System and method for spectral-based passive threat warning

A method of classifying an electromagnetic-energy emitting source event as one of (i) a first class event, (ii) a second class event and (iii) a third class event, the method comprising:

• providing a data processing system including a central processor and at least one memory device communicatively linked to the central processor;
• providing a spectral sensor and communicatively linking the spectral sensor to the data processing system, the spectral sensor being adapted to detect electromagnetic wavelengths over a predetermined wavelength range;
• providing an optical system including at least one dispersion element and being configured to disperse constituent wavelengths of polychromatic energy emitted from a source event external to the optical system such that disparate wavelengths of interest emitted by the source event impinge upon different impingement locations on the spectral sensor;
• defining first, second and third classes of emitting source events;
• maintaining, in computer memory, a modeled spectral data set including spectral irradiance data indicative of the relative intensities of remotely measurable electromagnetic energy associated with at least one model source-event at various selected wavelengths and providing, relative to each model source-event, spectral data from which an expected ratio-comparative relationship between energy intensities is ascertainable for a selected set of wavelength sub-ranges within a model irradiance spectrum;
• registering, at the spectral sensor, a spectral irradiance signature of the electromagnetic-energy emitting source event and storing a registered-data set indicative of the registered spectral irradiance signature in computer memory;
• consulting the registered data set for the algorithmic analysis of at least first, second and third selected wavelength sub-ranges of the registered spectral irradiance signature represented by the registered-data set and associating with, respectively, the selected first, second and third wavelength sub-ranges, first, second and third relative-energy values, wherein each relative energy value corresponds to the intensity of energy registered at the spectral sensor within the wavelength sub-range with which that relative-energy value is associated;
• comparing to one another a first selected set of two of the relative-energy values;
• rendering a first class-eliminating determination that the emitting source event is not within a selected one of the first, second and third event classes based on whether a selected one of the relative-energy values included in the first selected set of two relative-energy values is one of (i) greater in magnitude and (ii) lesser in magnitude than the other of the relative-energy values included in the first selected set of two relative-energy values by at least a predetermined first threshold amount;
• and
• depending on the class that is eliminated through execution of the first class-eliminating determination, one of
• (i) terminating the analysis if, from the first class-eliminating determination, it is determined that the emitting source event conclusively belongs to a particular one of the first, second and third classes;
• and
• (ii) if the first class-eliminating determination yields two remaining-candidate event classes, comparing to one another a second selected set of relative-energy values including the relative-energy value not selected for inclusion in the first selected set of two relative-energy values and one of the relative-energy values selected for inclusion in the first selected set of two relative-energy values, and rendering a second class-eliminating determination that the emitting source event is not within a selected one of the two remaining-candidate event classes based on whether a selected one of the relative-energy values included in the second selected set is one of (i) greater in magnitude and (ii) lesser in magnitude than the other of the relative-energy values included in the second selected set by at least a predetermined second threshold amount;
• wherein
• (i) each class-eliminating determination is furthermore based upon consultation with the modeled spectral data set in order to ascertain an expected ratio-comparative relationship as a function of at least both of (a) source-event type and (b) the selected wavelength sub-ranges;
• and
• (ii) a signal indicative of the outcome of each class-eliminating determination is communicated to at least one of (a) a human being and (b) computer apparatus in order to facilitate appropriate responsive action.