Analysis of the Compromising Audio Signal From the Emission Security Perspective

This paper describes the process of detecting secondary electromagnetic radiation generated by a portable personal computer when it plays audio signal in the loudspeakers. To facilitate the detection of secondary emissions, 3 simple audio test models consisting of two, three and four audio tones were favorably selected. The reception and demodulation of these test signals were successful at frequencies far superior to the audio frequencies range. Measurements in the time domain were also performed in order to confirm the veracity and quality of the reception as well as the degree of identification.