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Autocorrelation and the case of the missing fundamental

Allen DowneyAllen Downey January 21, 201610 comments

A short hands-on exploration shows why we perceive the fundamental pitch even when it's absent from the spectrum. Using saxophone recordings, high-pass filtering, and autocorrelation plots, the post demonstrates that the highest ACF peak often predicts perceived pitch rather than the strongest spectral line. The experiments also show that removing high harmonics eliminates the effect, and that autocorrelation is a useful but incomplete model of pitch perception.


Generating pink noise

Allen DowneyAllen Downey January 20, 20161 comment

This post implements a stochastic Voss-McCartney pink-noise generator in Python, tackling why incremental per-sample algorithms do not map well to NumPy batch operations. It presents a practical NumPy/Pandas approach that uses geometric-distributed update events and pandas' fillna for column-wise zero-order hold to make batch generation efficient. The generated noise shows a power-spectrum slope near -1, matching expected 1/f behavior.


Differentiating and integrating discrete signals

Allen DowneyAllen Downey December 14, 20152 comments

Think DSP's new chapter digs into discrete differentiation and integration, using first differences, convolution, and FFTs to compare time and frequency domain views. The author reproduces diff via convolution then explores cumsum as its inverse and runs into two puzzling mismatches: noisy FFT amplitude ratios for nonperiodic data, and a time-domain convolution that does not reproduce cumsum for a sawtooth despite matching frequency responses. The post includes IPython notebooks and invites troubleshooting.


More free Ebooks

Sami AldalahmehSami Aldalahmeh September 13, 20112 comments

I found this website that contains loads of free, high quality, ebooks and journals as well. There is 176 ebooks under electrical engineering heading. I found books suitable for engineers, researcher, and hobbiest as well.

Here is the link for it:

http://www.intechopen.com/

To be more useful here are few MATLAB books:

http://www.intechopen.com/books/show/title/applications-of-matlab-in-science-and-engineering


Generating pink noise

Allen DowneyAllen Downey January 20, 20161 comment

This post implements a stochastic Voss-McCartney pink-noise generator in Python, tackling why incremental per-sample algorithms do not map well to NumPy batch operations. It presents a practical NumPy/Pandas approach that uses geometric-distributed update events and pandas' fillna for column-wise zero-order hold to make batch generation efficient. The generated noise shows a power-spectrum slope near -1, matching expected 1/f behavior.


Differentiating and integrating discrete signals

Allen DowneyAllen Downey December 14, 20152 comments

Think DSP's new chapter digs into discrete differentiation and integration, using first differences, convolution, and FFTs to compare time and frequency domain views. The author reproduces diff via convolution then explores cumsum as its inverse and runs into two puzzling mismatches: noisy FFT amplitude ratios for nonperiodic data, and a time-domain convolution that does not reproduce cumsum for a sawtooth despite matching frequency responses. The post includes IPython notebooks and invites troubleshooting.


Autocorrelation and the case of the missing fundamental

Allen DowneyAllen Downey January 21, 201610 comments

A short hands-on exploration shows why we perceive the fundamental pitch even when it's absent from the spectrum. Using saxophone recordings, high-pass filtering, and autocorrelation plots, the post demonstrates that the highest ACF peak often predicts perceived pitch rather than the strongest spectral line. The experiments also show that removing high harmonics eliminates the effect, and that autocorrelation is a useful but incomplete model of pitch perception.


More free Ebooks

Sami AldalahmehSami Aldalahmeh September 13, 20112 comments

I found this website that contains loads of free, high quality, ebooks and journals as well. There is 176 ebooks under electrical engineering heading. I found books suitable for engineers, researcher, and hobbiest as well.

Here is the link for it:

http://www.intechopen.com/

To be more useful here are few MATLAB books:

http://www.intechopen.com/books/show/title/applications-of-matlab-in-science-and-engineering