“Use on-board WiFi of Raspberry Pi to detect motion through walls via WiFi Radio Frequencies
Introduction
Ever wondered whether WiFi could be used for more than just communication? This project demonstrates that WiFi signals that can be absorbed and reflected by human body can be used for detection of motion using just Raspberry Pi’s on-board WiFi
CSI stands for Channel State information and is extracted from OFDM signals. We will be capturing 802.11 beacons because they are ubiquitous in 5GHz and easy to control on most routers. Note: On many routers still supporting 802.11b, 2.4GHz Beacons use DSSS instead of OFDM. OpenWRT based routers have the option to disable DSSS on 2.4GHz, while most OEM’s don’t offer such option. Moving forward, we will be working with 5Ghz band, specifically 36/80 or 157/80 channels, as supported by default patches.
NOTE: this procedure disables communication via on-board WiFi. Use Ethernet to access your Pi.
Setup
- Use official 32 bit raspbian image and update it to latest apt get update && apg-get dist-upgrade reboot.
- Enable CSI on Raspberry Pi by following this tutorial: seemoo-lab/nexmon_csi. If you encounter some challenges, you can also consult nexmonster where additional helpful setup scripts can be found. (Note: As of 20 Dec 2021, nexmonster was not updated for Raspberry Pi Kernel 5.10, which is supported by the official nexmon_csi project).
- Build makecsiparams and copy the resulting binary somewhere on your $PATH for ease of use.”