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Radio

Topic: Inventions
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History

Early in our history was the only way to convey information and news by talking to each other. Some other ways were such as Indians who developed a way to communicate with each other by smoke signals. When man began to domesticate horses could travel longer distances in less time and could provide news faster via couriers who brought the news, and eventually got mail. Boat also became a way to travel on and which information could be disseminated via the travelers.

During the 1700s, developed the telegraph, which in the early 1840s, further developed by Samuel Morse. It came to mean much for the future. The Telegraph was able to both receive and send signals. It was widely used in the military and shipping to communicate.
Samuel Morse developed the telegraph which could receive and write down the codes on paper. The codes were dots and dashes representing a letter. The codes were called Morse alphabet.

1864 filed James Clerk Maxwell, a theory that there were electromagnetic waves, a form of radiation which he called radio waves.
Many years later proved Heinrich Hertz, a German physicist, the radio waves really exist. In 1888, he showed how these waves could be generated. He charged from a battery over a coil that was attached to two metal balls, which had a small gap between them. A few meters from the coil had fastened a wire and at each end of it there was a metal ball. When it lit a spark between the first two bullets so kindled it even it between the other two. Hertz then showed that the electromagnetic waves exist and that they moved through the air. 1890 waves could be detected at longer distances.

After Hertz and Maxwell came Edouard Branly. He invented a machine, kohären that could detect where there were radio waves somewhere.

The Italian Guglielmo Marconi began experimenting with Hertz previous discoveries. In 1894 he invented a transmitter that resembled kohären. With it, he could send a signal to a receiver that was in a room next to the transmitter.
Later, you could send signals reach over 3 kilometers.
While Marconi was researching Alexander Popov at the same thing. He succeeded even better and invented the first antenna. He realized that it was easier for the recipient to recognize signals if there was a wire connected to the antenna.
Popov was unable to continue researching because of lack of funds. Then used the Marconi Popov antenna to a receiver.
Italian state was not then interested to finance Marconi further work. The British were interested in his invention. In 1898 he traveled to England and received a patent for his invention.
Nikola Tesla questioned Marconi's patent for wireless radio, and after his death it was concluded finally that it was Nikola Tesla who invented the radio.
An English company tested his invention in a lighthouse, test precipitated very good. Then they tested to establish links between a station on shore and a ship, which also did well.

Karl Ferdinan Braun was working on with the inventions. In 1898 he changed the position of the discharge in the transmitter, so that it could transmit on different wavelengths. This facilitated so that sagging problem of all recipients received all signals were sent.
1909 got Braun and Marconi Nobel Prize in Physics.

But there was much more that could be improved. It was not always so convenient to just be able to send small short signals to each other. Lee De Forest constructed in 1907 electron tube which amplified radio signals, and it became an important beginning to be able to transmit speech and music through the radio. Some years later, after much work and wear from many scientists were able to transmit both voice and music through the radio.

Marconi was still running with their projects, and discovered that there were wavelengths never before exercised. You could transmit on a frequency that was higher than before, 100 Mhz, and called the VHF (Very High Frequency), and a lower than ever, called for VHF (Ultra Short Wavelength). They did not use the VHF much until 1936, when television became popular.
FM were many interested, Marconi succeeded best to develop it, and sent a message with speeches from London to Australia.

1918 Edwin Armstrong invented a receiver, who also received very weak signals. Eighteen years later, it was he who came up with frequency modulation, FM. Previously, only used amlitudmodulerade broadcasts, AM. The advantage of using FM was that lax disturbances such as bad weather and loud machinery. FM was a very useful discovery.

1922 began broadcasting radio in Sweden, which had, however, not many can afford to buy it. There was also a charge that you had to pay to have a radio. For those who could not afford to buy a radio or pay the fee, there were radio clubs where you could go and listen. 1925 took Radiotjänst over all radio transmission from the Swedish Radio and Telegraph Administration had begun broadcasting radio.
At the beginning of World War II, approximately 70% of Sweden's population have access to radio.

1947 developed the transistor and replaced the radio tube. The transistor was an electronic component intended to be used as amplifiers in radio.
1954 launched the first transistor radio. In early transistors could not handle high frequencies in an FM receiver and was therefore easily broken. Later, better transistors that could handle the FM frequencies.

How does the radio?

I've divided up some facts about the radio at various points, to show a little how the radio works.

The radio waves are waves that travel through the air and has the same speed as the speed of light.

Radio waves occur when a magnetic and an electric field varies at a rate that depends on the kind of wave that is about. Two such fields do you get when you let these electrical impulses going through an antenna. Are usually divided into wavebands in the top five major types: long wave, LV, medium wave, MW, shortwave, SW, VHF, VHF, and microwaves. The first four are used in broadcasts on radio, while microwaves are used in television broadcasts. Unlike sound waves, radio waves, not leading them, they go through the "thin air". Radio waves are measured in Hertz (after physicist), meaning the number of oscillations per second. The radio wave emitted from the transmitter is called the carrier, since it carries with it a message to the recipient. Inside, the radio wave is the information to be transmitted, stored in a manner that is called modulation. The most common varieties of modulation is FM and AM.

FM / AM are different types of frequencies that can transmit radio waves at. Thanks to that you can tune into their radios on different frequencies, you avoid receiving any audio that flows to the receiver.
To set the frequency on the radio there is a button, new radios, or a knob on older devices that you use to set the desired frequency.
FM stands for frequency modulation, or AM for amlitudmodulering.
The difference between FM and AM is that FM removes any noise that interferes with the transmission, such as weather, noisy machines and any noise from other frequencies. The advantage of AM is instead the signals to reach far longer than they do on FM.
The transmitter is the device that sends sound, speech and signals. In order to transmit speech is a microphone attached to it. All voice / sound going into the microphone are converted into electrical impulses, radio waves.
When radio waves travel, they have three different options to travel.
The first is to send high frequency (see image red line) allow the radio waves emitted and then bounce off the ionosphere and back.
The second is to send at a low frequency, because the waves are not disturbed by the mountains and the like that it encounters. Then you have to unfortunately have large antennas and the sound is not so good.
The third way is to send out radio waves to a satellite (see picture's blue line), which then sends them back to the place where they should be. It is a very good way, in addition to satellites cost a lot of money.
The receiver is the station or radio that will receive radio waves. For the receiver to intercept the radio waves, it has an antenna. Now everything works the other way around, the radio waves are transformed back into electrical impulses. Since the sound is weakened during his "journey", there is always an amplifier at the receiver, which is connected to a speaker.

The transistor replaced the radio tube in the fifties. The transistor was an electronic component that is used as an amplifier in the radio. The amplifier was designed to only let through radio waves but no noise.

Two other important components of the transmitter and receiver, the capacitor and the inductor.
The coil is a bit complicated. Around the coil, there are many turns of copper wire (see image 1.2). If one connects a current source to form a magnetic field around it, it becomes an electromagnet.
When removing the power source also vanishes magnetic field, but in the coil, it remains current.

The capacitor acts like a battery when you connect it to a power source, the capacitor up (see Figure 3). When you then disconnect the power source, power stays in the capacitor (see Figure 4).
If one connects the charged capacitor and inductor loaded all power over to the coil. Everything is very fast but the coil forms a magnetic field, but it disappears quickly. Then produced the current in the coil since its power source, the capacitor was broken. Stream formed in the coil returned to the capacitor and the capacitor passes its charge to the coil, and so on. For the whole thing to be able to continue, you have to continuously supply power to the capacitor, since part of the capacitor charging all the time lost during the process. The electric power exchanged between the coil and the capacitor is supplied to the oscillation circuit.

In the receiver, there is also an oscillation circuit. The oscillation circuit must be on the same frequency as the transmitter for it to work. Turning the knob changes the size of the capacitor. The kind of capacitor that you can resize called variable capacitor.
When you resize it, also change the frequency, and the current flowing to the oscillation circuit. In this way, the oscillation circuit just received the wavelengths that are at the same frequency as that.
The future of radio

The radio can not develop much except around what is already there, which improved sound and better reception. But the way to send radio waves can always be improved, and there are many ways to improve the way they are sent on. The only question is, how can you do it in the cheapest and best way, how to send radio waves anymore and how many people should be able to get access to the radio?
The target is enough to be able to receive signals from any location on Earth without it becoming virtually no interference, and be able to do it with a cheap radio that most should be able to afford to buy.

Felix Assarsson

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