Your Smartphone's GPS Can Secretly Track Your Activities and Environment, IIT Delhi Study Reveals

The research findings were published in ACM Transactions on Sensor Networks.

New Delhi:

GPS technology does more than just navigate or track deliveries. According to research conducted by IIT-Delhi, the "fine-grained" data collected by GPS on Android smartphones can silently reveal a person's activities, surroundings, and even the layout of their current room, going far beyond simple location tracking.

The study, "AndroCon: An Android Phone-based Sensor for Ambient, Human Activity and Layout Sensing using Fine-Grained GPS Information," was published in ACM Transactions on Sensor Networks, a leading journal focusing on privacy-aware sensing technologies.

Researchers introduced AndroCon, the first system demonstrating that "fine-grained" GPS data—already accessible to Android applications with precise location permissions—functions as an undetected sensor.

Without accessing the camera, microphone, or motion sensors, AndroCon analyzes nine low-level GPS parameters including Doppler shift, signal power, and multipath interference. This allows it to determine if someone is sitting, standing, lying down, riding the metro, flying, in a park, or in crowded outdoor spaces.

The system can even detect if a room is occupied or empty. To transform this complex raw data into clear insights, the researchers combined traditional signal processing techniques with advanced machine learning.

"Through our year-long study covering 40,000 sq km and various smartphone models, AndroCon achieved up to 99 percent accuracy in environment detection and over 87 percent accuracy in identifying human activities, including subtle movements like hand-waving near the device," explained Smruti R Sarangi, Professor in the Computer Science and Engineering Department at IIT Delhi.

The framework can also create indoor floor maps—identifying rooms, staircases, and elevators—with an error margin under 4 meters, using only GPS patterns and user movement trajectories.

While AndroCon presents exciting possibilities for context-aware, privacy-respecting smart services, it also exposes a significant security vulnerability. Any Android application with precise location permissions could potentially gather sensitive contextual information without users explicitly consenting.

"Our research uncovers a hidden dimension of GPS—a powerful but silent channel that perceives the world around us. AndroCon transforms ordinary smartphones into unexpectedly precise scientific instruments and reminds us that even familiar technologies harbor hidden capabilities that malicious entities could exploit," Sarangi concluded.