Understanding Telecommunications: From Wireline to GPS

Posted on Jan 31, 2025 in Electronics

Wireline and Wireless Communication

Wireline: Requires a physical medium for sending information.

Wireless communication: Does not require a physical medium.

When to Use Interference-Shielded Cables

Interference-shielded cables are used repeatedly when there is a need to minimize external interference.

Cost Comparison

Cable systems are generally more expensive than wireless systems.

Ubiquity of Wireless Systems

The great advantage of wireless systems is their ubiquity.

Telephone Operation

  1. When speaking, emitted sound waves affect the microphone.
  2. These waves vibrate a membrane that is linked to a piezoelectric crystal.
  3. These crystal current variations produce an electrical signal.
  4. The electrical signal is transmitted by a cable until it reaches the telephone exchange.
  5. Telephone exchanges connect two people who want to talk by telephone.
  6. The signal is sent from the switchboard to the receiver’s mast.
  7. Another piezoelectric crystal is located in the receiver.

Telephony Networks

A set of interconnected elements to transmit and receive voice between sites.

Two Systems

  • Analog: Voice is transmitted directly, and electrical impulses are transmitted through a medium.
  • Digital: A major advance, offering higher quality and reliability with the signal source. It can generate a number of added services.

Telephony and Data Services

SMS, EMS, MMS, video calls, video messages, web browsing, chat, and news.

Security in Data Transmission

  • The first generation of mobile telephony was analog.
  • In the second generation of mobile telephony, voice transmission is digital.
  • The third generation (3G) of phones uses IP technology to transmit data.

Method of Key Pairs

  • Public Key: One key is published if it can be distributed worldwide so that encrypted messages can be sent to us.
  • Private Key: Only known to us.

Protection of Mobile Terminals

  • SIM Card: A small printed circuit needed to connect the terminal to the telephone network.
  • PIN: A 4-digit number to activate the terminal.
  • PIN2: A code to access special services.
  • PUK: A code to unblock the SIM card.
  • IMEI: A unique 15-digit code associated with the phone, used by operators to identify their terminals on the network.

Radio

A wireless medium that can transmit sounds. It utilizes the transmission of radio waves, from which it takes its name. Electromagnetic waves communicate in space without physical support.

How a Radio Communication System Operates

  1. A microphone transmitter captures the sound, and the signal varies according to the incident sound; this is called modulation.
  2. The final signal is emitted by an antenna.
  3. Radio waves propagate through space.
  4. A receiver, via an antenna, receives the radio signal that travels through space.
  5. Demodulation occurs.
  6. That signal is directed to a loudspeaker where it is heard.

Television

A system for transmitting images and sounds through electromagnetic waves, including radio waves.

How Luminophores Turn On and Off

  • Electron Gun: Incidents on the screen and turns on the light points.
  • Plasma TV: A small quantity of gas in each luminophore.
  • LCD Screens: Each luminophore is covered by liquid crystal, which may become transparent.

Emission and Reception of Radio and Television

Analog Broadcasting: Maximum coverage until 2010, one-way system, variable reception quality.

Digital Transmission: New broadcast stations and new receivers, associated services, more emissions, improved reception quality, and wider bandwidth.

Radio and Television Services

  • Teletext: Textual information pages.
  • Guide Plus: Programming guide included on DVD recorders.
  • RDS: Sends information in parallel to voice and music.
  • Digital Services: Information, entertainment, and access to banking.

Applications of the GPS System

Exact location, layout of paths and navigation, surveillance, digital mapping, and traffic routes.

CD

Made it possible to store sound in digital format on a disk. The sound quality is superior to traditional vinyl, and it does not degrade with successive hearings.

DVD

Better picture quality, no wear, eight different sound tracks, excellent sound quality, direct access, and cheaper.

MP3 Players

Internal memory, DVD players in the living room, and internal hard drives.