Data and Signals Information that is stored within computer systems and transferred over a computer network can be divided into two categories: data and signals. Data are entities that convey meaning within a computer or computer system. If you want to transfer this data from one point to another, either by using a physical wire or by using radio waves, the data has to be converted into a signal. Signals are the electric or electromagnetic encoding of data and are used to transmit data.

Converting Data into Signals Like data, signals can be analog or digital. Typically, digital signals convey digital data, and analog signals convey analog data. However, you can use analog signals to convey digital data and digital signals to convey analog data. The choice of using either analog or digital signals often depends on the transmission equipment that is used and the environment in which the signals must travel. There are four combinations of data and signals: digital data transmitted using digital signals, digital data transmitted using analog signals, analog data transmitted using analog signals, and analog data transmitted using digital signals. Data Comm. & Computer Networks, Second Edition 5
Spread Spectrum Technology Using a spread spectrum transmission system, it is possible to transmit either analog or digital data using an analog signal. However, unlike other encoding and modulation techniques, only an intended receiver with the same