The Three Pillars of Telecommunications

Any telecommunication system can be broken down into three fundamental areas of technique, each handling a different part of the information journey.

• Processing Technique (Signal Conversion): This initial stage involves converting the original information (e.g., a spoken word, a typed letter) into a signal suitable for transmission. This 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 the actual process of sending the signal from the sender to the receiver through a transmission medium. This can be achieved in two main ways:
  • Wired Transmission: The signal travels through a physical guide, such as copper cables (e.g., twisted pair, coaxial cable) or fiber optic cables (transmitting light pulses).
  • Wireless Transmission: The signal is sent via electromagnetic waves propagating through space (e.g., radio waves, microwaves, infrared).
• Switching Technique (Telecommutation): This area deals with establishing, maintaining, and terminating connections between users or devices within a larger network. Switching ensures that information is correctly routed to its intended destination.
  Examples: Telephone exchanges that connect phone calls, or internet routers that direct data packets to the correct computer.

The Teletransmission Chain

The complete path that information travels from source to destination is called the teletransmission chain. It consists of several key components that work in sequence to ensure the message gets through.

Teletransmission chain – from information source to destination

1. Information Source: Where the message originates (e.g., a person speaking, a computer sending a file).
2. Transmitter (Processing Unit): Converts the original message into a primary signal and may further process it (e.g., modulate, encode) for transmission.
3. Transmission Channel: The physical medium (e.g., cable, air, fiber optic) through which the signal travels. The signal is exposed to NOISE (e.g., interference from other devices) and DISTORTION (caused by the channel's imperfections) at this stage.
4. Receiver (Processing Unit): Captures the distorted and noisy signal, processes it (e.g., amplifies, demodulates, decodes) to reconstruct the original signal, and converts it back into a message understandable by the recipient.
5. Information Destination: The target for the information (e.g., a person listening, another computer).