Everyone is looking for the latest gadgets and most advanced technologies, but sometimes the biggest wonders are hidden in places we pass by every day without noticing.

Imagine if your Wi-Fi modem had a strange capability: seeing through walls. This is not a joke or science fiction but a technological reality called "WiFi Sensing."

In this article, we will show you exactly how your ordinary internet signals can detect the presence and movement of people in the next room. If you are interested in discovering this amazing technology and the projects that have made it accessible to everyone, don't miss this article.

Yes, seeing through walls with Wi-Fi is entirely possible. This is done by analyzing precise information called "Channel State Information" (CSI). Projects like ESPARGOS use inexpensive hardware like the ESP32 to make this advanced technology accessible to everyone, allowing the use of Wi-Fi signal changes to identify objects.

What is Wi-Fi Sensing? A Simple Look at Complex Concepts

Imagine throwing a stone into a calm pond. Waves spread across the water's surface. Now, if an obstacle (like a piece of wood) gets in the way of these waves, their pattern changes. Wi-Fi sensing works on exactly this principle.

Your router constantly transmits Wi-Fi signals into the environment. These signals hit walls, objects, and people and are reflected back. Your phone or laptop receives these returning signals. When a person moves in the room, like that piece of wood in the pond, they change the pattern of the returning Wi-Fi waves. WiFi sensing technology analyzes these subtle changes and uses them to detect presence, movement, and even the number of people in an environment.

CSI: The Magic Key to Seeing the Invisible

Think of the Wi-Fi signal as having an invisible "heartbeat" in our surrounding environment. The simple signal strength indicator only tells us how "strong" this heartbeat is (e.g., 70 beats per minute). But this information is not enough.

CSI data acts like an advanced electrocardiogram machine for these same waves. Instead of a single number, CSI gives us a complete "graph" of the details of this heartbeat:

• The exact shape of the wave (amplitude and phase)
• Its rhythm and repetition pattern

Now imagine someone walking in the room or waving their hand. These movements, like an external factor, leave a unique and recognizable pattern (a "fingerprint") on this Wi-Fi ECG.

Therefore, CSI doesn't just tell us that something has changed; by analyzing the shape of these changes, it allows us to understand what kind of movement that thing likely performed. This is the key to seeing the invisible.

A Brief Introduction to the ESPARGOS Project

Until just a few years ago, accessing and working with CSI data required expensive, specialized equipment. But the ESPARGOS project has completely changed this equation. It is an open-source project that uses a few inexpensive ESP32 boards to create a powerful antenna array for collecting and analyzing CSI data.

Key Features of ESPARGOS:

• Inexpensive and Accessible: Built on the popular ESP32 microcontroller.
• Open-Source: All its hardware designs and code are freely available.
• Powerful: Provides the capability to collect high-rate CSI data, which is essential for precise analysis.

This project enables researchers, students, and enthusiasts to build their own Wi-Fi sensing system at a very low cost. For more precise technical information and access to the project code, be sure to visit the official ESPARGOS project website.

From the Lab to the Battlefield: Real-World Applications

This technology might seem like science fiction, but its applications are very real and expanding. From smart homes that turn on lights by detecting your presence to security systems that detect unauthorized entry without the need for cameras.

At more professional levels, companies like Camero-Tech with products such as the Xaver 1000 have brought this technology to military and rescue operation levels. These devices allow rescue teams to find living people under rubble or help special forces learn the number of people in a building before entering.

To better understand how it works and how to extract CSI data with tools like ESPARGOS, watching this technical presentation on YouTube that demonstrates the project details will be very useful.

A Look to the Future and Ethical Considerations

Wi-Fi sensing technology has the potential to change our lives, from elderly care (fall detection) to optimizing energy consumption in buildings. This field is so hot and popular that numerous scientific papers in reputable databases like IEEE Xplore have examined its various aspects. However, like any other powerful technology, privacy issues must also be seriously considered. Striking a balance between innovation and privacy protection will be the biggest challenge facing this technology.

Frequently Asked Questions (FAQ)

1. Does Wi-Fi sensing violate privacy?

This is a valid concern. Raw CSI data does not identify individuals; it only shows presence, movement, or breathing patterns. However, the use of this technology must be accompanied by transparency and adherence to privacy laws, especially in non-personal environments.

2. How accurate is detection with Wi-Fi?

Accuracy depends on various factors: the number of antennas, the power of processing algorithms, and the complexity of the environment. These systems cannot see people's faces, but they have shown surprising accuracy in detecting presence, number of people, speed of movement, and even some simple gestures.

3. What do I need to start working with ESPARGOS?

To get started, you need a few ESP32 boards, suitable antennas, and basic knowledge of electronics and programming. The ESPARGOS project website and its GitHub repository are the best starting points for accessing the necessary guides and codes.