Beware of walls! Can Wi-Fi become a paparazzi and also a holographic image?

In the wilderness, two nimble figures move left and right. The one running in front is a fleeing wild deer, and behind it is a hungry cheetah. The wild deer cannot decide whether to become a delicious dinner or escape, just because it is not hidden well enough, it will become a meal. Privacy is very important, at least in the wild nature. Sometimes there is only one chance to survive, and there is no regret. Once the whereabouts are exposed, everything will be lost.

From the most primitive perspective, hiding is an instinct to avoid predators, and people's interest in seeing through camouflage and defense has never diminished. Perhaps driven by the instinct hidden in the blood, perspective ability always ranks at the top of the list of super powers that people want to have. Some time ago, the editor found that the Technical University of Munich published a paper in which their researchers developed a technology that uses Wi-Fi signals to generate a three-dimensional hologram of the surrounding environment.

Holographic projection

This means that the Wi-Fi at home may become a more secretive peeping device, and it is even better than the hacker's camera peeping. After all, Wi-Fi holography means a 360-degree God's perspective without blind spots. Once upon a time, Facebook founder Zuckerberg used the "homemade method" of physical isolation to prevent hacker intrusion.

In order to prevent hackers from invading, Zuckerberg put "shame" tape on the camera and microphone

However, once Wi-Fi holography is realized

Every minute you can experience the simple philosophy of "there are mountains beyond mountains, buildings beyond buildings, and there is always someone stronger than you"

According to the editor, the exploration of using Wi-Fi signals for similar "positioning" has never stopped. As early as a few years ago, there was a similar technology. In 2013, researchers at the Massachusetts Institute of Technology developed a technology that uses Wi-Fi signals to observe people's movements through walls. Not only that, this technology can also create a "contour fingerprint" for each person, breaking through the technical difficulty of distinguishing specific people through walls.

The so-called contour fingerprint is equivalent to giving a person an ID card based on perspective differences. Everyone's contour fingerprint is slightly different.

The team used a device called RF Capture to send wireless signals. When the wireless radiation passes through the wall and encounters the human body, the signal will be reflected back. At this time, RF Capture will analyze the received information and draw different contour fingerprints, which is very similar to the principle of radar and sonar imaging. According to the team, the amount of radiation emitted is very small, about one-tenth of the radiation of a mobile phone.

However, the research from the Technical University of Munich has taken this research a step further. What is the effect of using Wi-Fi signals to generate holograms?

Hologram of the cross

Using Wi-Fi holography to create a hologram of a warehouse

Inspiration may sometimes be just the product of thinking about a problem from a different perspective. Friedemann Reinhard, a researcher at the Technical University of Munich, said that this idea came to him during lunch. He just wanted to know what the world would look like from the perspective of Wi-Fi signals. So Wi-Fi holography was born. After all, sometimes the most silent thing is not the spring rain, but the Wi-Fi signal.

In an age where not having Wi-Fi can make people feel uneasy at best and mentally ill at worst, Wi-Fi's "penetration" ability is much more reliable than spring rain. The Wi-Fi signal emitted by the router can be used to generate a hologram of the surrounding environment.

“This technology is like seeing the world from a Wi-Fi perspective”

Friedemann Reinhard said.

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Giraffe Youqi, who has long seen the truth, has something to say

To perform a holographic scan, you need two antennas and an oscilloscope. One of the two antennas is fixed in one place as a reference, and the other is a movable scanning antenna, both of which are connected to the oscilloscope. In fact, the Wi-Fi hologram system captures the distortion that occurs when microwaves reflect off an object. By tracking this distortion information, physicists move the scanning antenna point by point and draw a hologram by comparing the readings of the two Wi-Fi receivers when the fixed antenna and the scanning antenna move on the virtual screen. In principle, the hologram encodes the image of any object in the room.

However, it must be mentioned that the technology is still in its infancy, and it is not realistic to expect to use it to monitor the entire building. Even if it can be done in theory, the cost is too high. There are two problems:

1. Monitoring an object as large as a building requires a mobile antenna that matches its size. (Movable antenna like a skyscraper)
2. The reason why surveillance is called surveillance is its concealment. It is almost impossible to install such a huge antenna quietly. After all, such a large rod-shaped object sticking around the monitored target is likely to become a shame in the surveillance industry.

However, researcher Philipp Holl added: There is a way to optimize the mobile antenna problem. Once the method is found, Wi-Fi holograms will have higher resolution. To put it bluntly, once the technical barriers of mobile antennas are solved, holograms will be clearer and more powerful.

This Wi-Fi holographic technology may have a wide range of applications in the future, including embedding microwave image data into camera images to easily track lost items. Imagine small objects such as keys that are easy to forget. In a Wi-Fi environment, you only need to take a photo of your home and you will see the lost object lying quietly under the bed.

In the future, this technology can be integrated with smart homes, allowing users to operate lights and TVs through gestures, or use this technology to adjust heating by monitoring the user's position in the room. Even given the ability of Wi-Fi signals to penetrate walls, in disaster-like first aid such as earthquakes, it can be used to find survivors under collapsed buildings... As far as the editor of Leifeng.com's Home Channel (letshome) personally guesses, in the future, Wi-Fi may be used more for positioning.

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In this increasingly transparent world, it is too difficult to defend privacy. The increasing maturity of Wi-Fi holographic technology may inevitably make people feel that their privacy is difficult to protect. But the truth is not absolute. Human progress stems from curiosity and exploration. We are like travelers walking in the desert to explore the unknown. There are shadows under the sun, and the shadows come from people, not the sun.

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