Radio communication, what is the principle of radio communication?
Radio communication, what is the principle of radio communication? A communication method that uses radio waves to transmit information. Can transmit sound, text, data and images. Compared with wired telecommunications, there is no need to set up a transmission line, which is not limited by the communication distance, and has good mobility and rapid establishment; but the transmission quality is unstable, the signal is easily interfered or intercepted, and the confidentiality is poor. The receiver rang the bell. When the assistant cut off the power of the electromagnetic wave generator, the electric bell stopped abruptly. Faced with the facts, those who supported him in the past, those who opposed him, and those who doubted him all stepped forward to shake hands and congratulate him. Since then Popov has improved his machine and replaced the bell with a telegraph. In this way, a complete radio receiver is formed. Three-Axis Micro DSLR Stabilizer is composed of pan axis, rolling axis and tilt-axis. With a gyro-stabilized gimbal system, it keeps stabilized or steerable horizon with automatic calibration to give you an unprecedented smooth shooting experience.
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[Edit this paragraph] The controversy about who invented in the UK, people regarded Maxwell as the pioneer of radio, thinking that he first pointed out the existence of electromagnetic waves.
In the United States, some people think that De Forest is the father of radio because he invented the triode, which is the heart of radio communication equipment.
In Russia, only Popov is recognized as the founder of radio communications.
In the eyes of Western scientists, the Italian Marconi was the inventor of radio communications, and he won the Nobel Prize in Physics for this.
In Germany, people think that Hertz is the pioneer of radio, because he first proved the existence of electromagnetic waves. The unit of the vibration frequency of electromagnetic waves is named after his surname.
Who invented radio communication? It can be considered that the invention of radio is the result of joint research by many scientists and the product of historical development.
[Edit this paragraph] History of invention After humans invented the telegraph and the telephone, the speed of information transmission is unknown how many times faster than before. The emergence of telegrams and telephones has shortened the sense of distance between people of all continents and countries. However, the original telegraphs and telephones used current to transmit signals in the wire, which made communication very limited. For example, to communicate, there must first be a line, and setting up the line is restricted by objective conditions. High mountains, big rivers, and oceans all bring great difficulties to the construction and maintenance of the route. Moreover, the sea ships that are in great need of communication and the aircraft that were invented later, because they are moving vehicles, cannot be connected with people on the ground by wire. The radio communication technology invented in the 19th century has made communication free from the way of relying on wires. It is a leap in communication technology and an important achievement in the history of human science and technology.
Those who succeed on the road to science are always the brave people who are always tireless, good at summing up the experience of their predecessors, and drawing lessons from their predecessors. Who can persevere, who suddenly burst out of inspiration, he can pick the fruits of victory. The Russian Popov and the Italian Marconi are such people.
Popov was born in a pastor's family in Russia in 1859. At the age of 18, he was admitted to the Department of Mathematics and Physics at the University of Petersburg. Soon transferred to the Forestry College. The active academic atmosphere of the Forestry College made him lay a solid foundation, and Popov graduated with excellent results a few years later. In 1888, Hertz discovered that electromagnetic waves had spread to Russia. The 29-year-old Popov suddenly changed his previous idea of ​​installing electric lights throughout Russia, and established the ideal to direct electromagnetic waves to fly all over the world. In 1894, Popov made a magnetic wave receiver. The principle of this machine is similar to that of the British scientist Rocky, but the sensitivity is much higher than that of Rocky.
Popov's outstanding contribution to radio communications was when he discovered the role of antennas. In one experiment, Popov found that the sensitivity of the metal chip detector was abnormally high. The distance to receive electromagnetic waves has increased significantly than usual. He didn't let go of this anomaly, carefully observed the surrounding environment, and found no changes. I found many reasons, but they all ruled out. He felt very strange, and tried again, the sensitivity was still unusually high. Suddenly, he glimpsed a wire on the geophone. Obviously, this wire increases the receiving capacity of the detector and increases the sensitivity. Popov was really overjoyed, improving the sensitivity of the machine and increasing the transmission and receiving distance. The wire he used was the first antenna in the world. Popov used this machine to first detect lightning. He connected the Morse telegraph to the machine. On a summer night with thunder and lightning, his receiver received the thunder in the air and recorded it with a note on the Morse telegraph.
On May 7, 1895, Popov brought the radio receiver he invented to the meeting place of the Physics Branch of the Russian Society of Physical Chemistry in Petersburg. After reading the paper, he made a demonstration on the spot. He asked his assistant to place the electromagnetic wave generator at the end of the lecture hall, adjusted the receiver on his podium, installed the antenna, and connected the relay and the bell to the receiver. When everything is ready, the assistant turns on the electromagnetic wave generator,
On March 24, 1896, Popov and his assistant performed another formal performance of Morse code transmission by radio. Popov placed the receiver in the conference hall of the Physical Society, and his assistant installed the transmitter in the Forestry College, about 250 meters away. When the time came, the assistant calmly transmitted the signal, and the receiver on Popov's side clearly received the signal. At this time, the branch president of the Russian Physics Society wrote the received letters one by one on the blackboard. Finally, a line of letters appeared on the blackboard: "Heinrich Hertz". This is the first radio telegram in the world, which commemorates Hertz, the discoverer of electromagnetic waves.
Marconi was born in Italy in 1874. His father is Italian, farm owner, and his mother is Irish. In 1894, the year of Hertz ’s death, Marconi had just turned 20. He read Hertz ’s experiment and Rocky ’s report in the Electrical Magazine. He has been fond of playing with coils and electric bells since he was a child, so he got into electromagnetic wave research. He thought that since Hertz can measure electromagnetic waves a few meters away, as long as there is a sufficiently sensitive detector, it will certainly be able to measure electromagnetic waves at a further distance. After many failures, he finally took a gratifying first step. He installed a device for emitting radio waves upstairs in his home, and placed a detector downstairs, which was connected to the electric bell. As soon as he turned on the power upstairs, the bell downstairs rang. At night, when his father saw this novel device, he threw the anger and dissatisfaction that had been held in his stomach out of Jiu Xiaoyun, and never called him "unrealistic daydreamer." And began to give financial assistance to his son, let him concentrate on experiments. After Marconi's first victory, confidence increased. He collected a lot of materials and articles, whether the authors of these wooden articles are famous or unknown, as long as they are useful and inspiring articles, he will read them patiently and analyze them carefully. He analyzed the shortcomings of each family clearly, gathered his strengths, and improved his own machine.
The next summer, Marconi completed another very successful experiment. In the autumn, the experiment made great progress. He unfolded a kerosene barrel and turned it into a large iron plate to serve as a transmitting antenna. Hang the receiver's antenna high on a large tree to increase the receiving sensitivity. He also improved Rocky's metal powder detector by adding a small amount of silver powder to the glass tube, mixing it with nickel powder, and then removing the air from the glass tube. As a result, the transmitter increases power and the receiver also increases sensitivity. He placed the transmitter on one side of a hill and the receiver in his home on the other side of the hill. When a signal was sent to his companion as an assistant, the receiver he was waiting for received the signal, driving the electric bell to make a clear sound. This sound is more pleasant to him than touching symphony. The distance of this experiment reached 2.7 kilometers.
In 1937, Marconi died, and nearly ten thousand people buried his funeral in Rome, Italy. At the same time, all British radiotelegraphs and radiotelephones, and the radio station of the British Broadcasting Association stopped working for 2 minutes to mourn this great man in the radio field . Although Marconi, Popov, and other scientists who have contributed to the field of radio communications have left the world, the radio communications they invented are left to future generations, and will benefit the children and grandchildren.
Tribute to great scientists!
Long live science!
Broadcast programs are sent at radio stations. The sound wave of the broadcast program is converted into an audio frequency electrical signal by an electroacoustic device and amplified by an audio amplifier. The oscillator generates a high-frequency constant amplitude oscillation signal; the modulator causes the high-frequency constant amplitude oscillation signal to be modulated by the audio signal; The frequency-frequency oscillating signal is amplified and sent to the transmitting antenna, where it is converted into radio waves and radiated out.
The reception of radio broadcast is realized by radio. The receiving antenna of the radio receives the radio waves in the air; the tuning circuit selects the signal of the required frequency; the detector restores the high-frequency signal into an audio signal (ie, demodulation); the demodulated audio signal is then amplified to obtain sufficient driving power ; Finally, the radio content is restored through electroacoustic conversion.
In summary, the transmission and reception of radio communication (broadcasting also belongs to the category of radio communication) can be summarized as the conversion process of three aspects that are opposite to each other, namely: transmitting information-low frequency signal, low frequency signal-high frequency signal, high Frequency signal an electromagnetic wave.
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