Sound-type detection system

Claim 1

An intrusion and mechanical disturbance detection system comprising a plurality of sending units, one said sending unit being located in each area to be monitored and each of said sending units including detecting means for detecting acoustical energy generated within a protected area and for converting detected acoustical energy into electrical energy, at least one of said detecting means comprising a means for sensing sounds such as made by intruders entering a protected area and a means for detecting mechanical disturbances and producing a corresponding audio output, said sending units further comprising amplifier means for converting said electrical energy into an amplified electrical signal; a monitoring station comprising electrical monitoring means for monitorIng said plurality of sending units; and transmitting means for transmitting a said electrical signal from a protected area to said monitoring station, said monitoring means comprising a plurality of audio monitors individual to said sending units and an indicator device common to said plurality of monitors, a common power supply for said plurality of monitors, and a common output transducer for said plurality of monitors for converting a said electrical signal into an acoustical signal and a common amplifier for amplifying the input to said common output transducer, said transmitting means comprising telephone lines connected between said sending units and said monitors and said sending means including means for connecting the associated detecting means to the corresponding telephone line, said mechanical disturbance detecting means comprises a first means for detecting mechanical disturbances of a first type and a second means for detecting mechanical disturbances of a second type, said first means causing actuation of a first device for producing a characteristic sound and said second means causing actuation of a second device for producing a characteristic sound different from the sound produced by said first device, said first mechanical disturbance detecting means comprising power failure detecting means for detecting a power failure for a three-phase system, said power failure detecting means including first and second relays, first and second sets of relay contacts and an independent source of power for said first sound producing device, said first relay being connected between neutral and a first phase conductor of the three-phase system and said second relay being connected between the remaining two phase conductors of the three-phase system and the first and second sets of relay contacts controlled by said first and second relays completing, in the actuated state thereof, a circuit between a said sending unit and the transmitting means connecting said sending unit to a corresponding monitor, and completing, in the unactuated state thereof, a circuit including said first sound producing device, said independent source of power, and said transmitting means.