Zhou Zhishi was really not worried about the technical strength of China's aerospace military industry and the serious and diligent attitude of its staff. Later experience has also proved that after China's military industry iterated the quality management system, the errors in aerospace missions have been greatly reduced, and various achievements have changed with each passing day.
Later, I had to have what I had in the world, and I had to have what I didn't have in the world. In the end, they all ran to the back of the moon to dig the dredge.
Maybe because he misunderstood Zhou Zhi's expression, Mr. Yu gave everyone a reassurance: "What I can guarantee is that it must be cheaper than the original single-star cost...well, quite a lot!"
"Then please trouble me, let me talk again on this basis?" Zhou Zhi twisted his head and sought Li Laoer's opinion.
Li Laoer smiled bitterly and put down the pen of the record: "Then let's talk about it again. If we can form a network, our subsequent contract of Changjiang Telecom may also need to be changed..."
During this exchange, several old experts were suddenly attacked by Zhou Zhi. Fortunately, the experts were all confident and the various data and techniques were well-versed and were not affected at all.
But even if it is concise and it is already noon when it is talked, noon is there any interest in eating. I simply dealt with it in the cafeteria and everyone went back to the conference room to continue discussing.
This time we are discussing the feasibility of "satellite base station network". "Is Xiao Zhou's idea inspired by the 'Iridium Plan'?"
After the reminder, Zhou Zhizhao slapped his forehead and remembered that someone had already "taken the lead" in his plan.
In 1987, Motorola proposed a personal digital mobile communication system covering the world with 77 low-orbit small satellites in response to the limitations of traditional ground cellular telephone networks.
When the system is connected to the existing telecommunications network, it can achieve seamless global coverage.
Because it uses 77 satellites to operate in 7 circular orbits, the distribution is similar to the electron distribution of the outer layer of iridium atoms, it is called the "Iridium" system. Later, due to the design modification, the constellation structure was transformed into 66 satellites operating in 6 earth-circular orbits, and the system was still named after the "Iridium" system.
This is the once extremely brilliant "Iridium Project".
"I do know this plan, but I feel that the project is a bit mysterious."
"Oh? Are you not optimistic either?" Old Yu's eyes lit up: "Tell me, why are you not optimistic?" Zhou Zhi has experience in later generations. He knew that this project attracted tens of billions of dollars of global investment, driving a series of entire aerospace industry chain projects from satellite manufacturing to rocket launches. Even everyone is cheering that the era of satellite stations replacing ground stations has arrived.
However, as several old men expected, Iridium burned $5 billion in just over a year after it went public, and then declared bankruptcy due to insufficient users and unable to make ends meet. The business services were terminated. Finally, in two years, 66 satellites entered the "deorbital self-immolation" program one by one, and the Iridium plan ended in a sad way. Of course, I can't say that. Zhou Zhi thought about it and said: "That's right. The investment in this plan is too large, but he has not even thought of the basic application scenarios. Although in the era of global data transmission in a low speed, satellite communications should have the advantages of low latency, low cost, wide coverage, and broadband, the manufacturing and launch costs of 66 satellites are difficult to achieve balance of revenue and expenditure based on the current immature applications."
"The current development of satellite communications around the world is developing globally."
" It has not yet matured and the business model is not clear. If the application range in the extreme environment is too small, even the Iridium project can provide global communication services, which is impossible in the business model at that time. "Zhou Zhi spread his hands: "Because the US's ground wired communication and wireless base station communication are too developed."
"The biggest market should be in the US's government and military. If they do not agree, the application scenario will be too narrow."
"Even if you have obtained support from the US government and the military, it is a difficult problem to expand your business model and develop suitable application scenarios."
Although Zhou Zhi knew that there could actually be many applications in this area, he didn't need to tell Iridium, how good it would be to keep it for yourself?
"Apart from this, it is business ocean network applications and remote regional communications." Zhou Zhixiao said: "If you prefer regional communications, don't expect to make a profit unless the government provides enough subsidies. Business ocean is more of a call and fax business, and network applications are too high-end. Such value-added services are of no use for ocean ships."
"Xiao Zhou can see so many problems from the perspective of market applications, which is very harmful." Yu Lao nodded and agreed: "But we are technical. From a technical perspective, the Iridium project does have many weaknesses."
"For example, the frequency problem." An old man said: "The satellite frequency used by the Iridium project is 317.5MHz, but the satellite communication system of the International Satellite Organization ISG/ISE has a frequency range of 317.5 to 360MHz."
"The Iridium program needs to share the same frequency band with the current ISAT satellite communication system. However, the Federal Communications Commission of the United States does not allow frequency sharing between operators, so there are legal differences on this issue and have not been resolved."
"Iridium's design also has problems." Another old man said: "The channel capacity of the ISAT program is 40Kb per second, while the satellite communication system stipulated by the International SAT organization is 100Kb per second, which means that the capacity of ISAT is much lower than the satellite communication capacity specified by the International SAT organization. If ISAT is With the successful networking, more satellites will have to use a capacity of 40Kb per second in order to rely on their systems in the future, which is equivalent to threatening the status of the International Satellite Organization and depriving it of its voice. "
"It is also true that Iridium plans to use Ku-band satellites, and the Ku-band signal has a frequency too low and its bandwidth is only kilohertz. Currently, the standard satellite communication system uses Ka-band signals with high frequency and bandwidth up to MHz. This is a difference in magnitude."
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Zhou Zhi immediately understood: "To put it bluntly, Iridium occupies more than one star, and the advantage of global coverage. Speaking of performance, only ten Iridium can achieve the performance of one East Three. The combined communication capabilities of its 66 stars are actually equivalent to our seven East Three B!"
"Haha, you can't say that." Old Yu smiled and said, "This is not a simple issue of addition and subtraction, but these problems exist in high technical complexity, excessive investment, long R&D cycle, and weak system capabilities."
"The most critical issue." As an industry authority, Li Laoer also spoke: "Can Iridium outperform the development of ground mobile communication networks and optical communication networks? You must know that these two developments are also very rapid now."
This is also very important. Satellite networks are overtaken by ground networks and have too many performances, and satellite networks lose their significance. (This chapter ends)