Features of detection and measurement of broadband TEMPEST signals

The article is devoted to the technical channels of Transient Electromagnetic Pulse Emanation (TEMPEST) information leakage. Methods of detection and measurement of TEMPEST, as well as broadband signals in general cases are briefly presented. The features of detection and measurement of broadband TEMPEST signals of modern digital interfaces (for example, DVI, HDMI, DisplayPort) are considered. These digital interfaces are selected as the most relevant at the moment, against analog ones that are coming out of mass use (VGA). The review of the main approaches to the identification of such signals is carried out. Detection and measurement of broadband TEMPEST signals is a non-trivial task, since both TEMPEST signals and broadband signals themselves have a low signal-to-noise ratio. A laboratory stand (an alternative measuring platform) is described in detail, where practical studies were carried out to identify and measure the broadband TEMPEST using the example of the HDMI interface. The influence of the shield camera on the results of research in cases of complete and partial screening of the object under study is demonstrated. The influence of the bandwidth value during measurements of the broadband TEMPEST on the displayed spectrum of such a signal is shown. After reaching a certain value of this bandwidth, the displayed spectrum becomes clearly distinguishable against the background of noise. The measurement of the signal levels of the broadband TEMPEST was carried out in two ways. The first method assumed that the spectrum of the broadband TEMPEST signal is continuous. In the second method, it was assumed that the spectrum of such a signal is discrete. Based on the results of these measurements, a conclusion was made about the actual nature of the spectrum of the signals of the broadband TEMPEST.