Signals and systems

Signals and systems

Information is the one transmitted via communication. It may be very simple message like “yes” or “no”. It can be huge and complex message, such as he files containing the book or a television broadcast of a movie. It doesn’t matter if the “information” doesn’t contain anything a critic might agree was “information”.

A signal transmits that information. Signals may take many forms, such as optical, acoustic, electronic or radio-frequency. Signals may be converted from one form into another and still contain the same information. When we make a long-distance telephone call, the sound waves from our mouth are converted to an electrical signal at the telephone, that electrical signal is converted to optical form at the telephone switching office, back to electrical form at the local switching office on the other end and back to sound waves at the other person’s telephone.

A system is the equipment that performs a task, like transmitting signals. We often speak of telephone system as if it is the whole network of telephone equipment from our phone to the high-capacity fiber-optics cables that carry long-distance calls. However, parts of the telephone system also may be called systems, such as a switching systems that directs phone calls. We can assume a system which is a collection of stuffs designed to work together.

Basic components of data communication system

A data communication system is made up of five components.

i) Message

ii) Sender

iii) Receiver

iv) Medium

v) Protocol

Message - the message is the information to be communicated

Sender – The sender is the device that sends the data message. It can be computer, workstation, telephone etc.,

Receiver – The receiver is the device that receives the message. It can be a computer , workstations, telephone, fax machine

Medium – The transmitting medium is the physical path by which a message travels from sender to receiver . It can consists of twisted pair wire, coaxial cable, fiber optic cable or radio waves.

Protocol – A protocol is a set of rules that govern data communication. It represents an agreement between the communicating devices. Without a protocol two devices may be connected but not communicating , just as a person speaking German cannot be understood by a person who speaks only Russian.