Patent ID: 8543346

Claim:
A method for analyzing a target electromagnetic signal radiating from a monitored system, comprising: in at least one computer, performing operations for: monitoring the target electromagnetic signal using a near-isotropic antenna comprising a set of receiving surfaces arranged in a regular polyhedron; obtaining a set of received target electromagnetic signals from the set of receiving surfaces, wherein obtaining a set of received target electromagnetic signals comprises receiving each electromagnetic signal as the electromagnetic signal arrives from a direction in which a corresponding receiving surface of the antenna faces; and assessing the integrity of the monitored system by separately analyzing each of the received target electromagnetic signals, wherein separately analyzing each of the received target electromagnetic signals comprises, for each receiving surface in the set of receiving surfaces, using a separate reference model for the receiving surface and at least one of the target electromagnetic signals received at the receiving face to produce an estimated electromagnetic signal fingerprint for the at least one of the target electromagnetic signals.