Patent ID: 7107179

Claim:
A method using a passive target data acquisition system (PTAS) operative from an observation point for passively sighting a target, the PTAS having: passive sighting means coupled to a navigation device and to azimuth and elevation angle measuring devices, a computer module operatively coupled sighting means, and to a display, to a digital terrain model DTM database, to the the method comprising the steps of: measuring location data of the observation point, and azimuth and elevation angle data to the target, and feeding measured data to the computer module and presenting on the display both the observation point and the target on a corresponding DTM surface derived from the DTM database, the method comprising the steps of: directing a vector toward the target and defining an envelope surrounding the vector originating at the observation point, and an envelope mantle distanced away from the vector proportionally to errors of measurement, running a PTAS computer program on the computer module for calculating intersection points of the vector and of the envelope with the DTM surface, and presenting the intersection points and associated information on the display, whereby target data is acquired passively to avoid emission of radiations.