Telecommunication |
Telecommunication refers to Communication over long distances. In practice, something of the message may be lost in the process. Telecommunication covers all forms of distance and/or conversion of the original Communications, including radio, telegraphy, television, telephone, data communication and computer networking.
The elements of a telecommunication system are a transmitter, a medium (telephone line) and possibly a channel imposed upon the medium (see baseband and Broadband as well as multiplexing), and a receiver. The transmitter is a device that transforms or encodes the message into a physical phenomenon; the signal . The transmission medium, by its physical nature, is likely to modify or degrade the signal on its path from the transmitter to the receiver. The receiver has a decoding mechanism capable of recovering the message within certain limits of signal degradation. Sometimes, the final receiver is the human eye and/or ear (or in some extreme cases other sensory organs) and the recovery of the message is done by the brain (see psychoacoustics.)
Telecommunication can be point-to-point, point-to-multipoint or broadcasting, which is a particular form of point-to-multipoint that goes only from the transmitter to the receivers.
One of the roles of the telecommunications engineer is to analyse the physical properties of the telephone line or transmission medium, and the statistical properties of the message in order to design the most effective encoding and decoding mechanisms.
When systems are designed to communicate through human sensory organs (mainly those for vision and hearing (sense)), physiological and psychological characteristics of human perception must be taken into account. This has important economic implications and engineers must research what defects can be tolerated in the signal and not significantly degrade the viewing or hearing experience.
= Examples of human (tele)communications =
In a simplistic example, consider a normal conversation between two people. The message is the sentence that the speaker decides to communicate to the listener. The transmitter is the language areas in the , and the language areas in the listener s brain that will decode the signal into meaningful information and filter out background noise.
All channels have noise . Another important aspect of the channel is called the bandwidth. A low bandwidth channel, such as a telephone, cannot carry all of the audio information that is transmitted in normal conversation, causing distortion and irregularities in the speaker s voice, as compared to normal, in-person speech.
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