A complete, single telecommunications circuit consists of two stations, each equipped with a transmitter and a receiver. The transmitter and receiver at any station may be combined into a single device called a transceiver. The medium of signal transmission can be via electrical wire or cable (also known as “copper”), optical fiber, electromagnetic fields or light. The free space transmission and reception of data by means of electromagnetic fields is called wirelesscommunications.
Types of telecommunications networks
The simplest form of telecommunications takes place between two stations, but it is common for multiple transmitting and receiving stations to exchange data among themselves. Such an arrangement is called a telecommunications network. The internet is the largest example of a telecommunications network. On a smaller scale, examples include:
- Corporate and academic wide-area networks (WANs)
- Telephone networks
- Cellular networks
- Police and fire communications systems
- Taxi dispatch networks
- Groups of amateur (ham) radio operators
- Broadcast networks
Data is transmitted in a telecommunications circuit by means of an electrical signal called the carrier or the carrier wave. In order for a carrier to convey information, some form of modulation is required. The mode of modulation can be broadly categorized as either analog or digital.
In analog modulation, some aspect of the carrier is varied in a continuous fashion. The oldest form of analog modulation is amplitude modulation (AM), which is still used in radio broadcasting at some frequencies. Digital modulation actually predates analog modulation; the earliest form was Morse code. Modern telecommunications use IPs(internet protocols) to carry data across underlying physical transmissions.
Telecommunications service providers
Telecommunications systems are generally run by telecommunications service providers, also known as communications service providers. These providers historically offered telephone and related services and now offer a variety of internet and WAN services, as well as metropolitan area network and global services.
In many countries, telecom service providers were primarily government owned and operated, but that is no longer the case, and many have been privatized. The International Telecommunication Union is the United Nations agency that administers telecommunications and broadcasting regulations, although most countries also have their own government agencies to set and enforce telecommunications guidelines. In the United States, the Federal Communications Commission is the primary regulatory agency.
Within the large umbrella of companies that provide different types of telecommunications services are internet service providers, wireless service providers, radio and television broadcasters, cable companies, satellite television providers and managed service providers.
The word telecommunications comes from the Greek prefix tele, which means distant, combined with the Latin word communicare, which means to share.