FIELD: radio engineering, communication.
SUBSTANCE: method of determining violation of an air boundary employs frequency radar in the form of one transmitting module and four receiving modules, two phase detectors and four information display units. The receiving module includes a receiving antenna, a mixer, a differential frequency filter, a narrowband spectrum signal detector and an output bus. The method includes mounting a transmitting antenna at the centre of a circle and four receiving antennae on the same circle equidistant from each other; irradiating an intruder with electromagnetic energy; receiving chirp signals reflected from the intruder; multiplying the received and emitted signals in four mixers to obtain four signals with a specific identical differential frequency. Upon detection of said signals, one of four LEDs lights up, said LEDs characterising known distances to the secure air boundary, signalling its violation.
EFFECT: protecting an air boundary.
2 cl
