Signals & Systems I: Cross-Correlation and Convolution

This lecture covers the definition of cross-correlation function, intercorrelation between complex or real signals, reversal operator, signal detection by thresholding, optimal detector in the presence of white noise, orthonormal basis representation, Hilbert spaces, orthonormal families of functions, orthogonal approximation theorem, and trigonometric Fourier series. It also discusses image compression using the Discrete Cosine Transform (DCT) and the spectrum of periodic signals.