Giant of the times

At 10 a.m. on January 10, the National Science Foundation (NSF) announced the establishment of the NSFNET network, which will connect six supercomputer centers in the United States through 56kb/s communication lines to achieve resource sharing.

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 handed Li Zetian a detailed information about NSFNET.

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

Dongfang Yuqin nodded: "Yes, Mr. Li, you are absolutely right!"

Li Zetian laughed and said: "Now that the National Science Foundation has started to take action, it is time for us to take action too!"

Dongfang Yuqin was not very clear about Li Zetian's plan, and looked a little confused: "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 build a metropolitan area network that connects ordinary people!!!"

After all, Dongfang Yuqin had been with Li Zetian for so long, and she was able to communicate with him at just one click. She was surprised and said: "Mr. Li, you mean, we buy local phone companies and borrow their phone lines to connect to the Internet?"

"Yes, that's right! As long as you have a modem, users can dial up the Internet."

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

A modem is a device that converts signals between a computer and a telephone line. It consists of a modulator and a demodulator. At the sending end, the modulator is a device that modulates the computer's digital signals (such as files, etc.) into analog signals that can be transmitted on the telephone line; at the receiving end, the demodulator converts the analog signals into digital signals 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 high. However, the construction cost of optical fiber lines is very high. In the 1980s and 1990s, telephone lines were basically used to access the Internet. Later, as the price of optical fiber increased, The reduction and the improvement of transmission speed have gradually become popular.

At present, Li Zetian will not sacrifice the basics and spend a lot of money to lay optical fiber. Instead, he will first seize the users and then update the hardware level.

This year was definitely very lucky for Li Zetian. The U.S. Department of Justice is preparing to split up AT\u0026T in accordance with the Antitrust Act, splitting it into a new AT\u0026T company that inherits the name of the parent company (specializing in long-distance phone business) and seven local phone companies (the "Bell Brothers"). The U.S. telecommunications industry will now enter an era of competition.

Before the split, AT\u0026T almost monopolized the intrastate, interstate and international telephone services in the United States and was a veritable super giant. Its turnover in 1983 exceeded the combined turnover of the other three large companies in the United States (Exxon, Mobil, and General Motors). These three major companies are all among the top 30 Fortune 500 companies. Needless to say, AT\u0026T is so impressive.

Now is a God-given opportunity for Li Zetian to enter the telecommunications industry! ! !

In fact, Li Zetian has never entered the telecommunications industry before, because he was waiting for the split of AT\u0026T. This antitrust lawsuit began in the early 1970s and lasted for more than 10 years. It was obvious that AT\u0026T was powerless.

At this time, Li Zetian ordered: "Dongfang Yuqin, pay close attention to AT\u0026T's antitrust case. As soon as there are results, notify me immediately!"

"Okay, Mr. Li."

Li Zetian thought for a while and stood up from his chair, "Go to Galaxy Network Company. I told Tian Shuai before that Galaxy Network Company wants to develop a modem. I wonder how the development is going now?"

Dongfang Yuqin nodded and immediately followed him.

…

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

Li Zetian said: "Do you know that the National Science Foundation (NSF) of the United States is establishing the NSFNET network?"

"Yeah, I got it!" The two nodded.

Li Zetian said: "As long as NSFNET is established, we can use modems to implement telephone line networking. How is the development of modems now?"

Tian Shuai said: "One quarter is done."

"So slow??" Li Zetian looked confused. Galaxy Network Company has a lot of talents and strong research and development efforts, so the development speed should be very fast.

Zhang Hao explained at this time: "Mr. Li, don't worry, there is a reason why the development progress is so slow. Currently, the fastest commercial modem is Bell212, which uses more stable shift keying technology to The rate is increased to 1200 bit/s."

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

"Oh, the term shift keying technology is a technology that uses two tones to represent 1 and 0..." Zhang Hao briefly introduced it, and then continued, "At first, when we were discussing, we also planned to use something like Bell Company's Bell212 system, but the product produced by this method is not much better than Bell212. Mr. Li, you must be dissatisfied, so we overturned the original plan and decided to develop a faster modem. After a period of research and discussion, we It was decided to adopt a new solution that can increase the data rate of the modem to 2400bit/s."

Li Zetian was shocked when he heard this and asked curiously: "What plan?!"

"The system is also similar to Bell212, but we use two-way signals on four pairs of dedicated lines to achieve 2400 bit/s."

It sounds a bit unclear!

However, Li Zetian understood. The two-way signal set naturally doubled the speed. Of course, it is easier said than done. It is no wonder that the development progress is a bit slow, which is understandable.

Li Zetian thought about it. It would take a long time for the National Science Foundation (NSF) to build the NSFNET network, and it would also take a while for him to acquire a local phone company. There would be enough time for Galaxy Networks to develop a modem.

"By the way, Galaxy Network Company cannot stop researching and developing optical fiber for a moment! The broadband of telephone lines is too small and the data transmission rate is too low, so it will definitely be replaced by optical fiber. I hope Galaxy Network Company can develop a low-priced fiber optic cable as soon as possible, but An optical fiber product with very powerful data transmission capabilities!" Li Zetian said.

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

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

Even if you look at a small optical fiber, it involves many cutting-edge technologies such as materials and optics, and its development is still very difficult.