Giancarlo asked . 2020-12-31

PWELCH vs PSD

I am trying to update some code that uses the deprecated function PSD to use PWELCH instead; however, I am getting completely different results when I am using what seems to be the same parameters. Does anyone know why? Here are what I believe to be the equivalent function calls:

   [pxx,f] = pwelch(data, hanning(1024), [], 1024, 250);
   [pxx,f] = psd(data,1024,250,hanning(1024));

Where: data = signal in a vector

   hanning(1024) = window vector
   1024 = nfft, number of points in the fft
   250 = Fs, the sampling rate
   [ ] = noverlap, defaults to 50% window overlap

Matlab has removed all help information for the PSD function, and instead says to use its functional equivalent pwelch, so I don't have anyway of looking up what the original documentation says about the function's inputs and outputs. Could the outputs be scaled differently? Is the PSD calculated differently between the two functions?

matlab , PWELCH vs PSD

Expert Answer

Neeta Dsouza answered . 2024-12-21 16:36:45

The result of psd is not correctly scaled, therefore you should use pwelch. For spectral density, the result should be scaled by the sampling frequency, which is not performed by psd.

If you look at the two results, the f vector should be the same. If you take the ratio of two pxx, you can that most samples, the differ by a factor of 125, which is basically half of sampling frequency. This is because the resulting spectrum is one-sided. The two end points differs by a factor of 250. This is due to the fact that these two points correspond to DC and Nyquist frequency and should not be doubled even if it's one-sided.

BTW, for your case, there is really no overlap happening because your data and window length are the same.

Not satisfied with the answer ?? ASK NOW

Recent Matlab Projects

Classification of Covid and Non-Covid Lungs CT-Scan using Deep Learning with MATLAB

Matlab simulation on Wind Energy system

Frequently Asked Questions

MATLAB offers tools for real-time AI applications, including Simulink for modeling and simulation. It can be used for developing algorithms and control systems for autonomous vehicles, robots, and other real-time AI systems.

MATLAB Online™ provides access to MATLAB® from your web browser. With MATLAB Online, your files are stored on MATLAB Drive™ and are available wherever you go. MATLAB Drive Connector synchronizes your files between your computers and MATLAB Online, providing offline access and eliminating the need to manually upload or download files. You can also run your files from the convenience of your smartphone or tablet by connecting to MathWorks® Cloud through the MATLAB Mobile™ app.

Yes, MATLAB provides tools and frameworks for deep learning, including the Deep Learning Toolbox. You can use MATLAB for tasks like building and training neural networks, image classification, and natural language processing.

MATLAB and Python are both popular choices for AI development. MATLAB is known for its ease of use in mathematical computations and its extensive toolbox for AI and machine learning. Python, on the other hand, has a vast ecosystem of libraries like TensorFlow and PyTorch. The choice depends on your preferences and project requirements.

You can find support, discussion forums, and a community of MATLAB users on the MATLAB website, Matlansolutions forums, and other AI-related online communities. Remember that MATLAB's capabilities in AI and machine learning continue to evolve, so staying updated with the latest features and resources is essential for effective AI development using MATLAB.

Without any hesitation the answer to this question is NO. The service we offer is 100% legal, legitimate and won't make you a cheater. Read and discover exactly what an essay writing service is and how when used correctly, is a valuable teaching aid and no more akin to cheating than a tutor's 'model essay' or the many published essay guides available from your local book shop. You should use the work as a reference and should not hand over the exact copy of it.

Matlabsolutions.com provides guaranteed satisfaction with a commitment to complete the work within time. Combined with our meticulous work ethics and extensive domain experience, We are the ideal partner for all your homework/assignment needs. We pledge to provide 24*7 support to dissolve all your academic doubts. We are composed of 300+ esteemed Matlab and other experts who have been empanelled after extensive research and quality check.

Matlabsolutions.com provides undivided attention to each Matlab assignment order with a methodical approach to solution. Our network span is not restricted to US, UK and Australia rather extends to countries like Singapore, Canada and UAE. Our Matlab assignment help services include Image Processing Assignments, Electrical Engineering Assignments, Matlab homework help, Matlab Research Paper help, Matlab Simulink help. Get your work done at the best price in industry.