Fiber optic acoustic transducer intrusion detection system

An intrusion detection system for sensing mechanical and acoustical vibrations in a room having walls, comprising:

• a light source for generating first and second light beams at a point remote from the room;
• first means, operatively connected to said light source and positioned in the walls, for modulating the intensity of the first light beam in response to mechanical or acoustical vibrations;
• second means, operatively connected to said light source and positioned outside the room, for modulating the intensity of the second light beam in response to mechanical or acoustical vibrations;
• third means, coupled to said first and second means, for converting the first and second modulated light beams into first and second detection signals, respectively;
• and
• fourth means, operatively connected to said third means, for comparing the timing of the first and second detection signals to determine whether the mechanical or acoustical vibrations corresponding to the first detection signal, originated inside or outside the room, and for generating an intrusion signal only in response to mechanical or acoustical vibrations generated within the room.

An intrusion detection system for sensing mechanical and acoustical vibrations generated within an area to be protected, comprising:

• a light source for generating first and second light beams at a point remote from the area to be protected;
• first means, operatively connected to said light source and positioned within the area to be protected, for modulating the intensity of the first light beam in response to mechanical or acoustical vibrations;
• second means, operatively connected to said light source and positioned adjacent the perimeter of the area to be protected, for modulating the intensity of the second light beam in response to mechanical or acoustical vibrations;
• third means, coupled to said first and second means, for converting the first and second modulated light beams into first and second detection signals, respectively;
• and
• fourth means, operatively connected to said third means, for comparing the timing of the first and second detection signals to determine whether the mechanical or acoustical vibrations corresponding to the first detection signal, originated inside or outside the area to be protected, and for generating an intrusion display signal only in response to mechanical or acoustical vibrations generated within the area to be protected.