continues! The military exercises in the waters surrounding Taiwan that were originally planned to end on the 7th are still continuing. Next, they will focus on organizing joint anti-submarine and sea assault operations.
Seeing this exciting result, I feel both unexpected and reasonable. Now, our warship has naturally broken through the so-called central line of the strait. Unexpectedly, the United States came to provide an "assist".
A few days ago, Speaker of the U.S. House of Representatives Pelosi insisted on venturing to Taiwan despite strong opposition from my country. However, she stole the chicken but failed to lose the rice. It allowed us to take a big step towards national unity.
Those of you who are in front of the screen must also remember that at that time, the media said that more than 500,000 people were tracking their flight movements through the flight information platform FlightRadar24 at the same time, and the website was even paralyzed for a time. So how is real-time tracking of Pelosi’s flight achieved? What is the "help" behind the scenes?
Above: Image showing the tracking of Pelosi's flight to Taiwan
It turns out that real-time tracking of Pelosi's flight was accomplished through a system called Automatic Dependent Surveillance Broadcast, or ADS-B. ADS-B system includes ground station and airborne equipment. Common ADS-B ground equipment mainly includes data receiving and receiving, data processing, network transmission, information storage and other equipment and data application systems. In addition to the data application system, the rest of the ground equipment is mainly used for ADS-B data processing and transmission.
In addition, aircraft equipped with the ADS-B system airborne equipment can automatically (once per second) determine its position through satellite navigation or other sensors without manual operation or inquiry, and regularly broadcast it to the outside to make it can be tracked. The information can then be received by the air traffic control ground station as a replacement for the secondary radar .
So what is the difference between it and secondary radar transponder ? For example, a person holds a loudspeaker and constantly asks people around him for their location. When someone hears the call, they quickly respond: "I am at such and such a location." This is the usage scenario of the secondary radar transponder.
And if all the people walking on the street raise their horns and shout: "I am at such and such a position, what is my height and what is my speed." In this way, everyone can know each other's position and related information, this is ADS-B usage scenarios.
Moreover, the ADS-B system can automatically obtain parameters from relevant airborne equipment without manual operation or inquiry, and broadcast its own four-dimensional position information (that is, longitude, latitude, altitude, time) to other aircraft or ground stations and Additional information (conflict warning information, route turning point information, etc.) as well as aircraft identification information and category information are provided for controllers to monitor the status of the aircraft, thereby improving flight safety and efficiency.
However, once the plane turns off its "speaker" and no longer broadcasts its position to everyone, it enters a state of silence, which is why Pelosi disappears for several hours from time to time. But this small flaw does not affect the excellent performance of ADS-B.
First of all, the construction and use cost of ADS-B ground stations is one-ninth of that of traditional radar surveillance systems. Secondly, the data accuracy of ADS-B is high, which can be improved to the 10-meter level, and the monitoring data update speed is faster (twice per second). In addition, the information it transmits is richer and its service life is particularly long.
In view of the various advantages of ADS-B, the construction of ADS-B systems is actively promoted around the world. Currently, the earliest known mandatory requirement for ADS-B was in Canada's Hudson Bay in November 2010.
In addition, since most of the airspace in Western Australia is not covered by radar systems, they began to mandate ADS-B operations in December 2013 to avoid expensive radar system construction and maintenance costs.
Above: ADS-B data coverage distribution map
In addition, starting from January 1, 2020, the United States plans to make ADS-B Out equipment mandatory for all aircraft (similar to where transponders are currently required). And now more than 630 ground stations have been deployed.
However, in contrast, we still lack realistic and feasible planning arrangements in many aspects such as ADS-B practical technical research, airborne equipment equipment, ground system construction, and operational skills training for flight and controller personnel.
Above: ADS-B equipment site distribution map
However, it is worth noting that ADS-B also has limitations. The most critical point is that its positioning completely relies on the global satellite navigation system (ie GNSS).
After the aircraft receives the location information through GPS, the device itself does not have the ability to verify the correctness of the location. If the location information is incorrect, the ground station cannot identify it.
Moreover, because the ADS-B protocol is open and unencrypted, it also brings about very serious data security issues.
For example, using simple radio equipment, you can receive and analyze key operational information such as the aircraft's identity, position, speed, altitude, and heading.
Moreover, there are many companies at home and abroad that produce ADS-B ground receiving equipment, and they also sell large quantities of equipment to non-professional institutions and ordinary people at will.
For example, FlightRadar24, which has been used by hundreds of thousands of people to monitor Pelosi's flight movements, is an application based on ADS-B that provides real-time flight information to users around the world.
Generally speaking, although the ADS-B data that can be broadcast publicly is not confidential, if it falls into the hands of a deliberate eavesdropper with ulterior motives, the superposition of massive data will become a "weapon" that can hurt people, and it is very likely to cause harm to aviation. Operation brings unpredictable risks.
