Laser printer as a source of sensitive emissions


Abstract: Each electronic (electric) device generates electromagnetic emissions during its operation. Most often these emissions are generated unintentionally and they are radiated into the surrounding space in an uncontrolled way. In the case of significant levels of these emissions, they can disturb the operation of other devices or can be used as typical radio emissions. If the nature of their changes corresponds to the processed information occurring in a form of electric signals, the mentioned emissions can be a basis for effective realization of electromagnetic infiltration processes. Most often, these emissions are classified in laboratory conditions using anechoic chambers. Inside such chambers there are not additional sources of emissions that would increase the level of electromagnetic protection through disturbance of sensitive emissions. The sensitive emissions have distinctive features corresponding to the processed information. Using these emissions, the reconstruction of primary information is possible. This article presents the results of tests of a laser printer with a two-diode laser system, operated in an open space and in office rooms, outside the anechoic chamber. These are so-called real conditions of operation of the device. The purpose of the tests was to show the existence of risks in a typical electromagnetic environment. Additional sources of emissions or occurring obstacles, e.g., walls of offices, do not reduce levels of sensitive emissions to safe values. The electromagnetic infiltration process is possible in each of the mentioned environments and its effects are presented in the form of reconstructed images. The distances on which the compromising emissions are measured deserve special attention. They are equal to even several meters.

Keywords: Reveal emission, protection of information, range of leakage of information, electromagnetic eavesdropping, sensitive emission

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