Signal: The signal is an electromagnetic or light wave that represents data.
Signals are used to transfer data from one device to another through a communication channel.
In data, communication signals are used to send the data from one location to another. The signal is electromagnetic or light ways which carry out the data .one of the most important example is the signal transmission between different locations. The simplest form of signal is a direct current (dc) that is switched on and off. This is the principle by which the early telegraph worked. In telephony, a signal is special data that is used to set up or control communication
Classification of signals
The signal can be classified as
- Electrical signal
- Optical signal
- Electromagnetic signal
When electrical events serve to communicate information between two points these signals are called electrical signals. For example variations in voltage, current, frequency, etc. In simple wording, we sat that the electrical signal is a way of transferring the information through the use of electricity which carries the message. There are many types of electrical signals such as analog, digital. Microphones fax machines thermocouples remote controls for television sets are some of the examples of electrical signals.
Optical (light) is an advanced technique in which data are travel by means of electric voltage over the optical fiber.
The electromagnetic signal is sinusoid waves. Electromagnetic signal build with two components one is electric energy (sinusoid ) and other is magnet wave which is just perpendicular to the electric wave. Electromagnetic signal travel through the free space, as in wireless networking
Types of signal
There are two types of signal
- Analog signal
- Digital signal
The analog signal is a continuous electrical signal in the form of a wave.
- Simple analog signal
- Composite analog signal
1) simple analog signal: -
a sine wave cannot be decomposed into a simple signal. The sine wave is the most fundamental form.
2) composite signal: -
Many useful waveforms do not change in the smooth curve b/w a maximum and minimum amplitude (height of signal). Irregular consistent cycle after a cycle is called a composite signal.