Riding the wind of rebirth

Zhou Zhi is really not worried at all about the technical strength of China's aerospace industry and the conscientious and diligent attitude of its staff. Later experience has also proved that after China's military industry iterated its quality management system, the number of errors in space missions has been greatly reduced, and various achievements have been made with each passing day.

Later on, I wanted to have everything that existed in the world, and I also wanted everything that didn't exist in the world. In the end, I even went to the back of the moon to dig mud.

Perhaps he had misunderstood Zhou Zhi's expression, so Elder Yu gave everyone another reassurance: "What I can guarantee is that it will definitely be cheaper than the original plan for a single satellite... uh, a lot!"

"Then please, second brother, renegotiate on this basis?" Zhou Zhi tilted his head to seek Li Laoer's opinion.

Li Laoer put down his pen with a wry smile: "Then let's talk about it. If we can build a network, our subsequent contract with Yangtze Telecom may also need to be changed..."

This exchange was a surprise attack by Zhou Zhi on several veteran experts. Fortunately, the experts were well-informed and familiar with all kinds of data and techniques, so they were not affected at all.

However, no matter how brief the talk was, it was already noon and no one was interested in eating. After a simple meal in the cafeteria, everyone returned to the meeting room to continue the discussion.

This time the discussion is about the feasibility of the "satellite base station network".

"Is Xiao Zhou's idea inspired by the 'Iridium Project'?"

After being reminded, Zhou Zhi slapped his forehead and remembered that someone had already "taken the lead" in his plan.

In 1987, in response to the limitations of traditional terrestrial cellular telephone networks, Motorola proposed a global personal digital mobile communications system consisting of 77 low-orbit small satellites.

Once the system is connected to the existing telecommunications network, it can achieve seamless global coverage.

Since it uses 77 satellites to operate in 7 geocircular orbits, the distribution is similar to the distribution of electrons in the outer layer of iridium atoms, so it is called the "Iridium" system. Later, due to design modifications, the constellation structure was changed to 66 satellites operating in 6 geocircular orbits, and the system is still named "Iridium".

This was the once glorious "Iridium Project".

"I do know about this plan, but I feel that the project is a bit mysterious."

"Oh? You are not optimistic either?" Mr. Yu's eyes suddenly lit up: "Tell me, why are you not optimistic?" Zhou Zhi has the experience of later generations. He knows that this project has attracted hundreds of billions of dollars in global investment and has driven a series of projects in the entire aerospace industry chain from satellite manufacturing to rocket launches. Everyone is even cheering that the era of satellite stations replacing ground stations has arrived.

However, as expected by the elders, Iridium burned through $66 billion in just over a year after its launch, and then declared bankruptcy due to insufficient users and the termination of commercial services. Finally, in two years, 66 satellites entered the "derailment and self-immolation" process one after another, and the Iridium project came to an end. Of course, this cannot be said. Zhou Zhi thought for a while and said, "It is like this. The investment in this plan is too large, but even the basic application scenarios have not been thought out. Although global data transmission is still in a low-speed era, satellite communications should have the advantages of low latency, low cost, wide coverage, and broadband. However, the manufacturing and launch costs of satellites are difficult to achieve a balance between income and expenditure with only the current immature applications."

"At present, the development of satellite communications in the world is not mature, and the business model is not clear. If the application scope in extreme environments is too small, even if the Iridium plan can provide global communication services, this is impossible to achieve in the business model at that time." Zhou Zhi spread his hands: "Because the ground wired communication and wireless base station communication in the United States are too advanced."

"The biggest market should be the American government and military. If they don't approve of it, the application scenarios will be too narrow."

“Even if we get support from the U.S. government and military, it will still be difficult to expand the business model and develop suitable application scenarios.”

Although Zhou Zhi knew that this aspect could have many applications, he didn't need to tell Iridium. Wouldn't it be better to keep it to himself?

"Besides that, there are commercial ocean-going network applications and communications in remote areas." Zhou Zhi said with a smile, "Don't expect to make a profit if it's more about regional communications, unless the government gives enough subsidies. Commercial ocean-going services are more about phone calls and fax services, and network applications are too high-end. Such value-added services are of little use to ocean-going ships."

"Xiao Zhou is very capable of seeing so many problems in market applications." Old Yu nodded in agreement: "But we are in the technical field. From a technical perspective, the Iridium Project does have many weaknesses."

"For example, the frequency issue." An old man said: "The satellite frequency used by the Iridium Project is 317.5 MHz, but the satellite communication system of the International Satellite Organization ISG/ISE has a frequency range of 317.5 to 360 MHz."

"Therefore, the Iridium project needs to share the same frequency band with the current satellite communication system of the International Satellite Organization. However, the Federal Communications Commission of the United States does not allow frequency sharing between operators, so there is a legal disagreement on this issue, which has not been resolved."

"There are also problems with the design of Iridium," said another old man. "The channel capacity of Iridium is planned to be 40 Kb per second, while the capacity of satellite communication system stipulated by the International Satellite Organization is 100 Kb per second. In other words, the capacity of Iridium is far lower than the satellite communication capacity stipulated by the International Satellite Organization. If Iridium succeeds in networking, more satellites will have to use a capacity of 40 Kb per second in order to rely on its system, which will threaten the position of the International Satellite Organization and deprive it of its voice."

"Also, the Iridium project uses Ku-band satellites, and the Ku-band signal has a very low frequency, with a bandwidth of only kilohertz, while the current standard satellite communication system uses Ka-band signals, which have a high frequency and a bandwidth of up to MHz. This is a difference in magnitude."

Zhou Zhi understood immediately: "To put it simply, Iridium has the advantage of global coverage of one satellite. In terms of performance, it takes ten Iridium satellites to achieve the performance of one Dong-66 satellite. The communication capabilities of its satellites combined are actually equivalent to seven of our Dong-B satellites!"

“Haha, that’s not the way to put it.” Old Yu laughed and said, “This is not a simple matter of addition and subtraction. However, the high technical complexity, excessive investment, long R&D cycle, and weak system capabilities all exist.”

"The most critical question," said Li Laoer, an industry authority. "Can Iridium outperform the development of terrestrial mobile communication networks and optical communication networks? You know, the development of these two networks is also very rapid now."

This is also very important. If satellite networks are overtaken by terrestrial networks and fall far behind in performance, the development of satellite networks will lose its meaning. (End of this chapter)