Telecommunications

Telecommunication, often called telecom, is the way we send information over long distances using electricity or electronic tools. We can do this through wires, radio waves, or other special technologies. These tools let us send many messages at once over one connection.

In the past, people used metal wires to send signals for things like the telegraph and telephone. Then, new ways to send messages without wires were invented. One famous inventor, Guglielmo Marconi, helped create radio.

Today, we use many digital tools to send not just voice but also data. Because wires have limits, we now use thin glass fibres that can carry light to send information. The Internet has made it easier for people all over the world to connect.

Definition

Telecommunication means sending information over a distance using electrical or electronic methods, like wires or radio waves. The word "telecommunication" was created in 1904 by a French engineer. It mixes a Greek word for "far off" and a Latin word for "to share." This shows it is about sharing information from far away.

History

Further information: History of telecommunication

Many ways to send messages over long distances have been used throughout history, from smoke signals, beacons, semaphore telegraphs, signal flags, and optical heliographs to wires and empty space made to carry electromagnetic signals.

Before the electrical and electronic era

Long ago, people found clever ways to talk over distances before electricity was discovered. Homing pigeons were used by many cultures. The Romans used them to send messages, and even Julius Caesar used them during battles. In the 1800s, a man named Paul Julius Reuter used pigeons to fly stock prices between cities.

Beacons were also used, with fires lit on hills to send messages like "the enemy is coming." In 1792, a French engineer named Claude Chappe built a system of towers where operators used flags to send messages between Lille and Paris.

Telegraph and telephone

Main articles: Telegraphy and Telephony

In 1837, two inventors, William Fothergill Cooke and Charles Wheatstone, showed the first electrical telegraph. Later, Samuel Morse made his own version and created a special code to send messages.

The first telephone was created by Alexander Bell in 1876. Soon after, the Bell Telephone Company began setting up phone services in cities like New Haven and London.

Radio and television

Main articles: Radio and Television

In 1894, Guglielmo Marconi began working with radio waves to send messages without wires. By 1901, he showed that radio could cross the Atlantic Ocean. After World War I, radio became popular for news and entertainment.

In 1925, John Logie Baird showed the first way to send moving pictures, which led to the creation of television.

Vacuum tubes

Main article: Vacuum tube

Vacuum tubes are special glass devices that help control electric currents. They were very important for early radios, televisions, and computers. Later, smaller and better parts called transistors replaced vacuum tubes.

Computer networks and the Internet

Main articles: Computer network and Internet

In 1940, a scientist named George Stibitz used a teletype machine to send math problems to a computer in New York and get the answers back. In the 1960s, new ways to send information in pieces were developed, leading to the creation of the Internet.

Growth of transmission capacity

The ability to send information around the world grew very fast. By 2007, the amount of information sent every day was huge, showing how important telecommunications became for the world.

Technical concepts

Modern telecommunication is based on important ideas that have developed over more than a century.

Basic elements

Telecommunication uses either wired or wireless methods. Every telecommunication system has three main parts:

• A transmitter that changes information into a signal
• A transmission medium, or physical channel, that carries the signal (like the "free space channel")
• A receiver that changes the signal back into information

In a radio broadcasting station, the large power amplifier is the transmitter, and the antenna sends the signal. The free space channel carries the signal, and the receiver’s antenna picks it up. The radio receiver then changes the signal into sound.

Some systems, like mobile phones, work both ways. They use a single device that acts as both transmitter and receiver, called a transceiver. These devices carefully separate their powerful transmission parts from their very sensitive receiving parts to avoid interference.

Analogue versus digital communications

Communications can use analogue or digital signals. Analogue signals change smoothly, while digital signals use discrete values, like ones and zeroes. Digital signals are better at handling noise, which can disturb analogue signals.

Communication channels

The word channel has two meanings. It can mean the physical path that carries the signal, like the atmosphere for sound, optical fibres for light, or coaxial cables for electricity. It can also mean a part of a larger channel used to send different streams of information at the same time.

One way to share a channel is by using different frequencies, called frequency-division multiplexing. Another way is by using different time slots, called time-division multiplexing (TDM).

Modulation

Modulation changes a signal to carry information. It can turn digital messages into analogue waveforms, or move low-frequency analogue signals to higher frequencies for better transmission. Common methods include amplitude modulation (AM) and frequency modulation (FM).

Telecommunication networks

A telecommunications network is a group of transmitters, receivers, and communications channels that send messages to each other. Digital networks use routers to direct information, while analogue networks use switches to connect users. Repeaters can strengthen signals over long distances. Digital systems also make it easier to store information.

Societal impact

Telecommunication has a big effect on society, culture, and the economy. Companies use it to grow and do business all over the world. For example, Amazon.com and big stores like Walmart have benefited from better phone and internet services. People in places like Bangladesh and Côte d'Ivoire use phones to sell their goods at better prices.

Good telecommunication services can help countries grow. However, not all countries have the same access to these services. This is called the digital divide.

Telecommunication changes how people connect with each other. Phones were first used for business, but later they became important for staying in touch with family and friends. Today, social networking sites let people chat and share photos. Before these sites, short message service and phones helped people arrange meetups.

Telecommunication has changed how we enjoy music and movies. Now, people can watch films at home on television and listen to music on the radio or internet. It has also changed how we get news, with most people in the United States getting their news from TV or radio instead of newspapers.

Regulation

Many countries have rules to manage telecommunication and broadcasting. These rules follow guidelines set by the International Telecommunication Union (ITU). This group helps countries agree on how to use radio frequencies so they don’t interfere.

There have been discussions and laws about balancing different types of communication, like printing and radio broadcasting. During World War II, many groups used radio to share messages. Today, debates continue about topics like managing broadband Internet service, stopping unwanted phone spam, and making sure everyone can afford to connect online.

Modern media

Telephone

In a telephone network, switches connect people who want to talk to each other. These switches create a link between the two users. When you dial a number, the switches make this connection. Your voice turns into an electrical signal using a small microphone in your handset. This signal travels through the network to the other person, where a speaker turns it back into sound.

Most home landline phones use analogue technology, where your voice changes the signal. But phone companies often change these signals to digital for long distances. Digital signals stay clear, unlike analogue signals which can get noisy.

Mobile phones have changed telephone networks a lot. Now, in many places, more people use mobile phones than landlines. Mobile phones often use digital systems, which are better than older analogue systems.

Radio and television

Main articles: Radio, Television, and Broadcasting

In broadcasting, a tower sends out waves carrying audio or video information. Receivers, like your radio or TV, pick up these waves. A device called a demodulator then gets the audio or video signal.

The broadcast industry is moving from analogue to digital signals. Digital signals don’t have problems like snowy pictures that analogue signals can have. This is because digital signals break information into clear pieces.

There are three main digital TV standards: ATSC, DVB, and ISDB. All use MPEG-2 for video compression. In radio, most countries use the Digital Audio Broadcasting standard, except the United States, which uses HD Radio.

Internet

The Internet is a worldwide network of computers that talk to each other using the Internet Protocol (IP). Every computer on the Internet has a unique IP address. This address helps other computers send messages to it. The Internet lets any computer send a message to any other computer using these addresses.

The Internet works because of protocols, which are rules that computers follow to talk to each other. These protocols are organized in layers.

The Internet can use many types of connections, like wired or wireless. For long-distance communication, it often uses optical fibres. At the network level, IP addresses help route messages. The World Wide Web uses the Domain Name System to turn addresses like Google into IP addresses.

Most internet communication uses TCP or UDP. TCP makes sure every message arrives safely, while UDP is faster. Both use port numbers to direct messages to the right application, like a web browser. Protocols keep data private when it travels between computers. Common internet activities include web browsing, email, file transfer, chat, and file sharing.

Voice over Internet Protocol (VoIP) lets voice calls travel as data packets.