Extraction of Audio Information from EM Emission Caused by Loose Connectors

When an electronic device is positioned near a speaker, speech information can be captured in unintentional electromagnetic (EM) emissions radiating from the device. This enables for the non-invasive retrieval of speech information from several meters without line-of-sight. Especially in this study, we explore a fundamental investigation into the feasibility of extracting audio information from EM emanations associated with “connectors with loosening.” This is because a loose connector has an “unstable physical structure” at its internal contact boundary and is susceptible to vibrations induced by the sound from the speaker. Specifically, we aim to restore audio information by measuring the common-mode currents generated by “connectors with loosening” positioned near the speaker. Our experiments demonstrate that audio information can be retrieved by applying both amplitude and phase demodulation techniques to the measured common-mode currents when the torque value of the sub-miniature type A (SMA) connectors used in the experiment is set to less than 2.00 cNm.