Power and energy of a signal — formulas, classification, and examples
Energy Ex = Σ|x|² vs power Px as a long-window average of |x|²; energy signals vs power signals; physical scaling by load Z; Python examples and links to Matlab verification.
Power spectral Density
White noise in Matlab — generate, analyze, and measure power
How to simulate white noise in Matlab, check spectrum and power, and relate AWGN variance to SNR — with links to AWGN generation and BER tools.