Three areas of telecommunications
Telecommunication includes the transmission, emission, or reception of signs, signals, writing, images, sounds, or information of any kind by wire, radio, optical, or other electromagnetic systems. This introduction describes three technical areas. Each one handles a different stage of transferring information.
- Processing technique (signal conversion): This stage converts the original information, such as a spoken word or a typed letter, into a signal suitable for transmission. The signal can be electrical, optical, or radio-based.
Examples: a microphone converts sound waves into an electrical signal. A computer keyboard converts a keypress into digital data. - Transmission technique (teletransmission): This covers sending a signal from the sender to the receiver through a transmission medium. It can take place in two main ways:
- Wired transmission: The signal travels through a physical medium, such as a copper cable, including twisted pair or coaxial cable, or a fiber-optic cable carrying light pulses.
- Wireless transmission: The signal is sent via electromagnetic waves propagating through space, such as radio waves, microwaves, or infrared.
- Switching technique (network switching): This area covers forwarding information and, for connection-oriented switching, establishing, maintaining, and terminating connections between users or devices within a larger network. Switching directs information to its intended destination.
Examples: telephone exchanges connect calls, and Internet routers direct data packets to the correct computer.
Teletransmission chain
The complete path from an information source to its destination is called the teletransmission chain. It consists of several components arranged in sequence. Each component has a defined role in transferring the message.
Teletransmission chain from information source to destination
- Information Source: Where the message originates (e.g., a person speaking, a computer sending a file).
- Transmitter (processing unit): Converts the original message into a primary signal and may further process it, for example by modulating or encoding it, to prepare it for transmission.
- Transmission channel: The physical medium, such as a cable, air, or fiber optic, through which the signal travels. At this stage the signal is exposed to noise, such as interference from other devices, and distortion caused by the channel's properties.
- Receiver (processing unit): Captures the distorted and noisy signal, processes it, for example by amplifying, demodulating, or decoding it, reconstructs the primary signal, and converts it into a message understandable by the recipient.
- Information Destination: The target for the information (e.g., a person listening, another computer).
Telecommunications in society
Modern society uses this infrastructure for Internet access, mobile communications, cloud computing, financial systems, and public safety. Understanding telecommunications principles supports the design and operation of scalable, secure, and efficient networks used today and developed for future needs.