The present study was carried out to evaluate the information leakage of a computer display image that can be reconstructed using the conducted emission on its power leads. The reconstructed images can be generated from the relevant signal that was conducted-emitted by the switching of RGB (Red-Green-Blue) signals in the monitor. The relevant signal was then contained in the frequency region higher than 100 MHz in the conducted emission. From these findings, a measurement system was developed to measure the relevant signal in a conducted emission to 1000 MHz. The relevant signals of three PCs were then measured taking account of the signal-to-noise ratio. The measurement results revealed that the relevant signal level depended on the PC and receiving frequency. In addition, the qualities of the reconstructed images were checked using certain receiving frequencies. The reconstructed image quality and the measured relevant signal level were then compared for the same receiving frequency, and a correlation was found.
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