Radio

Communication

Communication represents the exchange of messages between at least two individuals, of which one emits (expresses) information and the other receives (understands), provided that the partners know the code (speak the same language). The instrument of communication in this case is language.
Considering that sound waves are significantly attenuated by the environment, verbal communication cannot be achieved over long distances. Thus, people were compelled to seek methods of transmitting information over distances through signs:

  • In the year 400 B.C., the transmission of information along the Great Wall of China was accomplished through light signals, using fire. Later, around the year 200 BCE, a more complex language was developed using flags, and by the years 618-907, a message could be transmitted over 2000 km in 24 hours;
  • The optical telegraph or the semaphore telegraph, invented in the year 1792, is a telegraph (tele – at a distance, graph – writing) that was invented by the Frenchman Claude Chappe; moreover, the word/term 'Telegraph' and 'Semaphore' were also coined by him.
The optical telegraph
The_optical_telegraph
  • The electric telegraph. The first devices used electrostatic discharges. Such a device was invented in 1866 by Sir Francis Ronalds, who offered the invention to the British Admiralty but was rejected as being useless. The electrostatic telegraph was abandoned in favor of the electromechanical one (with electromagnets). The first experiments with this type of telegraph were conducted by Baron Pavel L'vovitch Schilling in 1832, who established a telegraph line between Kronstadt and Peterhof Palace in Saint Petersburg. This system was abandoned upon his death in 1837. The vast majority of telegraph systems used multiple wires, and in 1837, Americans Samuel Morse and Alfred Lewis Vail invented the telegraph that uses a single wire for transmitting information and Morse code.
The telegraph key Telegraph
Telegraph_Key Telegraph
  • The wireless telegraph emerged after the discovery of radio waves (Hertzian waves), on which the German Heinrich Rudolf Hertz conducted various experiments published between 1886 and 1888. Thus, at the end of 1894, the Italian inventor Guglielmo Marconi began working on the idea of using radio waves to transmit information instead of a conductive wire. His demonstrations successfully transmitted information using Morse code over a distance of 6 km. Later, in 1899, information was transmitted across the English Channel, and in 1901, the first transmission was achieved across the Atlantic Ocean.