isNewDataReady

Check spectrum analyzer for new data

Syntax

flag = isNewDataReady(scope)

Description

flag = isNewDataReady(scope) indicates whether the spectrum analyzer scope displays new spectral estimates. When logging spectrum analyzer data from the spectrumAnalyzer scope, use this function to ignore duplicate spectra from the getSpectrumData function.

Examples

Log Spectrum Data

Generate a discrete sine wave. Then display the sine wave signal using the Spectrum Analyzer. While the Spectrum Analyzer is running, save the spectrum data to a table. The Spectrum Analyzer does not update at every time step. To avoid saving that redundant spectrum data, use the isNewDataReady function.

wave = dsp.SineWave(Frequency=100,SampleRate=1000);
wave.SamplesPerFrame = 1000;
scope = spectrumAnalyzer(SampleRate=wave.SampleRate,...
    ViewType="spectrum-and-spectrogram");
data = [];

for ii = 1:250
    x = wave() + 0.05*randn(1000,1);
    scope(x);
    if scope.isNewDataReady
        data = [data;getSpectrumData(scope)];
    end
end

release(scope);

Show the first five rows in the table. You can see gaps in the simulation time in the data table. The missing rows indicate times where the Spectrum Analyzer was waiting for additional samples to update the spectrum. The isNewDataReady function prevented the script from saving that redundant data.

data(1:5,:)

ans =

  5×4 table

    SimulationTime       Spectrum           Spectrogram       FrequencyVector
    ______________    _______________    _________________    _______________

      {[0.9990]}      {1024×1 double}    {100×1024 double}    {1024×1 double}
      {[1.9990]}      {1024×1 double}    {100×1024 double}    {1024×1 double}
      {[2.9990]}      {1024×1 double}    {100×1024 double}    {1024×1 double}
      {[4.9990]}      {1024×1 double}    {100×1024 double}    {1024×1 double}
      {[9.9990]}      {1024×1 double}    {100×1024 double}    {1024×1 double}

Input Arguments

scope — Spectrum analyzer

object name

Spectrum analyzer from which you want to save data, specified as a spectrumAnalyzer object.

Output Arguments

flag — Flag indicating new data

true | false

Flag indicating new data, returned as one of these:

• true –– The Spectrum Analyzer shows new data.

• false –– The Spectrum Analyzer shows the same spectrum and no new data is available.

Version History

Introduced in R2017b

R2024a: dsp.SpectrumAnalyzer System object warns

The dsp.SpectrumAnalyzer System object™ warns in R2024a. Use the spectrumAnalyzer object instead.

Update Code

No updates to your code are required except replacing instances of dsp.SpectrumAnalyzer with spectrumAnalyzer.

This table shows how the isNewDataReady function typically uses the dsp.SpectrumAnalyzer System object and explains how to update existing code to use the spectrumAnalyzer object.

Discouraged Usage	Recommended Replacement
wave = dsp.SineWave('Frequency',100,'SampleRate',1000); wave.SamplesPerFrame = 1000; scope = dsp.SpectrumAnalyzer('SampleRate',wave.SampleRate,... 'ReducePlotRate',false,... 'ViewType','Spectrum and spectrogram'); data = []; for ii = 1:250 x = wave() + 0.05*randn(1000,1); scope(x); if scope.isNewDataReady data = [data;getSpectrumData(scope)]; end end release(scope);	wave = dsp.SineWave(Frequency=100,SampleRate=1000); wave.SamplesPerFrame = 1000; scope = spectrumAnalyzer(SampleRate=wave.SampleRate,... ViewType="spectrum-and-spectrogram"); data = []; for ii = 1:250 x = wave() + 0.05*randn(1000,1); scope(x); if scope.isNewDataReady data = [data;getSpectrumData(scope)]; end end release(scope);

R2022a: Support for dsp.SpectrumAnalyzer object will be removed

The isNewDataReady function will stop supporting the dsp.SpectrumAnalyzer object in a future release. Use the spectrumAnalyzer object instead.