1.Short Distance wireless media.
The short distance wireless media can support transmission within a rang covering a few meters up to a few miles/kilometers.
(a) Infrared
use of this type of transmi garage doors, wireles transmission media.
e of transmission uses infrared light to send data. You can see the this type of transmission in everyday life - TV remotes, automotive doors, wireless speakers etc., all make use of infrared as
infrared light transmits data through the air and can propagate
ughout a room (bouncing off surfaces), but will not penetrate walls. he infrared transmission has become common in PDAs (Personal digital esistants) e.g., hand held devices like palm pilots etc. The infrared transmission is considered to be a secure one.
(b) Laser
The laser transmission requires direct line-of-sight. It is unidirectional like microwave, but has much higher speed than microwaves. The laser transmission requires the use of a laser transmitter and a photo-sensitive Forever at each end. The laser transmission is point-to-point transmission, typically between buildings. But lasers have a certain disadvantage, which is : laser transmission can be adversely affected by weather. (c) Bluetooth Bluetooth is a telecommunications industry specification that describes how mobile phones, computers and personal digital assistants (PDAs) can be easily interconnected using a short-range wireless connection. Using this technology, users of cellular phones, pagers and personal digital assistants can buy a three-in-one phone that can double as a portable phone at home or in the office, get quickly synchronized with information in a desktop or notebook computer, initiate the sending or receiving of a fax, initiate a print-out, and, in general, have all mobile and fixed computer devices be totally coordinated. Bluetooth requires that a low-cost transceiver chip be included in each device. The transceiver transmits and receives in a previously unused frequency band of 2.45 GHz that is available globally (with some variation of bandwidth in different countries).
(d) Wi-Fi
Wi-Fi refers to Wireless Fidelity, which lets you connect to the Internet without a direct line from your PC to the ISP. For Wi-Fi to work, you need:
2. Long distance Wireless media .
The long distance wireless media can support communication over a longer distance upto thousands of kilometres. Long distance wireless communication media include :
(a) Microwave
Microwave signals are used to transmit data without the use of cables, similar to that of radio and television signals, but at different frequency range. It is line-of-sight transmission, which means the signal travels in a straight line free of material obstacles.
(b) Radio Wave
The transmission making use of radio frequencies is termed as radio-wave transmission. Radio Frequencies are in the range of 300 kHz to 10 GHz.
(c) Satellite
Radio wave can be classified by frequency and wavelength. When the frequency is higher than 3 GHz, it is named microwave. Satellite communication is special case of microwave relay system. Satellite communication use the synchronous satellite to relay the radio signal transmitted from ground station. In satellite communication the earth station consists of a satellite dish that functions as an antenna and communication equipment to transmit and receive data from satellites passing overhead. A number of communication satellites, owned by both governments and private organisations, have been placed in stationary orbits about 22,300 miles above the earth's surface. These satellites act as relay stations for communication signals. The satellites accept data/ signals transmitted from an earth station, amplify them, and retransmit them to another eart station. Using such a setup, data can be transmitted to the other side the earth in only one step.
The short distance wireless media can support transmission within a rang covering a few meters up to a few miles/kilometers.
(a) Infrared
use of this type of transmi garage doors, wireles transmission media.
e of transmission uses infrared light to send data. You can see the this type of transmission in everyday life - TV remotes, automotive doors, wireless speakers etc., all make use of infrared as
infrared light transmits data through the air and can propagate
ughout a room (bouncing off surfaces), but will not penetrate walls. he infrared transmission has become common in PDAs (Personal digital esistants) e.g., hand held devices like palm pilots etc. The infrared transmission is considered to be a secure one.
(b) Laser
The laser transmission requires direct line-of-sight. It is unidirectional like microwave, but has much higher speed than microwaves. The laser transmission requires the use of a laser transmitter and a photo-sensitive Forever at each end. The laser transmission is point-to-point transmission, typically between buildings. But lasers have a certain disadvantage, which is : laser transmission can be adversely affected by weather. (c) Bluetooth Bluetooth is a telecommunications industry specification that describes how mobile phones, computers and personal digital assistants (PDAs) can be easily interconnected using a short-range wireless connection. Using this technology, users of cellular phones, pagers and personal digital assistants can buy a three-in-one phone that can double as a portable phone at home or in the office, get quickly synchronized with information in a desktop or notebook computer, initiate the sending or receiving of a fax, initiate a print-out, and, in general, have all mobile and fixed computer devices be totally coordinated. Bluetooth requires that a low-cost transceiver chip be included in each device. The transceiver transmits and receives in a previously unused frequency band of 2.45 GHz that is available globally (with some variation of bandwidth in different countries).
(d) Wi-Fi
Wi-Fi refers to Wireless Fidelity, which lets you connect to the Internet without a direct line from your PC to the ISP. For Wi-Fi to work, you need:
2. Long distance Wireless media .
The long distance wireless media can support communication over a longer distance upto thousands of kilometres. Long distance wireless communication media include :
(a) Microwave
Microwave signals are used to transmit data without the use of cables, similar to that of radio and television signals, but at different frequency range. It is line-of-sight transmission, which means the signal travels in a straight line free of material obstacles.
(b) Radio Wave
The transmission making use of radio frequencies is termed as radio-wave transmission. Radio Frequencies are in the range of 300 kHz to 10 GHz.
(c) Satellite
Radio wave can be classified by frequency and wavelength. When the frequency is higher than 3 GHz, it is named microwave. Satellite communication is special case of microwave relay system. Satellite communication use the synchronous satellite to relay the radio signal transmitted from ground station. In satellite communication the earth station consists of a satellite dish that functions as an antenna and communication equipment to transmit and receive data from satellites passing overhead. A number of communication satellites, owned by both governments and private organisations, have been placed in stationary orbits about 22,300 miles above the earth's surface. These satellites act as relay stations for communication signals. The satellites accept data/ signals transmitted from an earth station, amplify them, and retransmit them to another eart station. Using such a setup, data can be transmitted to the other side the earth in only one step.
