CamFirm: A Compact FM-Based Module for Hidden Camera Detection

The rise of spy cameras has become a global concern regarding personal privacy. Unfortunately, affordable and easily accessible detection methods are lacking, leaving individuals vulnerable to these intrusive devices. Currently, most research focuses on detecting cameras based on their wireless transmission. Some of the latest research can detect other types of emissions from cameras but require costly equipment like universal software radio peripherals (USRP) or thermal cameras. However, this paper introduces a ubiquitous, cost-effective (less than $2) system, CamFirm, to identify and locate spy cameras regardless of their transmission mode. CamFirm only requires wired headphones and a Frequency Modulation (FM) module. Despite limitations of the FM module, such as narrow bandwidth, distortion, and vulnerability to interference, CamFirm remains capable of accurately identifying camera signals and pinpointing their locations. By utilizing the harmonics of digital circuits for signal screening, CamFirm can detect the photosensitive sensor signature of cameras and ascertain its direction through the attenuation of electromagnetic waves by the human body. The camera’s position can be further confirmed by activating a phone’s flashlight. Through extensive testing on 18 different cameras, CamFirm can achieve a median detection distance of 2.6 meters, effectively guiding users in locating the hidden camera.