SECURITY ALARM DEVICE Russian patent published in 1998 - IPC

FIELD: automatic equipment for guarding premises. SUBSTANCE: method involves emission of microwaves towards guarded premises by means of generator, and receiving these microwaves after their multiple reflection from objects which are located in guarded premises. Goal of invention is achieved by amplitude-frequency or phase-frequency response processing from regions in guarded premises and comparison of generated signal to received one. When additional object of arbitrary size appears in guarded premises, as well after alternation in interior, such as absence or arbitrary velocity movement of objects, reflected signal contains constituent with new amplitude and phase which alter amplitude- frequency and phase-frequency response from regions in guarded premises. Upon comparison of amplitude-frequency or phase- frequency response to initial one, microprocessor unit generates alarm signal according to given criteria. EFFECT: increased sensitivity to alternation of interior in guarded premises and sensitivity to alternation of interior in every point inside guarded premises. 1 dwg