Communication Channels

Communication Channels are a fundamental element of whole communication system. The data is carried from one computer to another by these channels which are divided into two categories. One is by providing a physical connection. The other category is wireless.

Physical connections: use a solid medium. Here are some kinds of  it. 
1. Twisted-pair cable: It consists of twisted-pair copper wire. It is used by standard telephone lines and Ethernet cables, commonly used in networks and to connect several components to the system unit. 

2. Coaxial cable: It replaces the multiple wires of twisted pair with a single solid-copper core. It has over 80 times the transmission capacity of twisted pair and it is used deliver TV signals to connect computers in a network , too. 

3. fiber-optic cable: It is used to transmit data as pulsations of light through teeny tube glasses. It has over 26,000 times the transmission capacity of twisted-pair cable. They transfer info. using rays of light at light speeds instead of electricity pulsations, making faster than copper cable. It is more reliable at transferring data than coaxial cable.

Wireless connections: use the air itself. Infrared, radio frequency, microwave and satellite are primary technologies used for wireless connections. 

1. Infrared: Infrared light waves are used to communicate over short distance. 

2. Radio frequency: Radio signals are used to communicate between wireless devices. Most business wireless networks are based on Wi-Fi ( wireless fidelity ). A short-range radio communication          ( Bluetooth ) transfers data up to about 33 feet. It is widely used for wireless headsets, printer connections and handheld devices.

3. Microwave: line-of-sight communication are provided by it because microwaves go in a straight line . the waves can be transmitted only over relatively short distance. however, it is good for sending data between buildings.

4. Satellite: satellites are used to orbit around 22,000 miles above the earth as microwave relay stations. They can relay microwave signals from one transmitter on the ground to another. they can be used to transfer large volumes of data. the main disadvantage of this communication is that bad weather can usually interrupt the flow of data. GPS ( Global positioning system ) is one of the most interesting applications of satellite communications. Its devices use location information, that sent to earth, to determine the geographical location of the device. this system is mounted into the dash with a monitor to display maps and speakers to provide spoken directions. GPS technology is used by many today`s cell phones for handheld navigation.