A method and apparatus for finding contamination occurrence and for preventing the propagation of the contamination is provided according to the present invention, which altogether constitutes a contamination prevention system. The user is provided with the freedom to input selection ink, in any orientation, and using any desired selection path size provided by the select tool. A second component comprises a body carrying an annular skirt extending coaxially about a longitudinal axis and defining an entry bore, the annular skirt being separated from a surrounding, annular coupling bore wall of the second component by an annular recess therebetween. The simulation unit is configured to provide simulated diffraction spectrums of the at least a via. According to an embodiment, an emission source is located by monitoring an area with one or more sensors, determining a plume, generating one or more candidates for the emission source, and using the plume to derive one or more characteristics associated with the emission source, and then locating the emission source based on agreement or convergence of the one or more characteristics. By properly allocating a local frequency, radio frequency signals of a Global Positioning System, a Galileo positioning system and a Global Navigation System are processed via a single signal path to save hardware cost.