High Integrity Position, Navigation, and Time (PNT) and Threat Localization within the Android Operating System

Android devices are some of the most widely used and prevalent pieces of technology to date with billions of daily users across the globe. Each of these devices is equipped with many sensors and connected to a range of different signals. Due to their prevalence and connectivity worldwide, Android devices provide a unique opportunity to monitor different types of security threats that are increasingly becoming more seen both on the battlefield and in civilian spaces. These threats include radio frequency interference (RFI) of GPS/GNSS, cellular, Wi-Fi, and Bluetooth signals as well as audible gunshots and visible unmanned aerial systems (UAS) such as drones.  Humla LLC is proposing to design and build a client/server software system to run on Android devices to create a network of devices to monitor, detect, and localize concerning RFI and other threats. The PI has reliably proven the ability to monitor, detect, and localize RFI on GNSS signals as well as provide a high integrity positioning, navigation, and timing (PNT) solution even in the presence of RFI. The Android platform offers many powerful GNSS integrity metrics, including automatic gain control (AGC) and carrier to noise ratio (C/N0), across all GNSS frequencies and constellations. Previous work has proven that AGC and C/N0 allow for the localization of an RFI emitter using power difference of arrival (PDOA) assuming a large number of phones distributed over an area. This effort will integrate these methods into a network capable of real time detection and localization.  The detection and localization methods used for GNSS RFI are applicable to many other frequencies and signals including cellular, Wi-Fi, and Bluetooth and this effort will apply these methods to these signals using their respective power metrics. Other localization methods, such as time difference of arrival (TDOA), will be used for signals with slower propagation speeds, such as audible gunshots recorded with the internal microphone. Other sensors built into Android phones such as inertial sensors and cameras allow localization of visible threats that only require the user to point the device in the direction of the threat.  This software system will particularly be of great value to warfighters, who will be able to use their Android devices as a quick all-in-one threat monitoring and localization tool, where quick localization means quick mitigation of a threat. Commercial entities and law enforcement can use the app to detect and localize threats such as GNSS RFI at airports or gunshots.