Resolution Bandwidth, Spectrum analyzer

Hi everbody, i have a signal in workpace. i want to input the dsp. and to display on spectrum analyzer. After that, i must calculate the resolution bandwith value in this case. But i dont known how import to 'dsp' this signal. in advanced thanks

Answer 1

[Shubham]

Hi Erkan,

To analyze a signal in MATLAB using the DSP System Toolbox, you can use the dsp.SpectrumAnalyzer object to visualize the spectrum of your signal. Here's a step-by-step guide on how to import your signal into the DSP environment and display it on a spectrum analyzer, as well as calculate the resolution bandwidth (RBW):

Step 1: Load or Define Your Signal

First, ensure that your signal is loaded into the MATLAB workspace. This signal can be a vector or an array representing the time-domain data.

% Example: Create a sample signal (sine wave + noise)
Fs = 1000; % Sampling frequency in Hz
t = 0:1/Fs:1-1/Fs; % Time vector
signal = sin(2*pi*50*t) + 0.5*randn(size(t)); % Signal with noise

Step 2: Create a Spectrum Analyzer Object

Use the dsp.SpectrumAnalyzer object to visualize the spectrum of your signal.

% Create a Spectrum Analyzer object
spectrumAnalyzer = dsp.SpectrumAnalyzer('SampleRate', Fs, ...
                                        'PlotAsTwoSidedSpectrum', false, ...
                                        'Title', 'Spectrum Analyzer', ...
                                        'YLimits', [-120, 20], ...
                                        'ShowLegend', true);

Step 3: Stream the Signal to the Spectrum Analyzer

To display the signal on the spectrum analyzer, you can stream the signal data to the analyzer in a loop or directly input the entire signal if it's already available.

% Stream the signal to the spectrum analyzer
spectrumAnalyzer(signal);

% Release the spectrum analyzer (optional, if you need to modify settings)
release(spectrumAnalyzer);

Step 4: Calculate the Resolution Bandwidth (RBW)

The resolution bandwidth is determined by the settings of the spectrum analyzer, particularly the frequency resolution. In the DSP System Toolbox, the RBW can be inferred from the frequency resolution, which depends on the FFT length and the sample rate.

% Get the frequency resolution
fftLength = spectrumAnalyzer.FFTLengthSource; % 'Auto' or specific value
if strcmp(fftLength, 'Auto')
    fftLength = 1024; % Default value if 'Auto' is used
end

frequencyResolution = Fs / fftLength; % Frequency resolution in Hz
rbw = frequencyResolution; % Resolution bandwidth is typically equal to frequency resolution

fprintf('Resolution Bandwidth (RBW): %.2f Hz\n', rbw);