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SpectrumAnalyzerBlockConfiguration

Configure Spectrum Analyzer block

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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

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Frequently Used

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

Click Settings in the Scope tab and specify Num Inputs.

Data Types: char | string

The domain of the input signal you want to visualize, specified as "Time" or "Frequency". If you visualize time-domain signals, the Spectrum Analyzer transforms the signal to the frequency spectrum based on the algorithm specified in the Method property.

Scope Window Use

In the Estimation tab on the Spectrum Analyzer toolstrip, set Input Domain to Time or Frequency.

Data Types: char | string

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

Dependency

To enable this property, set InputDomain to "Time".

Scope Window Use

In the Scope tab on the Spectrum Analyzer toolstrip, select Spectrum. Click Spectrum to select Power, Power Density, or RMS.

To enable these options, set the Input Domain on the Estimation tab to Time.

Data Types: char | string

Viewer type, specified as one of these values:

  • "Spectrum" — Show the power spectrum.

  • "Spectrogram" — Show 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" — Show spectrum and spectrogram.

To learn more about how the Spectrum Analyzer computes the spectrum and spectrogram, see the Algorithms section in the Spectrum Analyzer block reference page.

Tunable: Yes

Scope Window Use

In the Scope tab on the Spectrum Analyzer toolstrip, select Spectrum, Spectrogram, or both.

Data Types: char | string

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 the SampleRate 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

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

Spectrum estimation method, specified as one of the following:

  • "Filter bank" –– Use an analysis filter bank to estimate the power spectrum. Compared to Welch's method, this method has a lower noise floor, better frequency resolution, lower spectral leakage, and requires fewer samples per update.

  • "Welch" –– Use Welch's method of averaged modified periodograms.

For more information on these methods, see Algorithms.

Tunable: Yes

Dependency

To enable this property, set InputDomain to "Time".

Scope Window Use

In the Estimation tab of the Spectrum Analyzer toolstrip, set Estimation Method to Filter bank or Welch.

To enable this parameter, set Input Domain to Time in the Estimation tab.

Data Types: char | string

Option to plot a two-sided spectrum, specified as one of the following:

  • true — Compute and plot two-sided spectral estimates. When the input signal is complex valued, you must set this property to true.

  • false — Compute and plot one-sided spectral estimates. If you set this property to false, 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 to true, except at 0 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, see pwelch.

Tunable: Yes

Scope Window Use

Click the Spectrum tab or the Spectrogram tab (if enabled) 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

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 the PlotAsTwoSidedSpectrum property to true.

  • "Log" — Use a logarithmic scale to display frequencies on the x-axis. To use the "Log" option, you must also set the PlotAsTwoSidedSpectrum property to false.

Tunable: Yes

Scope Window Use

Click the Spectrum tab or the Spectrogram tab (if enabled) 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 or the Spectrogram tab (if enabled). If you select the Two-Sided Spectrum check box, then you must set the Frequency Scale to Linear.

Data Types: char | string

Plot type to display normal traces, specified as "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 to true.

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.

To enable the Plot Type, you must:

  • Select Spectrum in the Views section of the Scope tab.

  • Enable the Normal Trace check box in the Trace Options section of the Spectrum tab.

Data Types: char | string

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 the AxesScalingNumUpdates property.

Tunable: Yes

Data Types: char | string

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

Since R2024a

Frequency resolution method of the spectrum analyzer, specified as one of these options.

  • "RBW" –– The RBWSource and RBW properties control the frequency resolution (in Hz) of the analyzer.

  • "Number of frequency bands" –– Applies only when you set Method to "filter-bank". The FFTLengthSource and FFTLength properties control the frequency resolution.

  • "Window length" –– Applies only when you set Method to "welch". The WindowLength property controls the frequency resolution.

Tunable: Yes

Dependency

To enable this property, set InputDomain to "Time".

Scope Window Use

Click the Estimation tab on the Spectrum Analyzer toolstrip. In the Frequency Resolution section, set Resolution Method to one of the available options.

Data Types: char | string

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 the RBW 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

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:

spanRBW>2

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

Since R2024b

Set this property to true to maintain the number of samples per update Nsamples at 1024 regardless of the window you choose in the Window property. The RBW value adjusts according to the window you choose.

Nsamples=(1−Op100)×NENBW×FsRBW

where,

  • Op is the overlap percent you specify in the OverlapPercent property.

  • Fs is the sample rate you specify using the SampleRateSource and SampleRate properties.

  • RBW is the resolution bandwidth you specify in the RBWSource and RBW properties.

  • NENBW is the normalized effective noise bandwidth. For more information, see the Spectrum Analyzer block reference page.

When you set this parameter to false or 0, the object maintains the same RBW value and adjusts the required number of samples per update Nsamples depending on the window you choose.

Tunable: Yes

Dependencies

To enable this property, set:

  • Method to "Welch".

  • FrequencyResolutionMethod to "RBW".

  • RBWSource to "Auto".

Data Types: logical

Since R2024a

Window length in samples that is used to compute the spectral estimates, specified as an integer greater than 2. This property controls the frequency resolution based on the value of the window length.

Tunable: Yes

Dependencies

To enable this property, set:

  • Method to "Welch".

  • FrequencyResolutionMethod to "Window length".

Scope Window Use

Click the Estimation tab on the Spectrum Analyzer toolstrip. In the Frequency Resolution section, set the Window Length to a positive integer greater than 2.

To enable Window Length, set:

  • Estimation Method to Welch.

  • Resolution Method to Window length.

Since R2024a

Source of the FFT length, specified as one of these:

  • "Auto" –– The value of FFT length depends on the setting of the frequency resolution method. When you set:

    • FrequencyResolutionMethod to "RBW", the FFT length equals the number of samples per update, Nsamples. For more details on Nsamples, see the Algorithms section in the Spectrum Analyzer page.

    • FrequencyResolutionMethod to "Window length", the FFT length equals the value you specify in the WindowLength property or 1024, whichever is larger.

    • FrequencyResolutionMethod to "Number of frequency bands", the FFT length equals the input frame size (number of rows).

  • "Property" –– The number of FFT points equals the value you specify in the FFTLength property.

Tunable: Yes

Dependency

To enable this property, set:

  • Method to "Welch".

  • Method to "Filter bank" and FrequencyResolutionMethod to "Number of frequency bands".

Scope Window Use

Click the Estimation tab on the Spectrum Analyzer toolstrip. In the Frequency Resolution section, set the FFT Length to Auto or a positive integer.

Data Types: char | string

Since R2024a

Length of the FFT that the spectrum analyzer uses to compute spectral estimates, specified as a positive integer.

Tunable: Yes

Dependencies

To enable this property, set FFTLengthSource to "Property".

Scope Window Use

Click the Estimation tab on the spectrum analyzer toolstrip. In the Frequency Resolution section, set the FFT Length to Auto or a positive integer.

Sharpness of the prototype lowpass filter, specified as a character vector or a string scalar of a real nonnegative scalar in the range [0,1].

Increasing the filter sharpness decreases the spectral leakage and gives a more accurate power reading.

Tunable: Yes

Dependencies

To enable this property, set:

  • InputDomain to "Time".

  • Method to "Filter Bank".

Scope Window Use

Click the Estimation tab on the Spectrum Analyzer toolstrip. In the Frequency Resolution section, set Filter Sharpness.

To enable this parameter, set Input Domain to Time and Estimation Method to Filter bank in the Estimation tab.

Data Types: char | string

Frequency span mode, specified as one of the following:

  • "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 the Span and CenterFrequency properties.

  • "Start and stop frequencies" –– The Spectrum Analyzer computes and plots the spectrum over the interval specified by the StartFrequency and StopFrequency properties.

Tunable: Yes

Dependency

To enable this property, set InputDomain to "Time".

Scope Window Use

Click the Estimation tab on the Spectrum Analyzer toolstrip. In the Frequency Options section, set Frequency Span to Full, Span and Center Frequency, or Start and Stop Frequencies.

To enable the Frequency Span, set Input Domain to Time.

Data Types: char | string

Frequency span over which the Spectrum Analyzer computes and plots the spectrum, specified as a character vector or a string scalar of a real positive scalar in Hz. The overall span, defined by this property and the CenterFrequency property, must fall within the Nyquist Frequency Interval.

Tunable: Yes

Dependency

To enable this property, set:

  • InputDomain to "Time".

  • FrequencySpan to "Span and center frequency".

Data Types: char | string

Center of the frequency span over which the Spectrum Analyzer computes and plots the spectrum, specified as a character vector or a string scalar of a real scalar in Hz. The overall frequency span, defined by Span and this property, must fall within the Nyquist Frequency Interval.

Tunable: Yes

Dependency

To enable this property, set:

  • InputDomain to "Time".

  • FrequencySpan to "Span and center frequency".

Scope Window Use

Click the Estimation tab on the Spectrum Analyzer toolstrip. In the Frequency Options section, set Frequency Span to Span and Center Frequency and Center Frequency (Hz) to a real scalar.

To enable the Frequency Span, set Input Domain to Time.

Data Types: char | string

Starting frequency value in the frequency interval over which the Spectrum Analyzer computes and plots the spectrum, specified as a character vector or a string scalar of a real scalar in Hz. The overall span, which is defined by this property and StopFrequency, must fall within the Nyquist Frequency Interval.

Tunable: Yes

Dependency

To enable this property, set:

  • InputDomain to "Time".

  • FrequencySpan to "Start and stop frequencies".

Scope Window Use

Click the Estimation tab on the Spectrum Analyzer toolstrip. In the Frequency Options section, set Frequency Span to Start and Stop Frequencies and Start Frequency (Hz) to a real scalar.

To enable the Frequency Span, set Input Domain to Time.

Data Types: char | string

Ending frequency value in the frequency interval over which the Spectrum Analyzer computes and plots the spectrum, specified as a character vector or a string scalar of a real scalar in Hz. The overall span, which is defined by this property and the StartFrequency property, must fall within the Nyquist Frequency Interval.

Tunable: Yes

Dependency

To enable this property, set:

  • InputDomain to "Time".

  • FrequencySpan to "Start and stop frequencies".

Scope Window Use

Click the Estimation tab on the Spectrum Analyzer toolstrip. In the Frequency Options section, set Frequency Span to Start and Stop Frequencies and Stop Frequency (Hz) to a real scalar.

To enable the Frequency Span, set Input Domain to Time.

Data Types: char | string

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

Dependency

To enable this property, set:

  • InputDomain to "Time".

  • Method to "Welch"

Scope Window Use

Click the Estimation tab on the Spectrum Analyzer toolstrip. In the Window Options section, set the Overlap (%).

To enable the Overlap (%), set Input Domain to Time and Estimation Method to Welch in the Estimation tab on the Spectrum Analyzer toolstrip.

Data Types: char | string

Specify a window function for the spectral estimator. You can select one of the window options in the following table or specify a custom window. For more information on the window functions, click the link to the function reference page in the Signal Processing Toolbox™ documentation.

Window OptionCorresponding 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

Dependency

To enable this property, set:

  • InputDomain to "Time".

  • Method to "Welch"

Scope Window Use

Click the Estimation tab on the Spectrum Analyzer toolstrip. In the Window Options section, set the Window.

To enable the Window, set Input Domain to Time and Estimation Method to Welch in the Estimation tab on the Spectrum Analyzer toolstrip.

Data Types: char | string

Name of the custom window function, specified as a character vector or string scalar. The name of the custom window function must be on the MATLAB® path. Use this property 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

Click the Estimation tab on the Spectrum Analyzer toolstrip. In the Window Options section, for the Window, enter the name of the custom window function.

Data Types: char | string

Sidelobe attenuation of the window in decibels (dB), specified as a character vector or a string scalar of a positive scalar greater than or equal to 45.

Tunable: Yes

Dependency

To enable this property, set Window to "Chebyshev" or "Kaiser".

Scope Window Use

Click the Estimation tab on the Spectrum Analyzer toolstrip. In the Window Options section, set the Attenuation (dB).

To enable the Attenuation (dB), set:

  • Input Domain to Time

  • Estimation Method to Welch

  • Window to either Chebyshev or Kaiser in the Estimation tab on the Spectrum Analyzer toolstrip.

Data Types: char | string

Averaging method, specified as one of the following:

  • "VBW" — Video bandwidth method. The object uses a lowpass filter to smooth the trace and decrease noise. Use the VBWSource and VBW properties to specify the VBW value.

  • "Exponential" — Weighted average of samples. The object computes the average over samples weighted by an exponentially decaying forgetting factor. Use the ForgettingFactor property to specify the weighted forgetting factor.

For more information, see Averaging Method.

Tunable: Yes

Dependency

To enable this property, set InputDomain to "Time".

Scope Window Use

Click the Estimation tab on the Spectrum Analyzer toolstrip. In the Averaging section, set Averaging Method to VBW or Exponential.

To enable the Averaging Method, set Input Domain to Time.

Data Types: char | string

Source of the video bandwidth (VBW), specified as one of these options:

  • "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 the VBW property.

For more details on the video bandwidth method, see Averaging Method.

Tunable: Yes

Dependency

To enable this property, set InputDomain to "Time" and 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 Input Domain to Time and Averaging Method to VBW.

Data Types: char | string

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 either Auto or enter a positive real scalar that is less than or equal to Sample Rate (Hz)/2.

To enable the VBW (Hz), set Input Domain to Time and Averaging Method to VBW.

Data Types: double

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:

  • InputDomain to "Time"

  • AveragingMethod to "Exponential"

Scope Window Use

Click the Estimation tab on the Spectrum Analyzer toolstrip. In the Averaging section, set Forgetting Factor.

To enable the Forgetting Factor, set Input Domain to Time and Averaging Method to Exponential.

Data Types: char | string

Source of the frequency vector, specified as one of the following:

  • "Auto" — The Spectrum Analyzer computes the frequency vector based on the frame size of the input signal and the specified sample rate. For more details, see Frequency Vector.

  • "Property" — Enter a custom vector in the FrequencyVector property.

  • "InputPort" — An input port appears on the Spectrum Analyzer block. Specify the frequency vector input through this port.

Tunable: Yes

Dependency

To enable this property, set InputDomain to "Frequency".

Scope Window Use

Click the Estimation tab on the Spectrum Analyzer toolstrip. In the Domain section, set Frequency (Hz) to Auto, Input port, or a monotonically increasing vector of length equal to the input signal frame size.

To enable the Frequency (Hz), set Input Domain to Frequency.

Data Types: char | string

Custom frequency vector, specified as a monotonically increasing vector. This vector determines the x-axis in the display. The vector must be monotonically increasing and must have the same length as the input signal frame size.

Tunable: Yes

Dependency

To enable this property, set:

  • InputDomain to "Frequency".

  • FrequencyVectorSource to "Property".

Scope Window Use

Click the Estimation tab on the Spectrum Analyzer toolstrip. In the Domain section, set Frequency (Hz) to a monotonically increasing vector of length equal to the input signal frame size.

To enable the Frequency (Hz), set Input Domain to Frequency.

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64

Units of the frequency-domain input, specified as "dBm", "dBuV", "dBV", "dBW", "Vrms", "Watts", or "none". This property allows the Spectrum Analyzer to scale frequency data if you choose a different display unit in the SpectrumUnits property.

Tunable: Yes

Dependency

To enable this property, set InputDomain to "Frequency".

Scope Window Use

Click the Estimation tab on the Spectrum Analyzer toolstrip. In the Domain section, set Input Unit.

To enable the Input Unit, set Input Domain to Frequency.

Data Types: char | string

Units of the spectrum, specified as one of these:

  • "dBm"

  • "dBuV" (since R2023b)

  • "dBFS"

  • "dBV"

  • "dBW"

  • "Vrms"

  • "Watts"

  • "dBm/Hz"

  • "dBW/Hz"

  • "dBFS/Hz"

  • "Watts/Hz"

  • "Auto"

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.

InputDomainSpectrumTypeAllowed SpectrumUnits
"Time""Power""dBm", "dBW", "dBFS", "Watts"
"Power density""dBm/Hz", "dBW/Hz","dBFS/Hz", "Watts/Hz"
"RMS""dBV", "dBuV" (since R2023b), "Vrms"
"Frequency"―"Auto", "dBm", "dBuV" (since R2023b), "dBV", "dBW", "Vrms", "Watts"

If you set the InputDomain property to "Frequency" and the SpectrumUnits property to "Auto", the Spectrum Analyzer assumes the spectrum units to be equal to input units specified in the InputUnits property. If you set InputDomain to "Time" and SpectrumUnits to any option other than "Auto", then the Spectrum Analyzer converts the units specified in InputUnits to the units specified in SpectrumUnits.

Scope Window Use

Click the Spectrum tab on the Spectrum Analyzer toolstrip. In the Scale section, set Spectrum Unit.

Data Types: char | string

Source of dBFS scaling factor, specified as one of these:

  • "Auto" –– The Spectrum Analyzer adjusts the scaling factor based on the input data.

  • "Property" –– Specify the full-scale scaling factor using the FullScale property.

Tunable: Yes

Dependency

To enable this property, set:

  • InputDomain to "Time"

  • SpectrumType to "Power" or "Power density"

  • SpectrumUnits to "dBFS" or "dBFS/Hz" (when spectrum type is set to "Power density")

Scope Window Use

Click the Spectrum tab on the Spectrum Analyzer toolstrip. In the Scale section, set the Full Scale to either Auto or a positive scalar.

To enable the Full Scale:

  • In the Scope tab, set the spectrum type to Power or Power Density.

  • In the Estimation tab, set Input Domain to Time.

  • In the Spectrum tab, set Spectrum Unit to dBFS or dBFS/Hz (when spectrum type is set to Power Density).

Data Types: char | string

dBFS full scale value, specified as a character vector or a string scalar of a real positive scalar.

Tunable: Yes

Dependency

To enable this property, set:

  • InputDomain to "Time"

  • SpectrumType to "Power" or "Power density"

  • SpectrumUnits to "dBFS" or "dBFS/Hz" (when spectrum type is set to "Power density")

  • FullScaleSource to "Property"

Scope Window Use

Click the Spectrum tab on the Spectrum Analyzer toolstrip. In the Scale section, set the Full Scale to either Auto or enter a positive scalar.

To enable the Full Scale:

  • In the Scope tab, set the spectrum type to Power or Power Density.

  • In the Estimation tab, set Input Domain to Time.

  • In the Spectrum tab, set Spectrum Unit to dBFS or dBFS/Hz (when spectrum type is set to Power Density).

Data Types: char | string

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

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 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.

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

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

Spectrogram

Channel for which the Spectrum Analyzer plots the spectrogram, specified as a character vector or string scalar of a positive scalar integer in the range [1 N], where N is the number of input channels.

Tunable: Yes

Dependency

To enable this property, set ViewType to "Spectrogram" or "Spectrum and spectrogram".

Scope Window Use

Click the Spectrogram tab on the Spectrum Analyzer toolstrip. In the Channel section, select a Channel.

Data Types: char | string

Source of the time resolution value of each spectrogram line, , specified as "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:

  • InputDomain to "Time".

  • ViewType to "Spectrogram" or "Spectrum and spectrogram".

Scope Window Use

Click the Spectrogram tab on the Spectrum Analyzer toolstrip. In the Time Options section, set the Time Resolution (s) to Auto or enter a positive scalar.

To enable the Time Resolution (s), select Spectrogram in the Scope tab and set Input Domain to Time in the Estimation tab.

Data Types: char | string

Time resolution of each spectrogram line, specified as a character vector or a string scalar of a positive scalar and expressed in seconds.

The Spectrum Analyzer determines the time resolution value based on the frequency resolution method, RBW, and time resolution properties.

MethodRBWTime ResolutionResulting Time Resolution in Seconds
Welch or Filter BankAutoAuto1/RBW
Welch or Filter BankAutoManually entered1/Time Resolution Hz
Welch or Filter BankManually enteredAuto1/RBW seconds
Welch or Filter BankManually enteredManually enteredEqual to or greater than the minimum attainable time resolution 1/RBW. The Spectrum Analyzer combines several spectral estimates into one spectrogram line to obtain the desired time resolution. It uses interpolation to obtain time resolution values that are not integer multiples of 1/RBW.

Tunable: Yes

Dependency

To enable this property, set:

  • InputDomain to "Time".

  • ViewType to "Spectrogram" or "Spectrum and spectrogram".

  • TimeResolutionSource to "Property.

Scope Window Use

Click the Spectrogram tab on the Spectrum Analyzer toolstrip. In the Time Options section, set the Time Resolution (s) to Auto or enter a positive scalar.

To enable the Time Resolution (s), select Spectrogram in the Scope tab and set Input Domain to Time in the Estimation tab.

Data Types: char | string

Source of the time span of the spectrogram, specified as "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

Click the Spectrogram tab on the Spectrum Analyzer toolstrip. In the Time Options section, set the Time Span (s) to Auto or enter a positive scalar.

Data Types: char | string

Time span of the spectrogram display in seconds, specified as a character vector or string scalar of a positive scalar. 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.

Tunable: Yes

Dependency

To enable this property, set:

  • ViewType to "Spectrogram" or "Spectrum and spectrogram".

  • TimeSpanSource to "Property".

Scope Window Use

Click the Spectrogram tab on the Spectrum Analyzer toolstrip. In the Time Options section, set the Time Span (s) to Auto or enter a positive scalar.

Data Types: char | string

Measurements

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

Channel measurements, specified as a ChannelMeasurementsConfiguration object. Enable channel measurements to compute and display the occupied bandwidth or adjacent channel power ratio. All ChannelMeasurementsConfiguration properties are tunable.

Tunable: Yes

Dependency

To enable this property, set ViewType to "Spectrum" or "Spectrum and spectrogram".

Scope Window Use

Click the Channel Measurements tab on the Spectrum Analyzer toolstrip and modify the measurement settings.

The Channel Measurements tab appears when you select Spectrum in the Scope tab.

Cursor measurements, specified as a CursorMeasurementsConfiguration object. Enable cursor measurements to display waveform cursors. All CursorMeasurementsConfiguration properties are tunable.

Tunable: Yes

Dependency

To enable this property, set ViewType to "Spectrum" or "Spectrum and spectrogram".

Scope Window Use

Click the Measurements tab on the Spectrum Analyzer toolstrip and modify the cursor measurements in the Cursors section.

The Measurements tab appears when you select Spectrum in the Scope tab.

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

Dependency

To enable this property, set ViewType to "Spectrum" or "Spectrum and spectrogram".

Scope Window Use

Click the Measurements tab on the Spectrum Analyzer toolstrip and modify the distortion measurements in the Distortion section.

The Measurements tab appears when you select Spectrum in the Scope tab.

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

Dependency

To enable this property, set ViewType to "Spectrum" or "Spectrum and spectrogram".

Scope Window Use

Click the Measurements tab on the Spectrum Analyzer toolstrip and modify the peak finder measurements in the Peaks section.

The Measurements tab appears when you select Spectrum in the Scope tab.

Spectral mask configuration, specified as a SpectralMaskConfiguration object. Use the spectral mask configuration to draw upper, lower, or upper and lower mask lines in the power and power-density plots. All SpectralMaskConfiguration properties are tunable.

Tunable: Yes

Dependency

To enable this property, set:

  • ViewType to "Spectrum" or "Spectrum and spectrogram".

  • SpectrumType to either "Power" or "Power density".

Scope Window Use

Click the Spectral Mask tab on the Spectrum Analyzer toolstrip and modify the settings.

The Spectral Mask tab appears when you:

  • Select Spectrum in the Scope tab.

  • In the drop-down list under Spectrum, choose either Power or Power Density.

Visualization

Caption to display in the scope window, specified as a character vector or string scalar.

Tunable: Yes

Data Types: char | string

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

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 Maximize button control on the Spectrum Analyzer display to maximize the axes.

Data Types: char | string

Normal trace flag, specified as true or false.

To remove normal traces from the display, set this property to false. These traces display the free-running spectral estimates. The Spectrum Analyzer continues its spectral computations even when you set this property to false.

Tunable: Yes

Dependency

To enable this property, set ViewType to "Spectrum" or "Spectrum and spectrogram".

Scope Window Use

Click the Spectrum tab on the Spectrum Analyzer toolstrip and select the Normal Trace check box in the Trace Options section.

To enable the Normal Trace check box, select Spectrum in the Scope tab.

Data Types: logical

Maximum-hold trace flag, specified as false or true.

To compute and plot the maximum-hold spectrum of each input channel, set this property to true. The Spectrum Analyzer computes the maximum-hold spectrum at each frequency bin 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

Click the Spectrum tab on the Spectrum Analyzer toolstrip and select the Max-Hold Trace check box in the Trace Options section.

To enable the Max-Hold Trace check box, select Spectrum in the Scope tab.

Data Types: logical

Minimum-hold trace flag, specified as false or true.

To compute and plot the minimum-hold spectrum of each input channel, set this property to true. The Spectrum Analyzer computes the minimum-hold spectrum at each frequency bin 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

Click the Spectrum tab on the Spectrum Analyzer toolstrip and select the Min-Hold Trace check box in the Trace Options section.

To enable the Min-Hold Trace check box, select Spectrum in the Scope tab.

Data Types: logical

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, and enter Title.

Data Types: char | string

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

Dependency

To enable this property, set ViewType to "Spectrum" or "Spectrum and spectrogram".

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.

To enable the Y-Label, select Spectrum in the Scope tab.

Data Types: char | string

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

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

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-Limits.

To enable the Y-Limits, select Spectrum in the Scope tab.

Color limits of the spectrogram, specified as a two-element numeric vector of the form [colorMin colorMax]. The units of the color limits directly depend upon the SpectrumUnits property.

Example: scope.ColorLimits = [-10,20]

Tunable: Yes

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

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 Color Limits.

To enable the Color Limits, select Spectrogram in the Scope tab.

Color lookup table, specified as a valid colormap name or a three-column matrix with values in the range [0,1] defining RGB triplets.

Tunable: Yes

Dependencies

To enable this property, set the ViewType property to "Spectrogram" or "Spectrum and spectrogram".

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 Color Map.

To enable the Color Map, select Spectrogram in the Scope tab.

Data Types: double | char | string

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, and select Show Grid.

Data Types: logical

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

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

Dependencies

To enable this property, set the ViewType property to "Spectrum" or "Spectrum and spectrogram".

Scope Window Use

Click the Scope tab on the Spectrum Analyzer toolstrip. To see the legend, click Legend in the Configuration section.

To enable the Legend, select Spectrum in the Scope tab.

Data Types: logical

Flag to show the color bar, specified as true or false.

Tunable: Yes

Dependencies

To enable this property, set the ViewType property to "Spectrogram" or "Spectrum and spectrogram".

Scope Window Use

Click the Scope tab on the Spectrum Analyzer toolstrip. To see the color bar, click Colorbar in the Configuration section.

To enable the Colorbar, select Spectrogram in the Scope tab.

Data Types: logical

Layout of the axes, specified as one of "Vertical" or "Horizontal". A vertical layout stacks the spectrum above the spectrogram. A horizontal layout places the spectrum next to the spectrogram.

Tunable: Yes

Dependency

To enable this property, set ViewType to "Spectrum and spectrogram".

Scope Window Use

Click the Scope tab on the Spectrum Analyzer toolstrip. Select Spectrum and Spectrogram. In the Configuration section, select and update Layout.

Data Types: char | string

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

Click Settings in the Scope tab. In the Spectrum Analyzer Settings window that opens, select Open at Simulation Start.

Data Types: logical

Set this property to true to display the spectrum analyzer window, and to false to hide the spectrum analyzer window.

Data Types: logical

Examples

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This example uses:

Open Live Script

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'
                     InputDomain: 'Time'
                    SpectrumType: 'Power'
                        ViewType: 'Spectrum'
                SampleRateSource: 'Inherited'
                          Method: 'Filter bank'
          PlotAsTwoSidedSpectrum: 1
                  FrequencyScale: 'Linear'
                        PlotType: 'Line'
                     AxesScaling: 'Auto'

   Advanced
       FrequencyResolutionMethod: 'RBW'
                       RBWSource: 'Auto'
                 FilterSharpness: '0.3'
                   FrequencySpan: 'Full'
                 AveragingMethod: 'VBW'
                       VBWSource: 'Auto'
                   SpectrumUnits: 'dBm'
                   ReferenceLoad: '1'
                 FrequencyOffset: '0'
    TreatMby1SignalsAsOneChannel: 1

   Spectrogram
    No properties.

   Measurements
              MeasurementChannel: '1'
             ChannelMeasurements: [1x1 ChannelMeasurementsConfiguration]
              CursorMeasurements: [1x1 CursorMeasurementsConfiguration]
          DistortionMeasurements: [1x1 DistortionMeasurementsConfiguration]
                      PeakFinder: [1x1 PeakFinderConfiguration]
                    SpectralMask: [1x1 SpectralMaskConfiguration]

   Visualization
                            Name: 'SpectrumAnalyzer'
                        Position: [240 262 800 500]
                    MaximizeAxes: 'Auto'
                 PlotNormalTrace: 1
                PlotMaxHoldTrace: 0
                PlotMinHoldTrace: 0
                           Title: ''
                          YLabel: ''
                         YLimits: [-80 20]
                        ShowGrid: 1
                    ChannelNames: {''}
                      ShowLegend: 0
           OpenAtSimulationStart: 1
                         Visible: 0

This example uses:

Open Model

Compute and display the power spectrum of a noisy sinusoidal input signal using the Spectrum Analyzer block. Measure the cursor placements, adjacent channel power ratio, distortion, and peak values in the spectrum by enabling these block configuration properties:

  • CursorMeasurements

  • ChannelMeasurements

  • DistortionMeasurements

  • PeakFinder

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 a mean of 0 and a variance of 0.05. The sampling frequency is 44.1 kHz. Open the model and inspect the parameter values in the blocks.

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 Enabled property to true.

cfg.CursorMeasurements.Enabled = true;
cfg.ChannelMeasurements.Enabled = true;
cfg.DistortionMeasurements.Enabled = true;
cfg.PeakFinder.Enabled = true;

Simulate the Model

Run the model. The Spectrum Analyzer block compares the original spectrum with the filtered spectrum.

sim(model)

The panes at the bottom of the spectrum analyzer window display the measurements that you have enabled.

Use getMeasurementsData function

Use the getMeasurementsData function to obtain the measurements programmatically.

data = getMeasurementsData(cfg)

data =

  1x5 table

    SimulationTime    PeakFinder    CursorMeasurements    ChannelMeasurements    DistortionMeasurements
    ______________    __________    __________________    ___________________    ______________________

        9.9962        1x1 struct        1x1 struct            1x1 struct               1x1 struct

The values shown in the measurement panels 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 in the spectrum analyzer window.

peakvalues = data.PeakFinder.Value
frequencieskHz = data.PeakFinder.Frequency/1000

peakvalues =

   26.8237
   26.3370
   -5.3604


frequencieskHz =

   15.0015
    1.0049
   12.2739

This example uses:

Open Script

Create a new model based on the dsp_basic_filter template. Add a spectral mask to the Spectrum Analyzer block in the model. Run the model.

Masks are overlaid on the spectrum. If the mask is green, the signal is passing. If the mask is red, the signal is failing. The Spectral Mask panel shows what percentage of the time the mask is succeeding, which mask is failing, how many times the mask(s) failed, and which channels are causing the failure.

  [~,mdl] = fileparts(tempname);
  open_system(new_system(mdl,'FromTemplate','dsp_basic_filter'));
  saBlock = find_system(mdl,'BlockType','SpectrumAnalyzer');

  scopeConfig = get_param(saBlock{1},'ScopeConfiguration');
  upperMask = [0 50; 1200 50; 1200 -10; 24000 -10];
  scopeConfig.SpectralMask.UpperMask = upperMask;
  scopeConfig.SpectralMask.LowerMask = -100;
  scopeConfig.SpectralMask.EnabledMasks = 'upper-and-lower';
  sim(mdl,StopTime='20');

Version History

Introduced in R2013a

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See Also

Functions

Objects

Blocks

Topics