In Table 3.2 a list of common Fourier transform pairs is given, which includes the pairs that were derived in this chapter.

3.8

APPLICATION TO SIGNAL MODULATION AND DEMODULATION

To illustrate the use of the Fourier transform, in this section an introduction is given to the transmission of information in the form of a signal generated by a source) over a channel and the reception of the information by a user. The channel may consist of free space or a cable. A key component of the transmission process is the use of modulation to convert the signal source into an appropriate form for transmission over the channel. In the modulation process, some parameter of a carrier signa based on the signal that is being transmitted. There are two basic types of modulation: analog and digital. In analog modulation the parameter being varied can take on a continuous range of values, whereas in digital modulation the parameter takes on only a finite number of different possible values. After transmission over a channel