Military industrial hegemony

Chapter 1271 Information and Data Relay Multipurpose Experimental Communication Satellite
To be honest, it is quite controversial for private companies to own satellites, because there is no such precedent before.However, Jiang Chen's application now seems a bit abrupt to many people.But fortunately, Jiang Chen has made sufficient preparations in advance. He will explain why he submitted this application, what kind of satellite he will develop and manufacture, and what it will be used for.For this reason, Jiang Chen sent tens of thousands of relevant feasibility reports and related materials up and down, and such a report and related materials add up to more than 1000 pages.

It is precisely because of this report that everyone understands the significance of Jiang Chen's proposal to develop and manufacture such a satellite.The first is the information and data relay multi-purpose experimental communication satellite. Although we have launched many communication satellites before, this information and data relay multi-purpose experimental communication satellite is still different from the traditional communication satellites launched before. It's so different.First of all, the properties are different. Most of the previous communication satellites used analog signals for information transmission. This is similar to the relay station of a radio station, and it is still carried out in the form of signal encoding.As for this information and data relay multi-purpose experimental communication satellite, it uses digital communication technology, and all information is transmitted using digital encoding, whether it is in terms of accuracy, capacity, transmission rate, or security. , digital signals are not 01:30 points higher than traditional analog signals.More importantly, it has a wider service range. Compared with traditional communication satellites, which can only transmit one or two types of data information signals, the types of information and data that this information and data relay multi-purpose experimental communication satellite can transmit will be much more.This is a bit like the network switch of later generations, with very strong compatibility.

In fact, there are still many differences between the two. If you want to make it clear, it is more responsible.First of all, to clarify this problem, we must first know what is an analog signal and what is a digital signal.To put it simply, an analog signal refers to information represented by a continuously changing physical quantity, and the amplitude, frequency, or phase of the signal changes continuously over time.For example, the sound signal currently broadcast, or the TV image signal, etc.The digital signal means that the value of the amplitude is discrete, and the amplitude representation is limited to a limited number of values.Binary code is a kind of digital signal. The binary code is less affected by noise and is easy to be processed by digital circuits, so it has been widely used.

The data that is different from the analog signal and the digital signal must be converted into a corresponding signal before it can be transmitted. Analog data generally uses analog signals, such as electromagnetic waves in radio and television broadcasting, or audio voltage signals in telephone transmission, etc., which can be transmitted through analog data. Signal pulls for transmission.The digital data uses digital signals, such as using a series of intermittently changing voltage pulses to see the binary digital code, using a constant positive voltage to represent the binary number 1, and using a constant negative voltage to represent the binary number 0, thereby changing the corresponding digital information signal for transmission.

Analog communication has the advantage of being intuitive and easy to implement, but has two major drawbacks.Analog communication, especially microwave communication and wired open-wire communication, is easy to be eavesdropped and interfered.As long as the analog signal is received, the content of the communication can be easily obtained.During the transmission along the line, the electrical signal will be interfered by various noises from the outside world and from within the communication system. It is difficult to separate the noise and the signal after they are mixed, thus degrading the communication quality.The longer the communication distance, the more noise will accumulate.

The digital transmission and exchange are more superior, strengthening the confidentiality of communication.After the voice signal is converted by A/D, it can be encrypted first, and then transmitted. After being decrypted at the receiving end, it can be restored to an analog signal by D/A conversion, which improves the anti-interference ability.The digital signal will be mixed with noise during the transmission process, and the threshold voltage or threshold value formed by the electronic circuit can be used.To measure the input signal voltage, the circuit will have an output value only when it reaches a certain voltage range, and automatically generate a neat pulse, which can also be called shaping or regeneration.When a small noise voltage arrives, it is filtered out because it is lower than the threshold, and will not cause circuit action.Therefore, the regenerated signal is exactly the same as the original signal, unless the interference signal is larger than the original signal, a bit error will occur.In order to prevent bit errors, a method of checking and correcting errors is set in the circuit, that is, when a bit error occurs, the backward signal can be used to make the other party retransmit.

Therefore, digital transmission is suitable for long-distance transmission, and it can also be suitable for the harsh environment of signal transmission and reception.After adopting time-division switching, transmission and switching are unified to form an integrated digital communication network.Its transmission data capacity and efficiency, as well as its security are much stronger than the advantages of traditional analog data information transmission, which is also an important factor that countries in the world have been working on research on digital information transmission.Of course, with regard to digital information transmission, our country is not far behind, but regarding this relatively cutting-edge information and data relay multi-purpose communication satellite, it is only in theory and has not been put into practice.

There are many factors causing this situation, including technical reasons.After all, because of that special period, our country has stagnated in related technical fields for many years.So in this respect, there is a certain gap between us and the international advanced technology.And another part of the reason is the funding aspect. To put it bluntly, there is still no money.During this period, not only the army endured, but also other aspects, all of which had to be compromised for the sake of economic construction.To put it bluntly in the field of scientific research, especially in the field of cutting-edge technology that is relatively expensive, the funds used for exploration and research and development are pitifully small.

This period is not like the later generations. Many institutes of later generations cooperate with enterprises or other institutions in scientific research, so the sources of funds are relatively wide and sufficient.During this period, the sources of funds that these research institutes and related units relied on were still allocated by the state and higher-level projects.Under the current circumstances, the areas that the state can take care of are really limited, and we can only choose key points for support.Therefore, many projects have been forced to stall for this reason.

But now, Jiang Chen offered to provide funds, which makes these research institutes not excited.So as soon as the news came out, these related research units came one after another.In order to be able to compete for this project, these units have gone to great lengths. In addition to praising the funds, they are constantly running on other units, and even once got into a fight because of this matter.In the end, under the mediation of the above, the matter of z was resolved.

(End of this chapter)