At 10 a.m. on January 10, the National Science Foundation (NSF) announced the formation of an NSFNET network to connect six supercomputer centers in the United States through a 56kb/s communication line to achieve resource sharing. Pen & Fun & Pavilion www.biquge.info

When Li Zetian heard the news, his heart moved, and he immediately asked Dongfang Yuqin to collect more detailed information.

The next day, Dongfang Yuqin took a detailed copy of NSFNET and handed it to Li Zetian.

After reading the information, Li Zetian said: "NSFNET adopts a wide area network with a three-level hierarchical structure, and the entire network system consists of a backbone network, a regional network and a campus network. The host of each university can be connected to the campus network of the university, and the campus network can be connected to the nearest regional network, and each local network can be connected to the backbone network, which is then connected to the ARPANET through high-speed communication lines. In this way, any host in the school can access any supercomputer center through NSFNET and ARPANET, enabling information exchange between users!"

Dongfang Yuqin nodded: "Yes, Mr. Li, what you said is completely correct!"

Li Zetian laughed and said, "Since the National Science Foundation has started to act, it's time for us to take action!"

Dongfang Yuqin didn't know Li Zetian's plan very well, and showed a hint of doubt on her face: "Mr. Li, what are you going to do?"

"We don't have the right to build and operate the backbone network now, but ......," Li Zetian paused and said, "We can do a metropolitan area network that connects ordinary people!!

After all, Dongfang Yuqin had been with Li Zetian for so long, and she was surprised: "Mr. Li, you mean, we are buying local telephone companies and borrowing their phone lines to connect to the Internet?"

"Yes, exactly! With a modem, users can dial up the Internet. ”

Telephone lines can only transmit analog signals, while computers can only recognize digital signals.

A modem is a device for signal conversion between a computer and a telephone line, which consists of two parts: a modulator and a demodulator. At the sending end, the modulator is a device that modulates the digital signals (such as documents, etc.) of the computer into an analog signal that can be transmitted on the telephone line, and at the receiving end, the demodulator converts the analog signal into a digital signal that the computer can receive.

Data communication between computers can be achieved through modems and telephone lines.

Optical fiber does not need to rely on analog signals, but directly uses digital signals, so the speed and bandwidth are very large, but the construction cost of optical fiber lines is very high, in the eighties and nineties, basically the use of telephone lines to access the Internet, and then with the reduction of optical fiber prices and the increase of transmission speed, this is slowly popularized.

At present, Li Zetian will not give up the basics and spend a lot of money to lay optical fibers, but enclose the land to seize users first, and then update the hardware level.

This year is definitely very lucky for Li Zetian. The U.S. Department of Justice (DOJ) is preparing to spin off AT&T under the Antitrust Act, spinning it off into a new AT&T company that inherits the name of the parent company (specializing in long-distance telephone services) and seven local telephone companies (the "Bell Brothers"), and the U.S. telecommunications industry will enter an era of competition.

Prior to the split, AT&T had a near monopoly on intrastate, interstate, and international telephone services in the United States, making it a veritable super-giant company. Its turnover in 1983 exceeded that of the other three major companies in the United States (Exxon, Mobil, General Motors) combined. And these three companies are all top 30 companies in the top 500 companies, and there is no need to say how much AT&T hangs.

Now is a godsend for Li Zetian to enter the telecommunications industry!!

In fact, Li Zetian has not entered the telecommunications industry before, and is waiting for AT&T to break up. This antitrust lawsuit began in the early 70s and lasted for more than 10 years, and AT&T was clearly powerless.

At this time, Li Zetian instructed: "Dongfang Yuqin, pay close attention to AT&T's anti-monopoly case, and notify me as soon as there is a result!"

"Yes, Mr. Li. ”

Li Zetian thought for a while and stood up from his chair, "Go to the Galaxy Network Company, I told Tian Shuai before, the Galaxy Network Company wants to develop modems, I don't know how the current development is?"

Dongfang Yuqin nodded and immediately followed him.

……

More than an hour later, Li Zetian and Dongfang Yuqin rushed to the Galaxy Network Company, and then called Tian Shuai and Zhang Yan to the office.

Li Zetian said: "You know that the National Science Foundation (NSF) is going to set up an NSFNET network, right?"

"yes, got it!" the two nodded.

Li Zetian said: "As long as NSFNET is established, we can use modems to realize the function of networking with telephone lines. How's the modem being developed now?"

Tian Shuai said: "A quarter is completed. ”

"So slow??" Li Zetian looked puzzled, Galaxy Network Company is full of talents, research and development efforts are large, and the development speed should be very fast.

Zhang Yan explained at this time: "Mr. Li, don't worry, there is a reason why the development progress is so slow. Currently, the fastest commercially available modem is the Bell 212, which uses more stable shift keying technology to increase the data rate to 1200 bit/s. ”

"What is the shift keying technology?" asked Li Zetian.

"Oh, the shift keying technology is the ......technology of representing 1 and 0 with two tones," Zhang Yan briefly introduced, and then continued, "At first, when we were discussing, we also planned to use a system similar to Bell212 from Bell, but the product produced by this was not much stronger than Bell212. Mr. Li, you are not satisfied, so we overturned the original plan and decided to develop a faster modem. After a period of research and discussion, we decided on a new scheme that could increase the data rate of the modem to 2400bit/s. ”

Li Zetian was taken aback when he heard this, and couldn't help but ask curiously: "What plan?!"

"The system is similarly similar to the Bell 212, but we use a bidirectional signal set on 4 pairs of dedicated lines to achieve 2400 bit/s. ”

Sounds a little incomprehensible!

However, Li Zetian understands that the two-way signal set has naturally doubled the speed, of course, it is easy to say, but difficult to do, and it is understandable that the development progress is a little slow.

Li Zetian thought about it, it will take a long time for the National Science Foundation (NSF) to set up the NSFNET network, and it will take a while for him to acquire a local telephone company, so there is enough time for Galaxy Network to develop the modem.

By the way, Galaxy Network's research and development of optical fiber cannot be stopped for a moment! The bandwidth of telephone lines is too small, and the data transmission rate is too low, and it will definitely be replaced by optical fiber. I hope that Galaxy Network will soon be able to develop a low-cost, but very powerful optical fiber product with a very powerful data transmission capacity!" Li Zetian said.

Tian Shuai and Zhang Yan looked at each other and nodded.

"Don't worry, Mr. Li, Galaxy Network will definitely attach great importance to the development of optical fibers!" Tian Shuai assured.

Don't look at a small optical fiber, but it involves many cutting-edge technologies such as materials and optics, and it is still very difficult to develop.