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CursorMeasurementsConfiguration

Display screen or waveform cursors

    Description

    Use the CursorMeasurementsConfiguration object to enable screen or waveform cursors. You can control the cursor settings from the toolstrip of the scope or from the command line.

    To modify the cursor settings in the scope UI, click the Measurements tab and enable Data Cursors. Each cursor tracks a vertical line along the signal. The scope displays the difference between x- and y-values of the signal at the two cursors in the box between the cursors.

    Spectrum Analyzer Toolstrip

    Snapshot showing cursor measurements in Spectrum Analyzer toolstrip.

    Time Scope Toolstrip

    Snapshot showing cursor measurements in Time Scope toolstrip.

    Array Plot Toolstrip

    Snapshot showing cursor measurements in Array Plot toolstrip.

    Creation

    Description

    example

    cursormeas = CursorMeasurementsConfiguration() creates a cursor measurements configuration object.

    Properties

    expand all

    All properties are tunable.

    x-coordinates of the cursors, specified as a two-element vector of real elements.

    Data Types: double

    Snap cursors to data, specified as true or false.

    Scope Window Use

    Click the Measurements tab on the scope toolstrip. In the Cursors section, click Data Cursors, and then select the Snap to data parameter.

    Data Types: logical

    Enable cursor measurements, specified as true or false. Set this property to true to enable cursor measurements.

    Scope Window Use

    Click the Measurements tab on the scope toolstrip. In the Cursors section, select Data Cursors.

    Data Types: logical

    Examples

    collapse all

    Create a sine wave and view it in the Time Scope. Enable data cursors programmatically.

    Initialization

    Create the input sine wave using the sin function. Create a timescope MATLAB® object to display the signal. Set the TimeSpan property to 1 second.

    f = 100;
    fs = 1000;
    swv = sin(2.*pi.*f.*(0:1/fs:1-1/fs)).';
    scope = timescope(SampleRate=fs,...
        TimeSpanSource="property",...
        TimeSpan=1);

    Data Cursors

    Enable data cursors in the scope programmatically by setting the Enabled property of the CursorMeasurementsConfiguration object to true.

    scope.CursorMeasurements.Enabled = true;
    scope(swv);
    release(scope)

    Compute and display the power spectrum of a noisy sinusoidal input signal using the spectrumAnalyzer MATLAB® object. Measure the peaks, cursor placements, adjacent channel power ratio, and distortion values in the spectrum by enabling these properties:

    • PeakFinder

    • CursorMeasurements

    • ChannelMeasurements

    • DistortionMeasurements

    Initialization

    The input sine wave has two frequencies: 1000 Hz and 5000 Hz. Create two dsp.SineWave System objects to generate these two frequencies. Create a spectrumAnalyzer object to compute and display the power spectrum.

    Fs = 44100;
    Sineobject1 = dsp.SineWave(SamplesPerFrame=1024,PhaseOffset=10,...
        SampleRate=Fs,Frequency=1000);
    Sineobject2 = dsp.SineWave(SamplesPerFrame=1024,...
        SampleRate=Fs,Frequency=5000);
    SA = spectrumAnalyzer(SampleRate=Fs,SpectrumType="power",...
        PlotAsTwoSidedSpectrum=false,ChannelNames={'Power spectrum of the input'},...
        YLimits=[-120 40],ShowLegend=true);
        

    Enable Measurements Data

    To obtain the measurements, set the Enabled property to true.

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

    Use getMeasurementsData

    Stream in the noisy sine wave input signal and estimate the power spectrum of the signal using the spectrum analyzer. Measure the characteristics of the spectrum. Use the getMeasurementsData function to obtain these measurements programmatically. The isNewDataReady function returns true when there is new spectrum data. Store the measured data in the variable data.

    data = [];
    for Iter = 1:1000
        Sinewave1 = Sineobject1();
        Sinewave2 = Sineobject2();
        Input = Sinewave1 + Sinewave2;
        NoisyInput = Input + 0.001*randn(1024,1);
        SA(NoisyInput);
         if SA.isNewDataReady
            data = [data;getMeasurementsData(SA)];
         end
    end

    The right side of the spectrum analyzer shows the measurement panes you enabled. The values in these panes match the values in the last time step of the data variable. You can access the individual fields of data to obtain the various measurements programmatically.

    Compare Peak Values

    Use the PeakFinder property to obtain peak values. Verify that the peak values in the last time step of data match the values shown on the spectrum analyzer plot.

    peakvalues = data.PeakFinder(end).Value 
    peakvalues = 3×1
    
       26.9261
       24.1149
      -46.3163
    
    
    frequencieskHz = data.PeakFinder(end).Frequency/1000
    frequencieskHz = 3×1
    
        4.9957
        0.9905
        0.0646
    
    

    Version History

    Introduced in R2022a