inputs as a
column vector, or one channel. Set this property to
false
to treat M-by-1 and
unoriented sample-based inputs as a 1-by-M row
vector.
Data Types: logical
Spectrogram
SpectrogramChannel
— Channel for which spectrogram is plotted
"1"
(default) | character vector of a positive scalar integer | string scalar of a positive scalar integer
Specify the channel for which the spectrogram is plotted, as a character vector or string scalar of a real, positive scalar integer in the range [1 N], where N is the number of input channels.
Dependency
To enable this property, set ViewType
to
"Spectrogram"
or "Spectrum and
spectrogram"
.
Data Types: char
| string
TimeResolutionSource
— Source of the time resolution value
"Auto"
(default) | "Property"
Specify the source for the time resolution of each spectrogram line as either
"Auto"
or "Property"
. The
TimeResolution
property shows the time resolution for the
different frequency resolution methods and time resolution properties.
Tunable: Yes
Dependency
To enable this property, set ViewType
to
"Spectrogram"
or "Spectrum and
spectrogram"
.
Scope Window Use
Open the Spectrum Settings. In the Spectrogram options section, set Time res (s).
Data Types: char
| string
TimeResolution
— Time resolution
"1e-3"
(default) | character vector of a positive scalar | string scalar of a positive scalar
Specify the time resolution of each spectrogram line as a character vector or string scalar of a positive scalar, expressed in seconds.
The time resolution value is determined based on frequency resolution method, the RBW setting, and the time resolution setting.
Method | Frequency Resolution Method | Frequency Resolution Setting | Time Resolution Setting | Resulting Time Resolution in Seconds |
---|---|---|---|---|
Welch or Filter
Bank | RBW (Hz) | Auto | Auto | 1/RBW |
Welch or Filter
Bank | RBW (Hz) | Auto | Manually entered | Time Resolution |
Welch or Filter
Bank | RBW (Hz) | Manually entered | Auto | 1/RBW |
Welch or Filter
Bank | RBW (Hz) | Manually entered | Manually entered | Must be equal to or greater than the minimum attainable time resolution, 1/RBW. Several spectral estimates are combined into one spectrogram line to obtain the desired time resolution. Interpolation is used to obtain time resolution values that are not integer multiples of 1/RBW. |
Welch | Window length | — | Auto | 1/RBW |
Welch | Window length | — | Manually entered | Must be equal to or greater than the minimum attainable time resolution. Several spectral estimates are combined into one spectrogram line to obtain the desired time resolution. Interpolation is used to obtain time resolution values that are not integer multiples of 1/RBW. |
Filter Bank | Number of frequency bands | — | Auto | 1/RBW |
Filter Bank | Number of frequency bands | — | Manually entered | Must be equal to or greater than the minimum attainable time resolution, 1/RBW. |
Dependency
To enable this property, set:
ViewType
to"Spectrogram"
or"Spectrum and spectrogram"
TimeResolutionSource
to"Property
.
Data Types: char
| string
TimeSpanSource
— Source of time span value
"Auto"
(default) | "Property"
Specify the source for the time span of the spectrogram as either
"Auto"
or "Property"
. If you set this property
to "Auto"
, the spectrogram displays 100 spectrogram lines at any
given time. If you set this property to "Property"
, the spectrogram
uses the time duration you specify in seconds in the TimeSpan
property.
Tunable: Yes
Dependency
To enable this property, set ViewType
to
"Spectrogram"
or "Spectrum and
spectrogram"
.
Scope Window Use
Open the Spectrum Settings. In the Spectrogram options section, set Time span (s).
Data Types: char
| string
TimeSpan
— Time span
"0.1"
(default) | character vector of a positive scalar | string scalar of a positive scalar
Specify the time span of the spectrogram display in seconds. You must set the time span to be at least twice as large as the duration of the number of samples required for a spectral update.
Dependency
To enable this property, set:
ViewType
to"Spectrogram"
or"Spectrum and spectrogram"
.TimeSpanSource
to"Property"
.
Data Types: char
| string
Measurements
MeasurementChannel
— Channel for which measurements are obtained
"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 greater than 0 and less than or equal to 100. The maximum number you can specify is the number of channels (columns) in the input signal.
Tunable: Yes
Data Types: char
| string
SpectralMask
— Spectral mask lines
SpectralMaskSpecification
object
Specify whether to display upper and lower spectral mask lines on a spectrum plot.
This property uses properties from a SpectralMaskSpecification
object to enable and configure the spectral
masks.
Tunable: Yes
Scope Window Use
Open the Spectral Mask pane and modify the Settings options.
PeakFinder
— Peak finder measurement
PeakFinderSpecification
object
Enable peak finder to compute and display the largest calculated peak values. The PeakFinder
property uses the PeakFinderSpecification
properties.
The PeakFinderSpecification
properties are:
MinHeight
–– Level above which peaks are detected, specified as a scalar value.Default:
-Inf
NumPeaks
–– Maximum number of peaks to show, specified as a positive integer scalar less than 100.Default:
3
MinDistance
–– Minimum number of samples between adjacent peaks, specified as a positive real scalar.Default:
1
Threshold
–– Minimum height difference between peak and its neighboring samples, specified as a nonnegative real scalar.Default:
0
LabelFormat
–– Coordinates to display next to the calculated peak value, specified as a character vector or a string scalar. Valid values are"X"
,"Y"
, or"X + Y"
.Default:
"X + Y"
Enable
–– Set this property totrue
to enable peak finder measurements. Valid values aretrue
orfalse
.Default:
false
All PeakFinderSpecification
properties are tunable.
Tunable: Yes
Scope Window Use
Open the Peak Finder pane () and modify the Settings
options.
CursorMeasurements
— Cursor measurements
CursorMeasurementsSpecification
object
Enable cursor measurements to display screen or waveform cursors. The CursorMeasurements
property uses the CursorMeasurementsSpecification
properties.
The CursorMeasurementsSpecification
properties are:
Type
–– Type of the display cursors, specified as either"Screen cursors"
or"Waveform cursors"
.Default:
"Waveform cursors"
ShowHorizontal
–– Set this property totrue
to show the horizontal screen cursors. This property applies when you set theType
property to"Screen cursors"
.Default:
true
ShowVertical
–– Set this property totrue
to show the vertical screen cursors. This property applies when you set theType
property to"Screen cursors"
.Default:
true
Cursor1TraceSource
–– Specify the waveform cursor 1 source as a positive real scalar. This property applies when you set theType
property to"Waveform cursors"
.Default:
1
Cursor2TraceSource
–– Specify the waveform cursor 2 source as a positive real scalar. This property applies when you set theType
property to"Waveform cursors"
.Default:
1
LockSpacing
–– Lock spacing between cursors, specified as a logical scalar.Default:
false
SnapToData
–– Snap cursors to data, specified as a logical scalar.Default:
true
XLocation
–– x-coordinates of the cursors, specified as a real vector of length equal to 2.Default:
[-2500 2500]
YLocation
–– y-coordinates of the cursors, specified as a real vector of length equal to 2. This property applies when you set theType
property to"Screen cursors"
.Default:
[-55 5]
Enable
–– Set this property totrue
to enable cursor measurements. Valid values aretrue
orfalse
.Default:
false
All CursorMeasurementsSpecification
properties are tunable.
Scope Window Use
Open the Cursor Measurements pane () and modify the Settings
options.
ChannelMeasurements
— Channel measurements
ChannelMeasurementsSpecification
object
Enable channel measurements to compute and display the occupied bandwidth or adjacent channel power ratio. The ChannelMeasurements
property uses the ChannelMeasurementsSpecification
properties.
The ChannelMeasurementsSpecification
properties are:
Algorithm
–– Type of measurement data to display, specified as either"Occupied BW"
or"ACPR"
.Default:
"Occupied BW"
FrequencySpan
–– Frequency span mode, specified as either"Span and center frequency"
or"Start and stop frequencies"
Default:
"Span and center frequency"
Span
–– Frequency span over which the channel measurements are computed, specified as a real, positive scalar in Hz. This property applies when you set theFrequencySpan
property to"Span and center frequency"
.Default:
2000
HzCenterFrequency
–– Center frequency of the span over which the channel measurements are computed, specified as a real scalar in Hz. This property applies when you set theFrequencySpan
property to"Span and center frequency"
.Default:
0
HzStartFrequency
–– Start frequency over which the channel measurements are computed, specified as a real scalar in Hz. This property applies when you set theFrequencySpan
property to"Start and stop frequencies"
.Default:
-1000
HzStopFrequency
–– Stop frequency over which the channel measurements are computed, specified as a real scalar in Hz. This property applies when you set theFrequencySpan
property to"Start and stop frequencies"
.Default:
1000
HzPercentOccupiedBW
–– Percent of power over which to compute the occupied bandwidth, specified as a positive real scalar. This property applies when you set theAlgorithm
property to"Occupied BW"
.Default:
99
NumOffsets
–– Number of adjacent channel pairs, specified as a real, positive integer. This property applies when you set theAlgorithm
property to"ACPR"
.Default:
2
AdjacentBW
–– Adjacent channel bandwidth, specified as a real, positive scalar. This property applies when you set theAlgorithm
property to"ACPR"
.Default:
1000
FilterShape
–– Filter shape for both main and adjacent channels, specified as"None"
,"Gaussian"
, or"RRC"
. This property applies when you set theAlgorithm
property to"ACPR"
.Default:
"None"
FilterCoeff
–– Channel filter coefficient, specified as a real scalar between0
and1
. This property applies when you set theAlgorithm
property to"ACPR"
and theFilterShape
property to either"Gaussian"
or"RRC"
.Default:
0.5
ACPROffsets
–– Frequency of the adjacent channel relative to the center frequency of the main channel, specified as a real vector of length equal to the number of offset pairs specified inNumOffsets
. This property applies when you set theAlgorithm
property to"ACPR"
.Default:
[2000 3500]
Enable
–– Set this property totrue
to enable channel measurements. Valid values aretrue
orfalse
.Default:
false
All ChannelMeasurementsSpecification
properties are tunable.
Scope Window Use
Open the Channel Measurements pane () and modify the Measurement
and Channel Settings options.
DistortionMeasurements
— Distortion measurements
DistortionMeasurementsSpecification
object
Enable distortion measurements to compute and display the harmonic distortion and intermodulation distortion. The DistortionMeasurements
property uses the DistortionMeasurementsSpecification
properties.
The DistortionMeasurementsSpecification
properties are:
Algorithm
–– Type of measurement data to display, specified as either"Harmonic"
or"Intermodulation"
.Default:
"Harmonic"
NumHarmonics
–– Number of harmonics to measure, specified as a real, positive integer. This property applies when you set theAlgorithm
to"Harmonic"
.Default:
6
Enable
–– Set this property totrue
to enable distortion measurements.Default:
false
All DistortionMeasurementsSpecification
properties are tunable.
Scope Window Use
Open the Distortion Measurements pane () and modify the Distortion
and Harmonics options.
CCDFMeasurements
— CCDF measurements
CCDFMeasurementsSpecification
object
Enable CCDF measurements to display the probability of the input signal's instantaneous power
being a certain amount of dB above the signal's average power. The
CCDFMeasurements
property uses the
CCDFMeasurementsSpecification
properties.
The CCDFMeasurementsSpecification
properties are:
PlotGaussianReference
–– Set this property totrue
to plot a reference CCDF curve. The reference CCDF curve represents the power of a complex white Gaussian noise, calculated as a chi-squared distribution.Default:
false
Enable
–– Set this property totrue
to enable CCDF measurements. Valid values aretrue
orfalse
.Default:
false
All CCDFMeasurementsSpecification
properties are tunable.
Scope Window Use
Open the CCDF Measurements pane () and enable the Plot Gaussian
reference option.
Visualization
Name
— Window name
"Spectrum Analyzer"
(default) | character vector | string scalar
Title of the scope window.
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
PlotType
— Plot type for normal traces
"Line"
(default) | "Stem"
Specify the type of plot to use for displaying normal traces as either
"Line"
or "Stem"
. Normal traces are traces
that display free-running spectral estimates.
Tunable: Yes
Dependencies
To enable this property, set:
ViewType
to"Spectrum"
or"Spectrum and spectrogram"
PlotNormalTrace
totrue
Scope Window Use
Open the Style properties and set Plot type.
Data Types: char
| string
PlotNormalTrace
— Normal trace flag
true
(default) | false
Set this property to false
to remove the display of the normal
traces. These traces display the free-running spectral estimates. Even when the traces
are removed from the display, the Spectrum Analyzer continues its spectral
computations.
Tunable: Yes
Dependency
To enable this property, set ViewType
to
"Spectrum"
or "Spectrum and
spectrogram"
.
Scope Window Use
Open the Spectrum Settings. In the Trace options section, select Normal trace.
Data Types: logical
PlotMaxHoldTrace
— Max-hold trace flag
false
(default) | true
To compute and plot the maximum-hold spectrum of each input channel, set this property
to true
. The maximum-hold spectrum at each frequency bin is computed
by keeping the maximum value of all the power spectrum estimates. When you toggle this
property, the Spectrum Analyzer resets its maximum-hold computations.
Tunable: Yes
Dependency
To enable this property, set ViewType
to
"Spectrum"
or "Spectrum and
spectrogram"
.
Scope Window Use
Open the Spectrum Settings. In the Trace options section, select Max-hold trace.
Data Types: logical
PlotMinHoldTrace
— Min-hold trace flag
false
(default) | true
To compute and plot the minimum-hold spectrum of each input channel, set this property
to true
. The minimum-hold spectrum at each frequency bin is computed
by keeping the minimum value of all the power spectrum estimates. When you toggle this
property, the Spectrum Analyzer resets its minimum-hold computations.
Tunable: Yes
Dependency
To enable this property, set ViewType
to
"Spectrum"
or "Spectrum and
spectrogram"
.
Scope Window Use
Open the Spectrum Settings. In the Trace options section, select Min-hold trace.
Data Types: logical
ReducePlotRate
— Improve performance with reduced plot rate
true
(default) | false
The simulation speed is faster when this property is set to
true
.
true
— the scope logs data for later use and updates the display at fixed intervals of time. Data occurring between these fixed intervals might not be plotted.false
— the scope updates every time it computes the power spectrum. Use thefalse
setting when you do not want to miss any spectral updates at the expense of slower simulation speed.
Data Types: logical
Title
— Display title
''
(default) | character vector | string scalar
Specify the display title as a character vector or string.
Tunable: Yes
Scope Window Use
Open the Configuration Properties. Set Title.
Data Types: char
| string
YLabel
— Y-axis label
''
(default) | character vector | string scalar
Specify the text for the scope to display to the left of the y-axis.
Regardless of this property, Spectrum Analyzer always displays power units as one of
the SpectrumUnits
values.
Tunable: Yes
Dependency
To enable this property, set ViewType
to
"Spectrum"
or "Spectrum and
spectrogram"
.
Scope Window Use
Open the Configuration Properties. Set Y-label.
Data Types: char
| string
ShowLegend
— Show legend
false
(default) | true
To show a legend with the input names, set this property to
true
.
From the legend, you can control which signals are visible. This control is equivalent to changing the visibility in the Style dialog box. 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.
Note
The legend only shows the first 20 signals. Any additional signals cannot be viewed or controlled from the legend.
Tunable: Yes
Scope Window Use
Open the Configuration Properties. On the Display tab, select Show legend.
Data Types: logical
ChannelNames
— Channel names
empty cell (default) | cell array of character vectors
Specify the input channel names as a cell array of character vectors.
The names appear in the legend, Style dialog box,
and Measurements panels. If you do not specify
names, the channels are labeled as Channel 1
,
Channel 2
, etc.
Tunable: Yes
Dependency
To see channel names, set ShowLegend
to
true
.
Scope Window Use
On the legend, double-click the channel name.
Data Types: char
ShowGrid
— Grid visibility
true
(default) | false
Set this property to true
to show gridlines on the plot.
Tunable: Yes
Scope Window Use
Open the Configuration Properties. On the Display tab, set Show grid.
Data Types: logical
YLimits
— Y-axis limits
[-80, 20]
(default) | [ymin ymax]
Specify the y-axis limits as a two-element numeric vector,
[ymin ymax]
.
Example: scope.YLimits = [-10,20]
Tunable: Yes
Dependencies
To enable this property, set the
ViewType
property to"Spectrum"
or"Spectrum and spectrogram"
.The units directly depend upon the
SpectrumUnits
property.
Scope Window Use
Open the Configuration Properties. Set Y-limits (maximum) and Y-limits (minimum).
ColorLimits
— Scale spectrogram color limits
[-80, 20]
(default) | [colorMin colorMax]
Control the color limits of the spectrogram using a two-element numeric vector,
[colorMin colorMax]
.
Example: scope.ColorLimits = [-10,20]
Dependencies
To enable this property, set the
ViewType
property to"Spectrogram"
or"Spectrum and spectrogram"
.The units directly depend upon the
SpectrumUnits
property.
Scope Window Use
Open the Configuration Properties. Set Color-limits (minimum) and Color-limits (maximum).
AxesScaling
— Axes scaling mode
"Auto"
(default) | "Manual"
| "OnceAtStop"
| "Updates"
Specify when the scope automatically scales the axes. Valid values are:
"Auto"
— The scope scales the axes as-needed 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 once after 10 updates.
Scope Window Use
Select Tools > Axes Scaling.
Data Types: char
| string
AxesScalingNumUpdates
— Number of updates before scaling
"10"
(default) | integer character vector | integer string scalar
Set this property to delay auto scaling the y-axis.
Dependency
To enable this property, set AxesScaling
to
"Updates"
.
Scope Window Use
Open the Axes Scaling dialog box and set Number of updates.
Data Types: char
| string
AxesLayout
— Orientation of the spectrum and spectrogram
"Vertical"
(default) | "Horizontal"
Specify the layout type as "Horizontal"
or
"Vertical"
. A vertical layout stacks the spectrum above the
spectrogram. A horizontal layout puts the two views side-by-side.
Tunable: Yes
Dependency
To enable this property, set ViewType
to "Spectrum
and spectrogram"
.
Scope Window Use
Open the Spectrum Settings. Set Axes layout.
Data Types: char
| string
OpenAtSimulationStart
— Open scope when starting simulation
true
(default) | 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 at the start
of simulation.
Scope Window Use
Select File > Open at Start of Simulation.
Data Types: logical
Visible
— Visibility of the Spectrum Analyzer
false
| true
Set this property to true
to show the spectrum
analyzer window, or false
to hide the spectrum
analyzer window.
Examples
Construct a Spectrum Analyzer Configuration Object
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 = SpectrumAnalyzerConfiguration with properties: NumInputPorts: '1' InputDomain: 'Time' SpectrumType: 'Power' ViewType: 'Spectrum' SampleRateSource: 'Inherited' Method: 'Welch' PlotAsTwoSidedSpectrum: 1 FrequencyScale: 'Linear' Advanced FrequencySpan: 'Full' FrequencyResolutionMethod: 'RBW' RBWSource: 'Auto' OverlapPercent: '0' Window: 'Hann' SpectrumUnits: 'dBm' AveragingMethod: 'Running' SpectralAverages: '1' ReferenceLoad: '1' FrequencyOffset: '0' TreatMby1SignalsAsOneChannel: 1 Spectrogram No properties. Measurements MeasurementChannel: '1' SpectralMask: [1x1 dsp.scopes.SpectralMaskSpecification] PeakFinder: [1x1 dsp.scopes.PeakFinderSpecification] CursorMeasurements: [1x1 dsp.scopes.CursorMeasurementsSpecification] ChannelMeasurements: [1x1 dsp.scopes.ChannelMeasurementsSpecification] DistortionMeasurements: [1x1 dsp.scopes.DistortionMeasurementsSpecification] CCDFMeasurements: [1x1 dsp.scopes.CCDFMeasurementsSpecification] Visualization Name: 'SpectrumAnalyzer' Position: [240 287 800 450] PlotType: 'Line' PlotNormalTrace: 1 PlotMaxHoldTrace: 0 PlotMinHoldTrace: 0 ReducePlotRate: 1 Title: '' YLabel: '' ShowLegend: 0 ChannelNames: {''} ShowGrid: 1 YLimits: [-80 20] AxesScaling: 'Auto' OpenAtSimulationStart: 1 Visible: 0
Obtain Measurements Data Programmatically for Spectrum Analyzer Block
Compute and display the power spectrum of a noisy sinusoidal input signal using the Spectrum Analyzer block. Measure the peaks, cursor placements, adjacent channel power ratio, distortion, and CCDF values in the spectrum by enabling these block configuration properties:
PeakFinder
CursorMeasurements
ChannelMeasurements
DistortionMeasurements
CCDFMeasurements
Open and Inspect the Model
Filter a streaming noisy sinusoidal input signal using a Lowpass Filter block. The input signal consists of two sinusoidal tones: 1 kHz and 15 kHz. The noise is white Gaussian noise with zero mean and a variance of 0.05. The sampling frequency is 44.1 kHz. Open the model and inspect the various block settings.
model = 'spectrumanalyzer_measurements.slx';
open_system(model)
Access the configuration properties of the Spectrum Analyzer block using the get_param
function.
sablock = 'spectrumanalyzer_measurements/Spectrum Analyzer'; cfg = get_param(sablock,'ScopeConfiguration');
Enable Measurements Data
To obtain the measurements, set the Enable
property of the measurements to true
.
cfg.CursorMeasurements.Enable = true; cfg.ChannelMeasurements.Enable = true; cfg.PeakFinder.Enable = true; cfg.DistortionMeasurements.Enable = true;
Simulate the Model
Run the model. The Spectrum Analyzer block compares the original spectrum with the filtered spectrum.
sim(model)
The right side of the spectrum analyzer shows the enabled measurement panes.
Using getMeasurementsData
Use the getMeasurementsData
function to obtain these measurements programmatically.
data = getMeasurementsData(cfg)
data = 1x5 table SimulationTime PeakFinder CursorMeasurements ChannelMeasurements DistortionMeasurements ______________ __________ __________________ ___________________ ______________________ {[0.9985]} 1x1 struct 1x1 struct 1x1 struct 1x1 struct
The values shown in measurement panes match the values shown in data
. You can access the individual fields of data
to obtain the various measurements programmatically.
Compare Peak Values
As an example, compare the peak values. Verify that the peak values obtained by data.PeakFinder
match with the values seen in the Spectrum Analyzer
window.
peakvalues = data.PeakFinder.Value frequencieskHz = data.PeakFinder.Frequency/1000
peakvalues = 26.8441 26.3472 -4.4072 frequencieskHz = 15.0015 1.0049 21.7629
Save and Close the Model
save_system(model); close_system(model);
Version History
Introduced in R2013a
See Also
Functions
Objects
Blocks
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