Mobile Network Cottage Edition (OPENBTS) "2" band Story

Story of the "2" band

The OPENBTS system has two highlights. One is the wireless transceiver, especially the frequency band processing, the other is the network system, especially the alternative to the traditional base station (BTS), the base station controller (BSC), the Mobile Control Center (MSC), and (HLR/VLR) alternative solutions.

Say the frequency bands first, the story starts from 1894. This year, German physicist Heinrich Hertz died. The most important thing about Hertz's success in life is the discovery of electromagnetic waves. After the death of Hertz, no published notes were collated and published. This year, the 20-year-old Italian lad Guglielmo Marconi to the Alps for a holiday with a Hertz note in his luggage. In the silent and fresh air of the mountain, Marconi to read these notes with great concentration. Reading and reading, the inspiration came to mind that he might be able to use the method of transmitting and receiving electromagnetic waves to realize the transmission of information. The more I want to get excited, so he gave up on vacation, hurriedly down the hill, back to the lab for more than 10 days, the first wireless telegraph in the history of the advent of this.

Then go to venture capital, but look for Italy, no one cares. Helpless, two years later, Marconi decided to go to more spare money in Britain to take a chance. Sure enough, London was the land of Marconi transshipment, the invention of the radio newspaper, which was favored by the chief Engineer of the British Ministry of PTT. With strong funds to do backup, the development of the radio is smooth sailing. The launch radius of the radio station is from 6 km to 16 km, sharply expanding to 3000 km. Soon, the overseas telegraph was realized, and Marconi's career expanded to North America.

Figure 7. Marconi ' s antenna for Cross-ocean Telegraph, Poldhu, England, 1901. [1]
Http://farm5.static.flickr.com/4044/4264557223_14c6f664f6_o.jpg

Figure 7 is Marconi in 1901, in a rural poldhu in the southeastern corner of the country, to erect a telegraph antenna for the ocean. The Telegraph was very large and housed in a hut in the lower left corner of the picture. [1] When the Telegraph was running, it was able to hear a roar thousands of meters away, and the flickering, intermittent glare of the blue arc in the hut was seen at night.

Not only horrible, but also embarrassing. When Marconi's career expanded to the United States, he met a strong rival, American inventor Lee De Forest. De Forest is a university professor in Illinois, the three-pole tube is his invention, until 1948 years, William Shockley and other people invented the transistor, transistor gradually fade out of the historical stage. De Forest also has a radio reporting system. The embarrassing thing happened and the two systems could not be used at the same time. Helpless under, both sides had to negotiate, to five minutes for a paragraph, the two sides use in turn.

Why can't there be multiple radio reporting systems at the same time working at the same time? Because Marconi and De Forest's wireless telegraph works Similarly, they are all using a discharge (Spark Gap) to generate electromagnetic waves by controlling the rhythm of the discharge, allowing the electromagnetic wave to pass Morse code (Morse code), while Morse code carries information that needs to be transmitted. Spark gap mode generated by electromagnetic waves, occupy the entire electromagnetic spectrum, so a mountain not two tigers, the only possible way of cooperation is that we take turns Republicans.

This dilemma, finally in 1906, was a breakthrough by Canadian prodigy Reginald Fessenden. Fessenden, only 14 years old, has shown a prominent mathematical genius, was assigned to the school assignment mathematics, to other children class. Since then, he has been involved in radio research and, at the age of 40, invented the amplitude modulation carrier technology (Radio Carrier Wave), which is now familiar to everyone. The Fessenden approach, which has two advantages over Marconi and De Forest, is to break the Morse code limit, improve the efficiency of information transmission, and allow multiple radio stations to work simultaneously.

1. The so-called amplitude modulation is the transmission of information by adjusting the amplitude of the electromagnetic wave. If the amplitude is only two states, then the carrier transmits Morse code. If the amplitude is set to a variety of states, then the carrier transmission of information is far richer than Morse code.

2. When multiple radio stations are working simultaneously, each station occupies one frequency, thus avoiding mutual interference.

If Marconi open up the new field of wireless communications, then this field to mature, inseparable from the contribution of Reginald Fessenden. This invention is of great significance, it not only solves one or two technical problems, but also discovers a new idea. This idea is the carrier, not only amplitude modulation can be carrier, and adjust the frequency or adjust the phase can also be carrier. Therefore, the emergence of FM (Frequency modulation) technology is a logical follow-up development. [2] in 1933, FM technology patents were obtained by the American Edwin Armstrong.

While radio technology has soared, the world has gone through a war, and the threat of the war has grown stronger. The U.S. military believes that radio technology is dominated by British-backed Marconi companies, which are bad for U.S. national security. Under the control of the U.S. Navy, GE bought the assets of the Marconi US subsidiary and teamed up with other US companies, including at-T, Westinghouse and others, to set up the US radio Company (Radio Corporation of America), which monopolized the US radio business.

Figure 8. RCA chief David Sarnoff jumps for joy on Dec, 1953 upon being informed the FCC have approved the RCA/NBC color TV standa RD [4].
Courtesy Http://farm3.static.flickr.com/2510/4268366328_3606afd573_o.jpg

When it comes to RCA, David Sarnoff. Sarnoff was born in a poor Russian Jewish immigrant family, and was sold on the street to subsidize household use. At the age of 15, he was apprenticed to the Marconi American branch. Although there is no solid foundation for education, but with his diligence and the Sarnoff, the 13 years later as the company's business manager.

In 1919, GE purchased the Marconi US Branch and established RCA, and Snarnoff became an RCA employee. The following year, Sarnoff began to steer RCA, serving for half a century. Under his impetus, radio and television became emerging industries, and NBC and ABC grew into media oligarchs across the United States, while driving the prosperity of the entire industrial chain from communications equipment to personal consumer electronics. In 1970, the 79-year-old Sarnoff retired and handed the heyday of RCA to his son. But the son did not inherit his father's mantle. RCA from this declining, to linger for 1986 years, finally died.

There has been a business tycoon in all dynasties, but like David Sarnoff, it is not uncommon in human history to be able to discern the potential of a new industry, to anticipate the prospects of an emerging industry, and to be bold and quick to become stronger.

In 1906, Sarnoff into the Marconi American Branch Apprentice, ten years later, his understanding of the new technology of radio has been very thorough. At that time, scholars of the idea of the application of electromagnetic waves stay in the telegraph and telephone these point-and-out communications, and sarnoff a different, he believes that radio technology can be counter switch, applied in other areas. In 1916, he proposed the idea of a "music Box", the prototype of radio and radio. But because of the First World War, the idea of radio was not realized until 1921. This year, Sarnoff successfully organized a live broadcast of a boxing match, attracting 300,000 listeners. Once confirmed that the broadcasting market is promising, sarnoff in a desperate frenzy, in less than two years, to determine the RCA in the emerging broadcasting market dominance.

In 1926, Sarnoff the broadcasting business from RCA and set up NBC. Soon, NBC became the Big Mac of All-American media. In 1943, under anti-monopoly pressure, NBC was dismantled to two, becoming NBC and ABC two companies. After the end of World War II, television services also soared. NBC and ABC became two-Habitat giants for radio and television.

The boom in the broadcast and television industry, coupled with telegraph and other communications, has led to an increasingly congested radio band. In 1934, the United States established the Federal Communications Commission (Federal Communications Commission, FCC), responsible for coordinating the distribution of channels and so on.


Reference,

[1] The Marconi section of the broadcast archive. (http://www.oldradio.com/archives/jurassic/marconi.htm)
[2] The father of FM. (http://inventorspot.com/father_of_fm?page=0%2C2)
[3] RCA history. (Http://en.wikipedia.org/wiki/RCA)
[4] David Sarnoff ' s jumps for joy. (http://www.cedmagic.com/featured/war-worlds/sarnoff-jumps.html)

Mobile Network Cottage Edition (OPENBTS) "2" band Story