Obtain Measurements Data Programmatically for Spectrum Analyzer Block
Compute and display the power spectrum of a noisy sinusoidal input signal using the Spectrum Analyzer block. Measure the cursor placements, adjacent channel power ratio, distortion, and peak values in the spectrum by enabling these block configuration properties:
CursorMeasurements
ChannelMeasurements
DistortionMeasurements
PeakFinder
Open and Inspect the Model
Filter a streaming noisy sinusoidal input signal using a Lowpass Filter block. The input signal consists of two sinusoidal tones: 1 kHz and 15 kHz. The noise is white Gaussian noise with a mean of 0 and a variance of 0.05. The sampling frequency is 44.1 kHz. Open the model and inspect the parameter values in the blocks.
model = 'spectrumanalyzer_measurements.slx';
open_system(model)
Access the configuration properties of the Spectrum Analyzer block using the get_param
function.
sablock = 'spectrumanalyzer_measurements/Spectrum Analyzer'; cfg = get_param(sablock,'ScopeConfiguration');
Enable Measurements Data
To obtain the measurements, set the Enabled
property to true
.
cfg.CursorMeasurements.Enabled = true; cfg.ChannelMeasurements.Enabled = true; cfg.DistortionMeasurements.Enabled = true; cfg.PeakFinder.Enabled = true;
Simulate the Model
Run the model. The Spectrum Analyzer block compares the original spectrum with the filtered spectrum.
sim(model)
The panes at the bottom of the spectrum analyzer window display the measurements that you have enabled.
Use getMeasurementsData
function
Use the getMeasurementsData
function to obtain the measurements programmatically.
data = getMeasurementsData(cfg)
data = 1x5 table SimulationTime PeakFinder CursorMeasurements ChannelMeasurements DistortionMeasurements ______________ __________ __________________ ___________________ ______________________ 9.9962 1x1 struct 1x1 struct 1x1 struct 1x1 struct
The values shown in the measurement panels match the values shown in data
. You can access the individual fields of data
to obtain the various measurements programmatically.
Compare Peak Values
As an example, compare the peak values. Verify that the peak values obtained by data.PeakFinder
match with the values in the spectrum analyzer window.
peakvalues = data.PeakFinder.Value frequencieskHz = data.PeakFinder.Frequency/1000
peakvalues = 27.0020 26.3150 -3.7436 frequencieskHz = 15.0015 1.0049 7.3500