CursorMeasurementsConfiguration

Display waveform cursors

Description

Use the CursorMeasurementsConfiguration object to enable 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

Time Scope Toolstrip

Array Plot Toolstrip

Dynamic Filter Visualizer Toolstrip

Creation

Syntax

cursormeas = CursorMeasurementsConfiguration()

Description

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

Properties

All properties are tunable.

XLocation — x-coordinates of the cursors

[2 8] (default) | two-element vector

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

Scope Window Use

Click the Measurements tab on the scope toolstrip. In the Cursors section, select Data Cursors and click the drop-down for Data Cursors. Specify the two elements in X location edit fields.

Data Types: double

SnapToData — Snap cursors to data

false (default) | true

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 the drop-down for Data Cursors, and then select Snap to data.

Data Types: logical

LockSpacing — Lock spacing between cursors

false (default) | true

Set this property to true to lock the spacing between the cursors.

Scope Window Use

Click the Measurements tab on the scope toolstrip. In the Cursors section, click the drop-down for Data Cursors, and then select Lock cursor spacing.

Data Types: logical

Enabled — Enable cursor measurements

false (default) | true

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

Configure Cursor Measurements Programmatically in Time Scope MATLAB Object

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)

Obtain Measurements Data Programmatically for spectrumAnalyzer object

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 bottom 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

  -59.4124
  -59.8725
  -60.0010

frequencieskHz = data.PeakFinder(end).Frequency/1000

frequencieskHz = 3×1

    0.2799
    0.5383
    0.6029

Version History

Introduced in R2022a

R2022b: Enhancements to Data Cursor Measurements

Starting in R2022b, the CursorMeasurementsConfiguration object has the new LockSpacing property. Using this property, you can lock the spacing between waveform cursors in the scope window.

In the Measurements tab of the scope UI window, these data cursor settings are new:

• Lock cursor spacing –– This setting corresponds to the LockSpacing property in the CursorMesaurementsConfiguration object.

• X location –– These fields are enabled and correspond to the XLocation property in the CursorMesaurementsConfiguration object.

R2022b: Support for waveform cursors in spectrogram mode

Starting in R2022b, the Spectrum Analyzer supports data cursors even when the scope shows only the spectrogram display.

In the command line, you can edit the CursorMeasurementsConfiguration object when you set the ViewType property of the spectrumAnalyzer object to "spectrogram".