Effective Communication Systems: Types, Technologies, and Methods
Communication: An Introduction
Communication is the transmission of information from one place to another. In terms of technology, communication requires a system with a message sender and a receiver.
The communication channel is the means by which the message is transmitted. Transmission occurs through environmental perturbations (signals) that originate in the transmitter until they reach the receiver. Key features include:
- The means by which it is transmitted (atmosphere, water, vacuum, optical fiber, etc.).
- The signals characteristic of the channel, transmission speed, bandwidth, interference, and maximum distance at which the signal arrives.
- The sender and receiver systems.
When information is conveyed to a large number of people away from us, it is network communication.
Signal Types
Signals are disturbances of the medium used by the channel.
- Analog Signals: The disturbances vary continuously over time (e.g., volume changes).
- Digital Signals: The perturbations are not continuous; the value taken at a given time has no relation to the value at the previous time.
Transmission Systems
- Wired: Achieved through physical connections between the sender and receiver systems.
- Wireless: Achieved through unchannelized means (water, atmosphere, etc.), using electromagnetic waves.
Transmission Media
The media are the cables, and the signal carries electrical information.
- Cables: Twisted pairs, used in fixed telephony, have two copper wires that transmit electrical signals.
- Coaxial Cable: Formed by a copper core that transmits the signal, with separate insulation and a copper or aluminum mesh that protects it from electrical interference. Used to transmit signals from the antenna to the TV.
- Fiber Optic: Can send signals several miles away, allows higher transmission speeds, and avoids electromagnetic interference. The core is formed by pure glass, which also has an outside jacket for protection. The sending system sends the signal from a laser or LED, and the receiver is covered by a photodiode.
Telephony
The telephone and the telegraph had three problems: they were slow to respond, could not receive the full message, and not everyone could use them. The telephone consists of:
- Microphone: Consists of a flexible membrane that vibrates with sound waves transmitted through the air. The vibration produces a state change in an electrical component that produces an electrical signal by varying the current.
- Receiver: Collects the electrical signal and reproduces the changes in a metal membrane, which is attracted and repelled continuously, reproducing the original sound.
- Central Phone: Where the operator located the teams responsible for controlling the flow of calls, including switching equipment. They are responsible for the connection between subscribers, sending tones and the voltage supply lines. Types:
- Analog: Using relays.
- Electro-analog: Use integrated circuits and analog-digital converters (second-generation plants).
- Digital: Using integrated circuitry (chip).
Antennas
Antennas are devices responsible for converting electromagnetic waves into electrical impulses (reception) and back (transmission).
Electromagnetic waves propagate through space at the speed of light and are characterized by their frequency.
Radio Modulation
Radio frequency signals, when captured by a receiver, result in unintelligible noise. To convey messages, the audio signal is mixed with the radio frequency signal, which then becomes the carrier of the message (modulating signal).
- Amplitude Modulation (AM): Uses a wave’s amplitude to carry the audio; the extent of the carrier frequency changes while the frequency remains constant.
- Frequency Modulation (FM): The frequency of the wave changes in amplitude and frequency of audio; the carrier amplitude remains constant.