The Origin and Development of Radio

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Prehistory of Radio (19th Century)

In 1820, this relationship was found, and in a very simple experiment, he proved that the current carried by the wire can deflect the magnetized compass. 183 1 year, he started a series of experimental electromagnetic induction, which was mathematically shaped by Faraday's law and later became one of the four major ones.

Faraday proposed that the electromagnetic force extend to the empty space near the headquarters, but did not finish his work to intervene in that proposal. The theoretical basis of electromagnetic wave propagation was first described in his paper in 1873 by an electromagnetic field dynamics theory of the Royal Society, which was experienced by David e. Hughes after his work between 186 1 year and 1865+0878. When he noticed the noise caused by the inductance balance in his receiver, 1880, he showed his findings to the Royal Society, but told him that it was only induction.

It was between 1886 and 1888 that Maxwell's theory was confirmed. Experiments show that radio radiation has all the products of waves (now called Hertzian waves), and it is found that electromagnetic equations can be reformed into partial differential equations called wave equations. Nathan Stubblefield, a farmer in Kentucky, invented the radio during the period of 1885- 1892, but his equipment seems to work beside inductive transmission instead of radio broadcasting.

Wireless starting point

At 1893 in St. Louis, Tesla publicly demonstrated "wireless" radio communication. Speaking at Franklin College in Philadelphia and the National Electrical Association, he described the principle of radio communication in detail. [1] The equipment he used contains all the components of vacuum tube before the development of integrated radio system. Tesla is an application mechanism of electronic conduction to wireless practice. In addition, he initially used a sensitive electromagnetic receiver [2], which is different from the less sensitive correlator used by Marconi and other early experimenters. Russian physicist Alexander? Popov celebrated the Alliance as "Radio Day" in Russia on May 7th, 1995/KLOC-0.

1896, Marconi obtained the British 12039 radio patent, which has been improved in the transmission of electronic pulses and signals and in the electrical appliances. Therefore, it is considered as the first radio patent in the world, although it uses various early technologies of Tesla, and popov has demonstrated similar instruments. Marconi established a radio station in 1897, and in the same year, Tesla applied for two key radio patents, 1900.u, and released them as soon as possible. S. The Patent Office overturned the judgment of 1904 and granted Marconi a patent for inventing radio, which may be influenced by Marconi's financial supporters, including Thomas Edison. The government avoided paying royalties to Tesla.

radiocommunication

After Tesla publicly demonstrated radio communication in 1893, the principle of sending signals by radio communication was widely publicized through space receivers. Telsa equipment contains all components of the radio system used before the development of vacuum tubes.

On August 19, 1894, the British physicist Mr. Oliver showed a received signal in Morse code, and sent out a radio wave signal with a detection device called a coherence meter. The pipeline was filled with waste Temistocle Calzecchi-Onesti from fermo, Italy, 1884. Edward Branly France and Alexander? Popov Kochler's Russian later led to an improved version. Popov developed a practical communication system according to Cohen's statement, which was widely regarded by his villagers as the inventor of radio.

Jagdish Chandra Bose, an Indian physicist, publicly demonstrated the use of radio waves in Kolkata at 165438+ 10/894, but he was not interested in applying for a patent for his work. [3] Bose is ignited by gunpowder, and the bell is rung by electromagnetic waves at a long distance, which proves that communication signals can be sent without wires. Bose attended a lecture tour to London in 1896 and met Marconi, who was doing wireless experiments for the British Post Office. Later, in 1899, Bose published "his invention and telephone detector for molten steel, silver and steel", which was introduced in a paper of the Royal Society of London.

1895, Marconi sent a message that there were no wires, but he didn't make a sound on the radio waves; Reginald Fessenden, 1900, finish that and send a weak signal. On Christmas Eve, 1906, Fei Sen used his heterodyne principle to transmit the first radio broadcast in history from Brandrock, Massachusetts. Ships at sea heard Fei Sen's song "Holy Night Broadcasting" and read a passage from the Bible.

1909, Marconi was awarded the Nobel Prize in Physics with him as "contribution to the development of wireless telegraph". However, Tesla's patent (No.645576) was restored to 1943 by the US Department of Justice. After his death, the Supreme Court. This decision is based on the fact that avant-garde art existed before Marconi's patent was created. Some people believe in this decision and allow you to join for economic reasons. S. The government avoided paying for the damage caused by the use of its patents during World War I (although these people ignored Tesla's avant-garde art).

Radio factory

Marconi opened a radio factory in Hall Street, chelmsford, England on 1898, with about 50 employees. At the nearby 1900, Tesla opened the Wardenclyffe tower facilities and advertising services. Starting from 1903, the tower structure is nearly completed. There are various theories about how Tesla intends to achieve the goal of this wireless system (it is reported that it is a 200 kW system). Tesla claims that Wardenclyffe, as a part of the transmitter world system, will allow secure multi-channel transmission of information, universal navigation, time synchronization and global positioning system.

The wireless telegraph is blank (1896–1920).

The first advantage of the Radio and Telecommunications Law is that it can establish communication between coastal radio stations and ships at sea. The company told Britain to set up Marconi and others. The company and its assistants have a monopoly position in Marconi Company in the United States to support on-board communication. It operated American telephone and communication machines until 1983, owned all its own equipment, and refused to communicate with non-Marconi companies to equip the ship. Many inventions have improved the quality of radios, and enthusiasts have experimented with the use of radios, thus sowing the first seeds of broadcasting.

The use of spark gap transmitters in wireless telegraphy has become very common. After the ship sank, the maximum RMS force was 19 12. The international conference was held for 19 13 safety of life at sea. The production treaty requires the ship's radio station to provide personnel 24 hours a day.

A typical powerful spark gap is a rotating commutator connecting each wheel, six to twelve, nine inches wide to one foot, which drove Volt DC about 2000 years ago. Because of the blank connection and disconnection, radio waves are audible, because the breath is concentrated in the crystal. When the telegraph key is made, the power supply of 2000 volts is often directly cut off. One side of the spark gap is directly connected to the antenna. Before blank transmitters were replaced by continuous wave transmitters, receivers and thermionic tubes became common.

Audio-visual broadcasting (19 15- gifts)

Invented vacuum tube detector, invented by Westinghouse electrical engineer. On Christmas Eve, 1906, Reginald Fei Sen (using his heterodyne principle) transmitted the first radio audio-visual broadcast from Brandt Rock, Massachusetts. Ships at sea heard the broadcast, including Silent Night played by Fei Sen on the violin and a passage read aloud.

The first known broadcast news program was broadcast, which started at 1920 (in the morning) by the 8MK radio station of the unlicensed predecessor WWJ. The entertainment regular radio broadcast of Laiter Research Center near chelmsford began at 1922. Early radios ran the full power of the transmitter through a carbon microphone.

When some early radios used certain types of amplification functions through current or batteries, the most similar receiver type in the mid-1920s was crystal collection. In the 1920s, the amplification vacuum tube revolutionized two kinds of radio receivers and transmitters.

The invention of triode amplifier, generator and detector made audio-visual radio possible. Invent the (morning) radio so that more than one station can send signals (as opposed to creating a blank radio, one transmitter reports the entire spectrum bandwidth), so as to transmit signals between Reginald and Lee? De forest.

The starting point of radio broadcasting

Charles. David Herrold, an electronic consultant in San Jose, California, set up a radio station on April 1909. It uses spark gap technology, but adjusts the carrier frequency according to human voice and the latest music. Residents' "San Jose Call" (no radio call sign) continued in intact offspring and eventually became KCBS of San Francisco today.

Herold, the son of farmer A in Santa Clara Valley, coined the terms "narrow broadcast" and "broadcast", respectively recognizing that transmission is destined to be a unique receiver, such as a receiver on a ship, and those transmissions are destined to be ordinary viewers. The use of "broadcasting" in agriculture defines the throwing of seeds in all directions.

Charles, when? Herod didn't claim to be a transmitter's voice, he claimed to be a "broadcaster". To promote the spread of radio signals in all directions, he designed an omnidirectional antenna, and he boarded the roofs of various buildings in San Jose. Herod also won the title and accepted it as the first broadcasting company, although advertisements usually involve paid announcements. He exchanged publicity for a local record store to play records at his residence.

Westinghouse Electric Company in Pittsburgh, Pennsylvania, obtained the radio call sign KDKA of10/0/0 1920, becoming the first commercial radio station in the United States. Their engineer frankly broadcast from his own station 19 16. E.W. Scripps' WWJ was in Detroit and claimed priority, but they didn't accept their business license until nearly a year later. Broadcasting has no advertising support. Radio stations are owned by manufacturers and department stores. Radio stations are sold and owned by newspapers. Newspapers are sold and owners' opinions are expressed.

Westinghouse was introduced into the Patent Alliance Group, American Telephone and Communication Machine and American Radio Company, and became the owner of RCA. All radios manufactured by GE and Westinghouse are sold by 60% GE and 40% Westinghouse under the RCA label. ATT western conference builds radio transmitter. Patent franchising tried to establish exclusivity, but they failed because of successful competition. For patent allies, several frustrated contracts kept the inventor's patent entries to protect "enthusiasts" and let them get patents. Whether the makers of the competition are really enthusiasts or not, these competitors have ignored it.

Commercial (USA) or government (USA) resident network

Federal radio commission

Federal Telecommunications and Transportation Commission

Born soap opera

Competing to use shortwave and FM

FM broadcast

FM radio was invented and patented by 1933. The use of FM is to minimize static electricity and interfere with the atmosphere of electrical equipment and audio-visual programs. W 1XOJ was the first experimental FM station, and 1937 obtained the construction permit issued by FCC.

Europe

In Europe, FM broadcasting was introduced after World War II. In 1948, a new wavelength plan has been set for the conference. Because of the recent war, it was not even invited. Germany (only gave a few media frequencies, which was not easy to broadcast). So Germany began to broadcast "ultrashort wave" (now called VHF) in USW. After some experience in using VHF, people realize that FM broadcasting is a better choice for VHF broadcasting than in the morning.

The development of the 20th century

Developed in the 20th century:

Sail on commercial morning radio. This situation lasted until the early 1960s, when the VOR system was finally popularized (the morning station was still marked with the American ... S. aviation chart).

In the early 1930s, the only sideband was invented by amateur operators. Ten years ago, they were established in a commercial way.

As early as AD1920s, radio was used to transmit images as visible as television. Standard analog transmission began in North America and Europe in the1940s.

1954, Regency introduced a pocket transmitter radio powered by "Standard 22", TR- 1. 5V battery. "

1960, Sony introduced their first transistor radio, which was small enough to be put in a vest pocket and powered by a small battery. It's durable, because no pipes are burnt out. In the next twenty years, except for very high power or very high frequency applications, transistors have been almost completely replaced.

1963 transmitted color TV service and launched a communication satellite TELSTAR.

In the late 1960s, the long-distance telephone network in the United States began to transform into a digital network, and many links used digital radio.

In the 1970s, it became the primary radio navigation system. Soon, the American team and navy experimented with satellite navigation, which reached its climax when they invented and launched the GPS constellation 1987.

In the early 1990s, amateur radio experimenters began to use personal computers to process radio signals through sound cards. In 1994, the US Army and DARPA started a bold and successful project to build a software radio, which can be changed into another radio by changing the software.

Digital transmission began in the late 1990s.

The teleprinter is on the radio.

The telecommunications law was not broadcast on the radio. On the contrary, the degree of automation has improved. In 1930s, the internal code of teletypewriter was adapted to the automatic transmission of pulse code dialing, and this service was called telex. In the past 30 years, telex is the cheapest way of long-distance communication, because 25 telex channels can occupy the same bandwidth as a voice channel. For the affairs and the government, this is the advantage that sending telegrams directly to users directly leads to written documents.

Teletypewriter system adapts to the unique sideband of short-wave broadcasting. 44 (the most advanced standard for pure teletypewriter) is a combined character-level missing code detection and broadcasting, as well as automatic internal coding and transmission.

For many years, telex was the only reliable way to contact some third world countries by radio. This outbreak is still reliable, although expensive e-mail forms offset it. Many national telecommunications companies have historically operated almost pure telex networks for their governments, and they have operated many contacts with short-wave radios.

2 1 century development

Internet radio includes an output connection that sends radio-style audio-visual programs: there is no need to include a radio transmitter at any point in the process.

Early technical war: push or pull, media outflow or multicast

Use live365 or software like Geocities or Hotmail to run your own site.

In several countries, digital audio-visual broadcasting (tapping) seems to be more and more important than FM broadcasting.

Digital audio-visual broadcasting

XM radio

Sirius satellite broadcasting

WLAN

World digital broadcasting station

Unusual technology

Flying stars dissipate

Moon bounce

Domestic network