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Main Authors: Chen, Wenhao, Zhang, Wenyi Morty, Sun, Wei, Bharadia, Dinesh, Ayyalasomayajula, Roshan
Format: Preprint
Published: 2026
Subjects:
Online Access:https://arxiv.org/abs/2602.00411
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author Chen, Wenhao
Zhang, Wenyi Morty
Sun, Wei
Bharadia, Dinesh
Ayyalasomayajula, Roshan
author_facet Chen, Wenhao
Zhang, Wenyi Morty
Sun, Wei
Bharadia, Dinesh
Ayyalasomayajula, Roshan
contents Hidden spy cameras have become a great privacy threat recently, as these low-cost, low-power, and small form-factor IoT devices can quietly monitor human activities in the indoor environment without generating any side-channel information. As such, it is difficult to detect and even more challenging to localize them in the rich-scattering indoor environment. To this end, this paper presents the design, implementation, and evaluation of SpyDir, a system that can accurately localize the hidden spy IoT devices by harnessing the electromagnetic emanations automatically and unintentionally emitted from them. Our system design mainly consists of a portable switching antenna array to sniff the spectrum-spread emanations, an emanation enhancement algorithm through non-coherent averaging that can de-correlate the correlated noise effect due to the square-wave emanation structure, and a multipath-resolving algorithm that can exploit the relative channels using a novel optimization-based sparse AoA derivation. Our real-world experimental evaluation across different indoor environments demonstrates an average AoA error of 6.30 deg, whereas the baseline algorithm yields 21.06 deg, achieving over a 3.3 times improvement in accuracy, and a mean localization error of 19.86cm over baseline algorithms of 206.79cm (MUSIC) and 294.75cm (SpotFi), achieving over a 10.41 times and 14.8 times improvement in accuracy.
format Preprint
id arxiv_https___arxiv_org_abs_2602_00411
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle SpyDir: Spy Device Localization Through Accurate Direction Finding
Chen, Wenhao
Zhang, Wenyi Morty
Sun, Wei
Bharadia, Dinesh
Ayyalasomayajula, Roshan
Cryptography and Security
Hidden spy cameras have become a great privacy threat recently, as these low-cost, low-power, and small form-factor IoT devices can quietly monitor human activities in the indoor environment without generating any side-channel information. As such, it is difficult to detect and even more challenging to localize them in the rich-scattering indoor environment. To this end, this paper presents the design, implementation, and evaluation of SpyDir, a system that can accurately localize the hidden spy IoT devices by harnessing the electromagnetic emanations automatically and unintentionally emitted from them. Our system design mainly consists of a portable switching antenna array to sniff the spectrum-spread emanations, an emanation enhancement algorithm through non-coherent averaging that can de-correlate the correlated noise effect due to the square-wave emanation structure, and a multipath-resolving algorithm that can exploit the relative channels using a novel optimization-based sparse AoA derivation. Our real-world experimental evaluation across different indoor environments demonstrates an average AoA error of 6.30 deg, whereas the baseline algorithm yields 21.06 deg, achieving over a 3.3 times improvement in accuracy, and a mean localization error of 19.86cm over baseline algorithms of 206.79cm (MUSIC) and 294.75cm (SpotFi), achieving over a 10.41 times and 14.8 times improvement in accuracy.
title SpyDir: Spy Device Localization Through Accurate Direction Finding
topic Cryptography and Security
url https://arxiv.org/abs/2602.00411