Radio

We explain what the radio is, its characteristics and how it works. In addition, we tell you how it was invented and which were the first stations.

What is radio?

Radio, also known as radio communication, It is a distance communication technology through the emission of electromagnetic waves that carry audio signals recoverable by means of a receiving device, known as a radio receiver or simply radio. The waves it uses are called Hertzian. Radio was the first technology that allowed sounds (such as music or the human voice) to be transmitted over long distances.

Every day, when we talk about “radio”, we may be referring to different, but related things:

• To the receiving device that allows us to tune in and listen to a station, that is, to a receiver.
• To the means of mass communication that consists of a network of stations that unidirectionally transmit different live or recorded programs, that is, to the broadcasting.
• The telecommunications system that allows two users to emit and receive sound signals in turns, through hertzian waves, that is, at radio communications.
• To the technology of sound transmission through Hertzian waves that allows the existence of the previous two, that is, to the radio.

The appearance of radio in the 20th century brought with it a great stir and countless applications: such as the ability to listen to music or the news while working, or quickly and effectively communicate soldiers with their rearguard in the middle of a military conflict. Until the massification of television and digital media in the second half of the century, radio was the largest mass medium on the planet, and it still survives today.

See also: Types of media

Invention and history of radio

The background to the invention of radio has to do with the understanding of the electromagnetic field by physicists of the British Royal Society of the 19th century, such as James Clerk Maxwell (1831-1879). Maxwell was the first to formulate a theory of how electromagnetic radiation works that is, the way in which electromagnetic waves propagate through the air.

Thanks to these discoveries, In 1888 the German physicist Heinrich Rudolf Hertz (1857-1894) demonstrated that these electromagnetic waves could be detected and created artificially, and designed a first model of wave emitters and receivers. In their honor and recognition, these types of signals are known today as waves. hertzians.

Based on these successful experiences, Italian inventor Guillermo Marconi (1874-1937) designed the first wireless telegraphy system which used Hertzian waves to send and receive impulses, so that they could be interpreted with Morse code. This invention was known as “wireless telegraphy” and He was the direct precursor of radio.

It is important to note, however, that similar inventions were developed in other latitudes, which is why Aleksandr Stepanovich Popov (1859-1906) in Russia and Nikola Tesla (1856-1943) are also recognized as inventors of radio in their respective countries. in the United States.

In the early years of the 20th century, The invention of the diode and the triode made it possible not only to detect electromagnetic waves but also to amplify them. Thus, the emission of short-distance waves and the production of receivers began to become much more frequent.

Until, shortly after, In December 1906, the first radio sound broadcast in history occurred: It was responsible for the Canadian scientist Reginald Fessenden (1866-1932), who transmitted half an hour of music and conversation openly, using a high-frequency electromagnetic alternator. That Christmas Eve, different recipients were able to hear him read passages from the Bible and play the violin.

That same year the word “radio” was introduced by the Berlin Radiotelegraph Convention, although the public (especially the Anglo-Saxon) preferred the use of wireless (“wireless”) to refer to this type of transmissions.

In the United States and other industrialized countries, in 1910 there were already different stations equipped with some type of own programming. The massification of radio and its transformation into a mass medium with a global presence took place gradually starting in 1920.

In the 1950s, furthermore, the invention of the transistor meant an enormous improvement in the construction of radio receivers. Radio alone ruled the mass media until 1948, the year television was invented.

First radio stations

The first radio stations were actually wireless telegraphy stations that is, they did not transmit sounds, but electromagnetic impulses. This changed in 1920, when the first public broadcasts for entertainment began and even more so in 1937, when FM (frequency modulated) band broadcasting began, with much higher quality and reach.

The first radio stations emerged in Europe and the United States, and operated privately and intermittently generally among radio amateurs. Some of them were WWJ 950 in Detroit, KDKA in Pittsburgh, and then large radio networks such as Westinghouse, the Radio Corporation of America (RCA), the National Broadcasting Company (NBC) and the Columbia Broadcasting System (CBS).

For its part, in Europe the British Broadcasting Company (BBC) emerged in England, Radio Ibérica in Spain, Radio Tour Eiffel and Radio PTT in France, among many others. In Latin America, the first radio stations emerged in Argentina, Colombia, Mexico, Uruguay, Chile, Cuba, Panama and Puerto Rico between 1920 and 1922.

Importance of radio in the world

Broadcasting brought with it an important change worldwide in telecommunications, since allowed the rapid and easy transmission of information over great distances. This had important repercussions in military matters, for example, since ships and other vehicles could communicate with each other or with the starting base and coordinate their strategic movements; but also in industrial and commercial logistics, since it allowed better coordination of trains and other freight vehicles.

On the other hand, for the first time in history, the possibility of communicating verbally with other human beings at a distance was materially possible. After the popularization of radio, numerous radio amateurs emerged throughout the world, communicating with their peers in the nearby geography (due to the short range of radio devices at that time) and receiving and commenting on signals from official institutions and organizations. No other technology had a similar impact on communication until the advent of the Internet at the end of the 20th century.

The radio soon became part of human daily life, accompanying workers on their day and drivers on the road, as it allowed them to listen to a program without having to occupy other senses. This is why the radio ushered in the era of mass communications in the world, that is, the possibility of addressing thousands or millions of people at the same time from a radio station. This represented new exploitable terrain in terms of advertising, information and entertainment.

How does the radio work?

Radio operates through the electromagnetic spectrum, that is, through the transmission of electromagnetic waves through space, which can be received by an electrical conductor (i.e., an antenna), to which they cause perceptible changes in electrical charge.

Thus, the radio transmitter (the station) artificially emits these electromagnetic waves and modulates them in a specific way, that is, modifies their properties, so that they transmit specific information. When a receiver (the radio device) receives them with its antenna, it is capable of demodulating them and recovering the information contained in the wave, for example, a human voice.

The receiving device, for its part, has an electrical circuit specially designed to filter and separate the current generated in the antenna, and subsequently amplify it selectively, finally sending it to a loudspeaker or speaker equipped with an electromagnet where this electric current is transformed into sound waves. Through a capacitor of variable capacity, the device allows the user to filter the different frequencies of the emitted waves, and thus choose between one or another radio emission.

This transmission can occur in two different ways:

• By amplitude modulation (AM) when the amplitude of the received waves varies. It is the easiest method to modulate and demodulate, which allows the construction of simpler and cheaper receivers, although with lower sound fidelity and lower power.
• By frequency modulation (FM) when the frequency of the received waves varies. With higher fidelity than AM and greater noise filtering capacity, it has been used not only for radio, but also for television and data.

Radio Features

In general terms, radio is characterized by the following:

• It is a mass media which allows recorded or live information to be transmitted to numerous receivers at the same time.
• Use Hertzian waves (electromagnetic) to conduct sound in different channels: air, water, even vacuum.
• It is a one-way means of communication since anyone who tunes in to a station can only receive auditory information, not respond to it in the same way. This is slightly different in the case of radio communications, since the sender and receiver can take turns sending and receiving messages, but they can do so only one at a time, not simultaneously.
• It uses different bands of the radio spectrum endowed with different features: low, medium, high frequency and very high frequency, for example. Likewise, there are two types of receivers: AM (amplitude modulated) and FM (frequency modulated).
• Radio waves are also used to transmit video (television), data (internet) and also for telephony. However, the name “radio” is only used for the transmission of sounds through that same channel.
• It should not be confused with the chemical element of the same name (Ra) nor with the geometric concept (half the diameter of a circle).

Continue with: Old media

References

• “Radio (media)” in Wikipedia.
• “Radio: concepts and functions” at the University of the Americas Puebla (Mexico).
• “The science behind the radio” in La Vanguardia.
• “How do radio and television work?” (video) at the Federal Telecommunications Institute (Mexico).
• “Radio (broadcasting)” in The Encyclopaedia Britannica.