Signal and Systems

This chapter provides a mathematical foundation for the analysis of signals, noise, and linear signal systems. The delta function plays an important role to develop theories of the Fourier analysis and to analyze signal and systems. The chapter discusses the energy, power, and their spectral densities of signal, and describes the correlation function and orthogonal signal. In radio communications, most of the noise is added to the signal in the radio channel and at the receiver. The noise that occurs at the transmitter hardly deteriorates the signal transmission quality, because the signal level is sufficiently high. Signal processing circuits are described with an emphasis on continuous time linear systems. The discrete-time signal is considered to be a special case of analog signal in a sense that it is produced from the analog signal through sampling. The chapter also discusses the optimum solution for signal system and adaptive signal processing techniques.