Telecommunication Evolution: From Telegraph to Internet
Telecommunication: Bridging Distances Through Technology
Information and Communication
Information is the processed data that provides knowledge. Communication is the process of transmitting information between a sender and a receiver, which can be unidirectional or bidirectional (e.g., reading, watching TV). The communication process involves:
- Issuer: The source of information.
- Message: The data or information itself.
- Code: The representation of the information.
- Channel: The medium through which information is transmitted.
- Receiver: The recipient of the information.
Early Telecommunication: Telegraph and Telephone
Telegraph
The telegraph was the first telecommunication device with widespread implementation, enabling long-distance message transmission through electrical wires, initially, and later via electromagnetic waves (Marconi, 1901). It used a circuit with two symbols (dot and dash) to convey information.
Telephone
Alexander Graham Bell introduced the first telephone in 1875, allowing sound communication over an electrical cable. The telephone arrived in Barcelona in 1877. The telephone system is based on bidirectional sound transmission by converting sound into electrical signals at the transmitter, transmitting them through a network, and converting them back to sound at the receiver. There are two main types of telephones: fixed and mobile.
- Fixed Telephony: Telephones are located in a specific place (home, office) and connected to a communication network via a cable.
- Microphone: Converts sound into an electrical signal.
- Headset/Earpiece: Converts the electrical signal back into sound.
- Audible Ringer: An electronic sound that alerts the user to incoming calls.
Mobile Telephony
Mobile phones are autonomous devices that move with the user. They connect to the network via electromagnetic waves. Mobile telephony is an evolution of using electromagnetic waves for communication between a mobile device and a fixed relay station connected to the conventional telephone system. These devices connect to call centers via antennas distributed across the territory, forming a communication network between mobile phones and landlines. These cells transmit and receive signals within the cell and to a central computer that manages network traffic.
Fax
Fax technology transfers copies (facsimiles) of documents using devices operating on the conventional telephone network. Fax transmission is nearly instantaneous, but its low quality has led to email becoming the preferred method for electronic document transmission.
Radio and Electromagnetic Waves
Radio
Radio transmits signals by modulating electromagnetic waves with frequencies below visible light. Information is carried by systematically changing wave properties like amplitude, frequency, or phase.
Electromagnetic Waves
These waves propagate in space with electrical and magnetic components oscillating perpendicular to each other and the direction of propagation. Electromagnetic radiation types vary depending on frequency: radio waves, microwaves, infrared radiation, visible light, ultraviolet, X-rays, and gamma radiation. Electromagnetic radiation carries energy and momentum.
Television
Television is a system for broadcasting and receiving moving images and sound. Commercial television began in the 1930s and has become a ubiquitous appliance. Video recording equipment emerged 70 years later (VHS, DVD). Television is synonymous with post-modern culture. The TV receives and decodes television signals. A monitor lacks these circuits. Besides analog television, there are formats like closed-circuit television (CCTV), digital television, and high-definition television (HDTV).
- Microphone: Converts sound into an electrical signal for the modulator.
- Modulator: Combines audio frequency and carrier wave signals.
- CCD (Charge-Coupled Device): Measures photons in a matrix to generate a digitized image. Used in digital video and photo cameras, and telescopes.
Networks and Internet
Network Types
- Narrowband Networks: Transmit data at a few thousand bits per second (kbps).
- Broadband Networks: Transmit data at millions of bits per second (Mbps).
Internet Communication
- Instant Messaging: Real-time message exchange using a network like the Internet.
- Electromagnetic Spectrum: The range of all possible electromagnetic waves.
- TCP/IP Protocol: Identifies computers on a network with a unique number and divides information into packets for transmission.
- VoIP (Voice over Internet Protocol): Enables cost-free conversations between telephones connected to the Internet.
- Wi-Fi: Bidirectional communication system using radio frequency.
- Bluetooth: Data exchange between mobile devices over short distances.
- Parabolic Antennas: Reflect and concentrate waves into a focal point.
Order of technologies: sound, telegraph, telephone sets, phone, fax, radio, television, internet.