PeakFinderConfiguration

Compute and display the largest calculated peak values on the scope display

Since R2023a

Description

Use the PeakFinderConfiguration object to compute and display peaks in the scope. The scope computes and displays peaks for only the portion of the input signal that is currently on display in the scope.

You can specify the number of peaks you want the scope to display, the minimum height above which you want the scope to detect peaks, the minimum distance between peaks, and label the peaks. You can control the peak finder settings from the scope toolstrip or from the command line. The algorithm defines a peak as a local maximum with lower values present on either side of the peak. It does not consider end points as peaks. For more information on the algorithm, see the findpeaks (Signal Processing Toolbox) function.

To modify the peak finder settings in the scope interface, click the Measurements tab and enable Peak Finder in the Peaks section. Once you enable the Peak Finder, an arrow appears on the plot at each maxima and a Peaks panel appears at the bottom of the scope window.

The SpectrumAnalyzerBlockConfiguration object supports the PeakFinderConfiguration object in the command line.

Spectrum Analyzer Toolstrip

Creation

Syntax

pkfinder = PeakFinderConfiguration()

Description

pkfinder = PeakFinderConfiguration() creates a peak finder configuration object.

Properties

All properties are tunable.

MinHeight — Level above which scope detects peaks

-Inf (default) | real scalar value

Level above which the scope detects peaks, specified as a real scalar.

Scope Window Use

On the Measurements tab, select Peak Finder. In the peak finder settings, specify a real scalar in the Min Height box.

Data Types: double

NumPeaks — Maximum number of peaks to show

3 (default) | positive integer less than 100

Maximum number of peaks to show, specified as a positive integer less than 100.

Scope Window Use

On the Measurements tab, select Peak Finder. In the peak finder settings, specify a positive integer less than 100 in the Num Peaks box.

Data Types: double

MinDistance — Minimum number of samples between adjacent peaks

1 (default) | positive integer

Minimum number of samples between adjacent peaks, specified as a positive integer.

Scope Window Use

On the Measurements tab, select Peak Finder. In the peak finder settings, specify a positive integer in the Min Distance box.

Data Types: double

Threshold — Minimum difference in height of peak and its neighboring samples

0 (default) | nonnegative scalar

Minimum difference in the height of the peak and its neighboring samples, specified as a nonnegative scalar.

Scope Window Use

On the Measurements tab, select Peak Finder. In the peak finder settings, specify a nonnegative scalar in the Threshold box.

Data Types: double

LabelPeaks — Label found peaks

false (default) | true

Label found peaks, specified as true or false. The scope displays the labels (P1, P2, …) above the arrows in the plot.

Scope Window Use

On the Measurements tab, select Peak Finder. In the peak finder settings, select Label Peaks.

Data Types: logical

LabelFormat — Coordinates to display

"x + y" (default) | "x" | "y"

Coordinates to display next to the calculated peak value, specified as "x", "y", or "x + y".

Data Types: char | string

Enabled — Enable peak finder measurements

false (default) | true

Enable peak finder measurements, specified as true or false. Set this property to true to enable the peak finder measurements.

Scope Window Use

On the Measurements tab, select Peak Finder.

Data Types: logical

Examples

Obtain Measurements Data Programmatically for Spectrum Analyzer Block

Open and run the signal amplifier model.

open_system('amplifySigNoise.slx')
sim('amplifySigNoise.slx')

The Spectrum Analyzer blocks in the model show the amplified noise and the signal power plots, respectively. For more details on this model, see the Analysis of Frequency Response of RF System example.

You can obtain or modify the peak, cursor, and distortion measurements in the spectra programmatically by enabling these properties in the SpectrumAnalyzerConfiguration object:

• PeakFinder

• CursorMeasurements

• DistortionMeasurements

Access the configuration properties of the Spectrum Analyzer block using the get_param function.

sablockNoise = 'amplifySigNoise/Noise';
cfgNoise = get_param(sablockNoise,'ScopeConfiguration');
sablockPwr = 'amplifySigNoise/Power';
cfgPwr = get_param(sablockPwr,'ScopeConfiguration');

To enable these measurements, set the Enabled property to true.

cfgNoise.CursorMeasurements.Enabled = true;
cfgNoise.PeakFinder.Enabled = true;
cfgNoise.DistortionMeasurements.Enabled = true;
cfgPwr.CursorMeasurements.Enabled = true;
cfgPwr.PeakFinder.Enabled = true;
cfgPwr.DistortionMeasurements.Enabled = true;

You can now modify these measurements programmatically. As an example, display the first two peaks on the spectrum display. By default, the spectrum shows three peaks. To modify the number of peaks it shows, change NumPeaks to 2. You can even label the peaks using the LabelPeaks property and control the minimum distance between adjacent peaks using the MinDistance property. The changes you make to these properties update the spectra accordingly.

cfgNoise.PeakFinder.NumPeaks = 2;
cfgPwr.PeakFinder.NumPeaks = 2;

Version History

Introduced in R2023a