Lecture
This lecture covers the basics of signals, frequencies, and bandwidth, starting with the definition of a signal as a function, examples like sound waves and electromagnetic waves, pure sinusoids with amplitude, frequency, and phase, sum of sinusoids, Fourier theory, frequency measurement units, and the importance of bandwidth in signal processing. It also discusses the spectral representation of a signal using Fourier analysis, where the horizontal axis represents frequencies and the vertical axis represents amplitudes.