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Telegraph
The first global communication system with the characteristics of today: insant communication, long distance and low price. It was the telegraph, developed by Samuel Morse in 1835. In its time it meant a breakthrough, compable to what the internet currently represents.
The telegraph had a transmitter and a receiver. A message could be emitted and received. To send a message, the button had to be manipulated to open and close the electrical circuit between the transmitter and the receiver. -
Morse code
The telegraph used the Morse code (the name is by the creator). A code that consisted of dots and stripes to represent the information. -
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The telegraph
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Multiplexing
The telegraph sparked new technologies such as multiplexing. It allowed to send several messages at once with only one cable. -
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Other inventions after the telegraph
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The true inventor of the telephone
Meucci is the true inventor of the phone, but could not patent it for financial reasons. He was the first person to manage to transmit the human voice at a distance through an electronic device. -
Telephone operation (part 1)
The membrane vibrates when speaking and compresses the granules. If they are close together, a lot of current will pass through the microphone and when they are separated, little current will pass.
The microphone manages to transfer the information that is in the sound by an electrical cable. Information that travels in the form of electricity is called an electrical signal. The signal will travel to the receiver. -
Telephone operation (part 2)
For this you need two copper cables and a current source, for example a battery. The current of current passes through the electromagnet. That attracts the metal membrane with more or less force (depends on the intensity). As the membrane moves, air particles also move around and the original sound is produced. -
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The telephone
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Submarine cable
Later, the submarine cable was invented. This made it possible to connect two continents (Europe and America). -
Radio
Radio is a telecommunication system that allows the transmission of signals at a distance through a type of electromagnetic waves, radio waves. -
Radio (discovery)
Its discovery dates back to 1867, the year in which the Scottish physicist J. C. Maxwell, investigating the properties of electricity and magnetism, proposed the theoretical existence of electromagnetic waves. This hypothesis was proved by H. R. Hertz, who in 1887 succeeded in generating electromagnetic waves and detecting them in a device located 30 cm from the emitter. -
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The telephone
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Telephone patenting
Another invention was the phone, which was invented by Meucci but patented by Alexander Graham Bell. -
Wireless telegraphy
Wireless telegraphy was also invented by Marconi. He used the discoveries of Maxwell and Hertz to build the first wireless communication system. He patented and commercially developed wireless telegraphy, a system that allowed messages to be sent in Morse code (dots and dashes) using radio waves. The most important moment of Marconi's research came in 1901, when he managed to transmit a message between Europe and America, the first long-distance wireless message. -
The transmission of sound and the commercial broadcast of radio
After wireless telegraphy, the next challenge was the transmission of sound, the radio we know today, which was invented by R. Fessenden in 1906. A few years later, in the 1920s, began commercial radio broadcasting in the United States and Europe. The radio quickly became popular. -
Emission and reception of television signals (Part 1)
There is a long process to watch a program. The image and sound is captured with a video camera and a microphone. The signals are sent to a sending unit, where they are processed and edited. The signal is transmitted in the form of electromagnetic waves through an antenna. -
Emission and reception of television signals (Part 2)
The waves are picked up by the receiving antenna which transforms into an electrical signal. The television receivers connected to the antenna have an electronic circuit that amplifies the electrical signal and transforms it back into image and sound. -
Hertz
The hertz (Hz) is the unit of the International System of Frequency Units. The hertz is a derived unit and is equivalent to 1/s, this means that it indicates the number of repetitions of a certain physical phenomenon that is repeated every second of time.
The name was established by the International Electrotechnical Commission. Later, when Hertz was established in the International System of Units, it was included as a unit of frequency derived from time. -
Television
Television is a telecommunication system that allows the remote transmission of sound and moving images, synchronized.
After being able to transmit sound through the invention of radio, the next step was to develop a system capable of transmitting images. The necessary technology was invented in the first decades of the twentieth century and is the work of numerous engineers,
Television broadcasts began in the 1930s. -
Types of televisions
There are different ways to transmit and receive a television signal. These forms are:
- Terrestrial television(an audiovisual signal is sent by electromagnetic waves from a transmitting antenna and received by the antennas of the houses)
- Satellite television(satellites located in space are repeaters located in space in Earth's orbit)
- Cable television(the signal comes through a fiber optic or coaxial cable)
- Internet television(uses computer networks so that the video reaches the viewer) -
Mobile phone
Martin Cooper is the creator of the mobile phone and the first person to call on a mobile phone. At first it was very expensive and only had executives from large companies that used them from the car. -
How the mobile phone works
By calling you will send a radio signal to the antenna of the cell where you are. To the base station the radio signal is transformed into an electrical signal that is sent to the mobile telephone exchange. The control panel then searches its database where the phone you are calling is located and redirects the signal to its cell. There the electrical signal is transformed into radio waves that are detected by the receiving telephone. -
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The mobile phone
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Commercial mobiles
The first commercial mobiles arrived in the United States and Japan.
