Analytic signal & Hilbert transform (FFT) — Matlab/Python envelope
Build the analytic signal with Hilbert or FFT, extract envelope and instantaneous phase/frequency — Matlab, Python, and an interactive Hilbert demo.
Sampling Theorem
Sampling in Matlab and downsampling an audio file
Generating a continuous signal and sampling it at a given rate is demonstrated here. In simulations, we may require to generate a continuous time signal and convert it to discrete domain by appropriate sampling. For baseband signal, the sampling is straight forward. By Nyquist Shannon sampling theorem, for faithful reproduction of a continuous signal in … Read more
Bandpass sampling (undersampling) — allowed fs zones, Matlab/Python demo
Bandpass / IF undersampling: choose sampling rates inside allowed zones so the replica does not alias — with formulas and a live bandpass sampling demo.
The Nyquist-Shannon Sampling Theorem
Nyquist–Shannon sampling for baseband signals: sample faster than twice the highest frequency, or aliases fold into band.