ABSTRACT
In Chapter 1, we introduced various types of communication systems such as satellite, cellular, submarine, and fiber-optic cable networks. Systems like coaxial, submarine cable, and fiber optics use wired channels for transmitting signals, while cellular and satellite systems use wireless channels. The signals going through these wired or wireless transmission channels are quite complex, and it is important to understand their time and frequency content to design efficient transmission and receiver systems. For example, if we know that a particular signal is centered at 92.5 MHz (the frequency of a popular FM station), then we can use a band-pass filter to extract this signal.
