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

2026-03-11

AI Summary

This work addresses the challenges of low spectral efficiency, transient signal interference, and high computational cost in estimating unknown signals’ angles of arrival (AoA) in dense wireless environments. The authors propose a single-snapshot sensing architecture based on switched antenna arrays, integrating a protocol-agnostic blind signal detection and separation algorithm (Searchlite) with a Fourier transform–based SSFP signal processing technique. This approach jointly estimates multiple signals’ AoA, center frequency, bandwidth, and I/Q samples in a single snapshot. By significantly reducing both hardware requirements and computational complexity, the method achieves a median AoA estimation accuracy of 1.4 degrees on commercial platforms, enabling effective separation of concurrent transmissions and large-scale data collection in unconstrained RF environments.

Technology Category

• Search and Optimization: Mixed Discrete/Continuous Search
• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems
• Intelligent Robots: State Estimation

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Experiences and lessons learnt from Web-based algorithms and system deployments
• Security and Privacy: Large-scale security measurements
• Search and Retrieval-Augmented AI: Efficiency and scalability of Web search engines

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.

Problem

• spectrum sensing
• Angle of Arrival (AoA)
• dense wireless environments
• signal detection
• unknown signals

Innovation

• Angle of Arrival (AoA) estimation
• switched array
• blind signal separation
• spectrum sensing
• Fourier-based signal processing