isNewDataReady

Check spectrum analyzer for new data

Syntax

flag = isNewDataReady(scope)

Description

flag = isNewDataReady(scope) indicates whether or not the spectrum analyzer scope displays new spectrum estimates. When you are logging spectrum analyzer data from the dsp.SpectrumAnalyzer scope, use this function to ignore duplicate spectrums from the getSpectrumData function.

Examples

Log Spectrum Data

While a 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 = 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);

In the data table, you can see gaps in the simulation time. These 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 =

  5x4 table

    SimulationTime       Spectrum           Spectrogram       FrequencyVector
    ______________    _______________    _________________    _______________

         [1]          [1536x1 double]    [100x1536 double]    [1536x1 double]
         [3]          [1536x1 double]    [100x1536 double]    [1536x1 double]
         [4]          [1536x1 double]    [100x1536 double]    [1536x1 double]
         [6]          [1536x1 double]    [100x1536 double]    [1536x1 double]
         [7]          [1536x1 double]    [100x1536 double]    [1536x1 double]

Input Arguments

scope — Spectrum analyzer

System object name

Spectrum analyzer that you want to save data from.

Output Arguments

flag — New data flag

true | false

true

The spectrum analyzer shows new data.

false

The spectrum analyzer shows the same spectrum as the last time the scope was called.