RADIO BEAM ALARM DETECTOR Russian patent published in 1997 - IPC

FIELD: alarm systems for protection of perimeters of monitored areas against intruders. SUBSTANCE: device has clock oscillator, dividing counter, generator of linearly varying voltage, microwave oscillator, antenna, mixer, amplifier, band-pass filter, frequency analysis unit which has two groups of selective channels and first final-control unit. In addition device has self-test unit, synchronization frequency synthesizer, circulator, commutator, decoder, three- position switches, AND gates, OR gates, second final-control unit. Comparator of amplitude priority is controlled by clock oscillator. Frequency analysis unit has additional voltage adder and threshold gate. Each selective channel of first group in frequency analysis unit has serial circuit of clock detector, low-pass filter and amplifier. Each selective channel of second group in frequency analysis unit has clock signal detector, low-pass filter, first amplitude detector, Doppler signal filtering amplifier and second amplitude detector. Monitored area is divided into N independent pieces in arbitrary combination without dead area. In addition possibility to lock equipment of radio beam detector due to natural or artificial causes is excluded. In addition device provides no possibility to miss intrusion in nearest area and to lock area by means of setting screen which is non transparent to radio waves. EFFECT: increased reliability, detection and increased functional capabilities. 3 cl, 7 dwg