What is the travel code? How does it work?

Since the epidemic, China has taken many prevention and control measures, including some black technology methods. Among them, the health code and travel code are used to use Big Data to assess and verify where a person has been and whether a viral infection is present, which can be used for better regional prevention and control.

?Since its introduction, the travel code has been accessed more than 25 billion times and has become an important tool in the fight against epidemics and for regional containment. When the cell phone is working normally, people can use travel codes to find out where they have been.

But have you ever thought about a question: how does the principle of "whole travel tracking" travel card work? Can I find it again after I remove the SIM card and turn off the phone?

Working principle of the travel code.

By delaying the healthy code, the real-time benefit of the travel code is now apparent. Since 2020, the three major telecom operators in China have been collecting signaling data based on hundreds of millions of cell phone users and base station locations. Cell phone users across the country can use the signaling data to show where they have been in the last 14 days.

The travel code, which we often refer to, is the Big Data travel map of communications. The travel code can accurately record the travel of the code holder, and its working principle is the analysis of the cell phone signal data by the base station.?

When the cell phone is functioning normally, any two cell phone users can establish a data channel. In doing so, the cell phone establishes the connection with the base station, which then forwards it to another user. The base station is only used for data transmission, but without it, the various communication terminals are useless.

When the information terminal transmits data, both the mobile terminal and the base station should follow the control instructions of the new system. These control instructions are different from the instructions we receive when talking on a cell phone. In this way, an information channel is temporarily established between the data terminal and the base station.

So the middle base station is an indispensable connection, whether we are making phone calls, sending messages or surfing the Internet. The cell phone must establish an information channel with the base station so that the base station can receive all the information data about the cell phone user. Only through these information channels and data can the BTS determine the specific location of the code holder.?

According to this principle, when your cell phone is turned on, the base station can receive signal data about the cell phone transmitter and receiver, even if the user has not performed any operation with the cell phone. If you stay in one place for more than 4 hours within 14 days, the data code will indicate that you have been in that area. Currently, this technology is accurate down to the city level.

The itinerary codes we normally use have a total of four colors. Only those with green codes can pass smoothly. The other three colors of the itinerary codes represent the possibility of COVID -19.

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Can the cell phone be tracked even in flight mode if the card is unplugged and turned off?

All cell phones and the base stations of the three major wireless carriers normally communicate with each other in the form of signal data. In this state, mobile phone users can be located.

?If the cellular card is in flight mode or there is no network, emergency contact can be made. There are a number of lines in the cell phone, all designed to allow the user to contact the base station as much as possible when there is no network. This means that the base station can find you even if you are not actively calling.?

Since the cell phone data of the three major operators are registered since we have the cell phone, the registration is maintained periodically. When the signal is lost, the registration is re-run, and the BTS also re-registers when needed. But in general, when the device is turned on, it sends signals regularly, usually every minute.

?The card SIM is associated with the phone number and the card SIM during network registration. If you know one of them in advance, you can use this connection to find other connected phones, SIM cards and phones in the future.

As far as public safety agencies are concerned, user tracking is done through the base station. Since the cell phone and the base station actively interact with each other, interaction with the base station can only be interrupted if the phone is turned off or physically shielded.

Now, under the conditions of the cell phone update iteration, is there really no connection between the switched-off cell phone and the base station?

?Currently, Android phones do not have a feature to turn off networks, but there are many tools and software that allow you to "convert" a phone to try to connect when it is turned off. Based on this principle of operation, the iPhone has already implemented this function with the IOS system. There are many such software on iPhone, which are powerful and expensive. Nevertheless, they are widely used by private detectives and others to track cell phones.

?Currently, OS15 has a function to find the cell phone even if it is turned off. The user can choose to disable the search when the phone is off. Since the user actively turns off the phone, this does not mean that the phone is completely off. While the aop processor continues to run, the user can enable the FindMy feature when the phone is turned off to allow the aop processor to control Bluetooth. The user's Bluetooth phone can be located with nearby Bluetooth facilities or NFC.

Although Apple's phone has achieved this function, customers who are more concerned about their privacy are worried about the current high-tech. Therefore, Apple claims that it can block the real data used by third parties to track customers. Of course, if it cooperates with three major operators, the travel code can be used normally in the future by using this functional principle.