Spyglass: Directional Spectrum Sensing with Single-shot AoA Estimation and Virtual Arrays

TL;DR

Spyglass is a spectrum sensing system that accurately estimates the direction of signals using a single transmission and virtual arrays, enabling efficient spectrum management in dense wireless environments.

Contribution

It introduces a novel single-shot AoA estimation method with virtual arrays and a protocol-agnostic detection algorithm, reducing cost and complexity.

Findings

Median AoA accuracy of 1.4 degrees

Separates multiple simultaneous signals effectively

Operates with commercially available hardware

Abstract

In this paper, we introduce Spyglass, a spectrum sensor designed to address the challenges of effective spectrum usage in dense wireless environments. Spyglass is capable of observing a frequency band and accurately estimating the Angle of Arrival (AoA) of any signal during a single transmission. This includes additional signal context such as center frequency, bandwidth, and I/Q samples. We overcome challenges such as the clutter of fleeting transmissions in common bands, the high cost of array processing for AoA estimation, and the difficulty of detecting and estimating channels for unknown signals. Our first contribution is the development of Searchlite, a protocol-agnostic signal detection and separation algorithm. We use a switched array to reduce cost and processing complexity, and we develop SSFP, a signal processing technique using Fourier transforms that is synchronized to switching boundaries. Spyglass performs multi-channel blind AoA estimation synchronized with the array. Implemented using commercially available hardware, Spyglass demonstrates a median AoA accuracy of 1.4$^\circ$ and the ability to separate simultaneous signals from multiple devices in an unconstrained RF environment, providing valuable tools for large-scale RF data collection and analysis.