These are usually older electronic gadgets (before 1990’s). Analog systems handle information which is represented by continuous change and flow, such as voltage or current. Analog devices have dials and sliding mechanisms. Analog signals itself looses the strength of signal while making copies or after long time. A good example of an analogue signal is the loud-speaker of a stereo system. When the volume is turned up the sound increases slowly and constantly. Other examples of analogue systems include; Old radios, megaphones and the volume control on old telephone handsets.
The digital signal represents the data in discrete units (the binary digits 1 and 0). Modern electronic products such as computers and mobile phones depend on digital signals. Digital circuits are the most common mechanical representation of Boolean algebra and are the basis of all digital computers. In most cases the number of states is two, and these states are represented by two voltage levels: one near to zero volts and one at a higher level depending on the supply voltage in use. These two levels are often represented as “Low” and “High.” A good example of a digital signal is Morse code. The signal is sent as a series of ‘on’ and ‘off’ pulses. The signal is either present or it is not.
A logic gates are an elementary building block of a digital circuit. They are the complex circuitry of number of transistors and resistors. Most logic gates have two inputs and one output. At any given moment, every terminal is in one of the two binary conditions low means 0(zero) or high 1(one), represented by different voltage levels. In most logic gates, the low state is approximately zero volts (0 V), while the high state is approximately five volts positive (+5 V).