Investigation of Unintentional Video Emanations From a VGA Connector in the Desktop Computers

• Published in: IEEE transactions on electromagnetic compatibility Vol. 59; no. 6; pp. 1826 - 1834
• Main Authors: Zhang, Nan, Lu, Yinghua, Cui, Qiang, Wang, Yiying
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.12.2017; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Adapters; Antennas; Compromising emanations; Computational modeling; Computer simulation; Computers; Emission; Field tests; Leakage; Liquid crystal displays; liquid-crystal display (LCD) computer; Personal computers; Pins; TEMPEST; video signals; Wire; wire antenna model; Wires
• ISSN: 0018-9375; 1558-187X
• DOI: 10.1109/TEMC.2017.2699479

This paper focuses on the compromising video emanations from a desktop computer with a liquid-crystal display (LCD). Near-field tests are performed in a common unshielded office environment to investigate the video information leakage, and the tests show that the video graphics adapter (VGA) connector is a leaking source. To illustrate the mechanism of the video leakage, a wire antenna model is developed according to the physical dimensions of the connector. The radiated fields of the connector are calculated in the time domain from this model, the results are verified by the tests. Combining the expressions of the radiated fields and the transfer function of the test probe, the function relationship between the original red/green/blue signal and the intercepted signal is established. Finally, a readable text is reconstructed from the intercepted signal when a Chinese document is displayed on the LCD.