Undefined variable "dspdata" or class "dspdata.psd

I'm trying to run the matlab sample problem below (<http://www.mathworks.com/help/signal/ref/dspdata.psd.html?searchHighlight=psd)>, but am getting the undefined variable 'dspdata' or class 'dspdata.psd' error. This is in 2013b and I have the statistics tool box installed per check using the 'ver' command.

Fs = 32e3; t = 0:1/Fs:2.96; x = cos(2*pi*t*1.24e3)+ cos(2*pi*t*10e3)+ randn(size(t)); nfft = 2^nextpow2(length(x)); Pxx = abs(fft(x,nfft)).^2/length(x)/Fs;

% Create a single-sided spectrum Hpsd = dspdata.psd(Pxx(1:length(Pxx)/2),'Fs',Fs); plot(Hpsd); Undefined variable "dspdata" or class "dspdata.psd".

Answer 1

[Prateekshya]

Hello Jay,

The reason behind this error is the unavailability of dspdata class in your MATLAB environment. This could be due to several reasons, such as missing toolboxes or changes in the MATLAB API over different releases. However, you can calculate and plot the power spectral density (PSD) using alternative methods available in MATLAB. Here's how you can do it with pwelch, which is a part of the Signal Processing Toolbox:

% Sample rate and signal
Fs = 32e3;
t = 0:1/Fs:2.96;
x = cos(2*pi*t*1.24e3) + cos(2*pi*t*10e3) + randn(size(t));

% Compute the power spectral density using pwelch
[pxx, f] = pwelch(x, [], [], [], Fs);

% Plot the PSD
plot(f, 10*log10(pxx))
xlabel('Frequency (Hz)')
ylabel('Power/Frequency (dB/Hz)')
title('Power Spectral Density')
grid on

Kindly make sure you have the Signal Processing Toolbox installed and available in your MATLAB environment. You can verify this by typing ver in the MATLAB command window and checking for the Signal Processing Toolbox in the list.

I hope this resolves your query!