Talking about electromagnetic interference, we should first talk about electromagnetic and electromagnetic applications, then what is electromagnetic in the end? It is both invisible and intangible things, we are in the application of electromagnetism at every moment, large to the universe space, small to the microscopic particles are inseparable from the electromagnetic. In fact, people in many places in life are using electromagnetic. For example, heating food to the microwave oven, is the use of electromagnetic fields to make the food molecules constantly moving, and then the electromagnetic energy into heat, and ultimately heating food.
Again, for example, we need to use cell phone communication every day, which is the use of electromagnetic fields and electromagnetic waves can be transmitted through the principle of information, through the cell phone antenna will produce electromagnetic waves sent out, electromagnetic waves are received by the surrounding base station and then forwarded, and finally be received by the cell phone that we want to contact people, so that we have realized the wireless communication between people. Electromagnetic applications are very wide, many major projects are closely related to electromagnetic phenomena. For example, China's famous eye in the sky FAST, which is currently the world's largest caliber, the strongest single-caliber radio telescope. Simply put, the eye in the sky is an astronomical observation activity by converging electromagnetic waves in the universe, which is one of the means to explore the mysteries of the universe.
Human exploration of electromagnetic phenomena has never stopped. China is one of the earliest countries to recognize the phenomenon of magnetism, the ancient interpretation of magnetism was first recorded in the "tube": on the Ci Shi Shi, which is under the copper and gold. Ancient people have long applied magnets to medical treatment, pathfinding and other aspects of the use of magnets pointing invented the compass. The Ming Dynasty Zheng He went to the West is the use of the compass, to achieve the feat of ocean navigation.
With the development of electromagnetic continuously ushered in new breakthroughs, today, our relationship with electromagnetism has long been from the understanding, mastery of the development of the use of all the electrically charged equipment around us, have a close relationship with the electromagnetic. In the electromagnetic environment, electromagnetic interference phenomenon can be seen at any time. Electromagnetic interference can be divided into natural and man-made two categories. Natural electromagnetic interference is inherent in nature and human activities have nothing to do with electromagnetic interference, man-made electromagnetic interference is due to human industrial and social activities produced by electromagnetic interference.
Lightning is the most natural electromagnetic interference we usually see. For example, a civil aviation airliner was forced to land due to equipment failure, which eventually caused serious consequences of many casualties. Scientists investigated and found that the accident was because the airliner was struck by lightning during flight, during which the induced current and the induced electromagnetic field produced led to the failure of the aircraft. It is based on these painful lessons, China's independent research and development of large aircraft, seriously and systematically strengthen the protection of natural electromagnetic interference, which makes China's large aircraft has a very high reliability and electromagnetic safety. Strong electromagnetic phenomena also often occur in the solar system, such as sunspot eruptions, flares and so on, all of which produce serious electromagnetic interference. Severe sunspot eruptions can cause a total paralysis of the electrical power system, resulting in the disruption of wireless communications on Earth, and large fluctuations in the Earth's magnetic field for a variety of reasons. Such fluctuations could trigger electromagnetic interference in power and communication systems.
Next we come to man-made electromagnetic interference. For example, a light and shadow extravaganza of a thousand drones was staged in a certain place. Two days before the show, the rehearsal process of the drone formation was very smooth and the scene was majestic. But during the official performance there was an accident, nearly half of the drones were dazed, and the final image became garbled. The culprit was electromagnetic interference. Specifically, electromagnetic signals disrupted the drones' positioning systems, which led to major errors in the drone formation show.
There was also a case where a spaceship was threatened by electromagnetic interference before launch. At that time, the launch base center detected electromagnetic interference. In the launch site electromagnetic compatibility is a ringing project, must be foolproof, once the emergence of an unknown source of sudden electromagnetic interference, the technicians will have to carry out fine troubleshooting. Because once the rocket measurement and control commands are interfered with, it is very likely to lead to abnormal command reception, thus posing a threat to the safety of the spacecraft. In the end, after the staff's efforts to find the source of electromagnetic interference, ruled out electromagnetic interference, to ensure that the launch of the spaceship foolproof.
All circuits are susceptible to electromagnetic interference, some of which is received directly as radiation, and some of which is received through conduction. For example, reset, interrupt and control signals in our digital circuits are susceptible to EMI. Amplifiers in control circuits, as well as power supply adjustment circuits, are also susceptible to interference.
Let's talk briefly about electromagnetic safety. A number of incidents concerning malfunctions in smart grid-connected vehicles have caused extreme concern. Regarding this aspect of the problem, we have long put forward a research program, the experiment we found that when the vehicle encounters electromagnetic interference, it is likely to produce brake failure, can not stop the critical situation. Why it cannot stop is because our experimenters, by adding a transient electromagnetic interference next to it, triggered the electric vehicle system to produce a malfunction. In fact, the vehicle control system is equivalent to the brain of the car, all the information flow and data flow are exchanged through it, the brain is disturbed and failure, the whole car operation will be chaotic.
Similarly, autonomous driving generally relies on cameras and radar in the car to sense the surrounding environment. Through these sensors, the autonomous driving system recognizes status information such as the distance and speed between the car and the vehicle in front of it, and estimates the danger of collision. Once these sensors are subjected to strong electromagnetic interference, the vehicle's ranging sensors will be biased, thus greatly increasing the risk of rear-end collisions. Electromagnetic safety issues cause us concern, is because it often occurs in a moment, if you do not do a good job of pre-emptive, out of the problem when it is difficult to early warning, it is likely to cause a wide range of impact in an instant.
Lastly, let me briefly introduce the electromagnetic field and wireless technology program. China's electromagnetic field and wireless technology major, was formally established by the Ministry of Education, and included in the "general higher education undergraduate professional catalog". It is one of the urgently needed majors for the strategic construction of the country, and the world's strongest countries have set up medium- and long-term development plans around the electromagnetic spectrum, electromagnetic environmental effects, and electromagnetic safety and other fields, constantly highlighting the dominant position in the electromagnetic field, and listing it as one of the core technologies for national competitiveness.
Whenever equipment development encounters major challenges, the defense electromagnetic field often rushes forward to solve the country's most urgent problems. Where the country's most important and fundamental research is concerned, no one can tell you where the answers are. Therefore, I always tell my students that the development of the national defense science and technology industry relies on our own hard work and research, and this is the mission of our electromagnetic people. It is because of this challenge and importance that this specialty also brings us a great sense of achievement and honor.