Telecommunications pervade our daily lives. Many people wake up to their radio alarms, open the TV to get traffic and weather updates, and perhaps telephone their car pool buddies just to make sure they won’t miss the ride. At the office, they boot their computers to check if they have emails or some other business documents delivered. All these are forms of telecommunications, and it is obviously something that no modern society can do away with.
Telecommunications actually rests on very simple elements –a sender or transmitter, a medium or channel, and a receiver. It is the transmitter that converts the message or data into electrical impulses or signals. These are carried away from the transmitter on a medium, which could be copper wires, optical fibers, or the free space channel. A receiver then copies the electric signal and converts it back into the same form it was entered into the transmitter.
A simple illustration of this is a radio broadcasting station that uses a power amplifier to convert music into electrical signals which are sent up to an antenna. The antenna interfaces with the free space channel using light propagation. The electric signal is caught by the antenna of a radio tuned to the same frequency and is sent to the receiver where it is converted back into vocal or musical sounds.
Because your radio can only receive signals from the radio station, the communication is termed one-way or simplex. Your cell phone, however, because it can receive as well as send out signals, is a two-way or duplex device. It is alternatively referred to as a transceiver. Systems that involve multiple transmitters and receivers, such as those used by the police, are called multiplex systems.
The transmission of signals from radio to TV stations, because it is sent from one powerful transmitter to a multitude of radio or TV sets, is termed broadcast telecommunications. That between two cell phones, on the other hand, is called point-to-point telecommunications.