Bandwidth is the difference between upper and lower frequencies in a continuous band. Measured in hertz (Hz). Any band of given width can carry same information regardless of location
Multiplexing combines multiple signals into one over shared medium. Originated in telegraphy in 1870s, developed by George Owen Squier in 1910. Divides communication channel capacity into logical channels
Amplifier increases signal magnitude using electric power. Amplifier is a two-port circuit with power gain greater than one. Can be separate equipment or internal circuit within another device
FFT computes Discrete Fourier Transform of sequences or its inverse. Converts signals from time/space to frequency domain. Direct computation from definition is too slow. FFT reduces complexity from 30 million to 30,000 operations
SNR measures signal power relative to background noise power. Ratio greater than 1:1 indicates more signal than noise. Affects performance of communication, audio, radar, and imaging systems
Signal is a function that conveys information about a phenomenon. Signals can be any quantity that varies over space or time. Signals are important in signal processing, information theory and biology