Omnidirectional ultrasonic intrusion surveillance unit

• US 3,961,321 A
• Filed: 01/24/1975
• Issued: 06/01/1976
• Est. Priority Date: 09/17/1973
• Status: Expired due to Term

• Current Assignee: Royston Arthur Leslie Moss
• Original Assignee: Royston Arthur Leslie Moss
• Inventors: Moss, Royston Arthur Leslie
• Primary Examiner(s): Swann III, Glen R.
• Application Number:
  US05/543,821
• Time in Patent Office: 494 Days
• Field of Search: 340/258 B, 340/258 A, 340/258 R, 343/7.7, 343/5 PD, 343/6 R
• US Class Current: 367/93
• CPC Class Codes: G08B 13/1627 using Doppler shift detection circuits

Abstract

An omnidirectional ultrasonic intrusion surveillance unit can be suspended or supported in a room or like closed environment so that there is space substantially all round the unit, permitting surveillance all around the unit, that is, over substantially 4π steradians, simultaneously. Ultrasonic waves are generated by an oscillator and radiated via an arrangement of transducers in a plurality of directions in the space surrounding the unit. The reflected waves are received from substantially all directions in the space by a transducer system associated with the wave radiating transducers, and a detector is provided to sense variations in the received reflected waves. Amplified signals produced by the detector in response to any such variations are applied to a trigger unit having a predetermined reference level indicative of intrusion disturbance of the wave field, and an external alarm is placed in operative condition if the level is exceeded.

Claims

1. An omnidirectional ultrasonic surveillance unit for used in a closed environment and comprising:

a substantially closed shell forming a housing;

means for supporting the housing away from any ceiling, walls and floor of the closed environment so that there is open space substantially all around the housing;

means for radiating oscillatory energy at an ultrasonic frequency in substantially all directions from said surveillance unit so that the open space all around the housing is filled with sound waves;

said housing being adapted to vibrate in response to reflected sound waves impinging thereon;

receiver transducer means connected to the inside of said housing for sensing vibration thereof and for generating an oscillatory electrical signal in response thereto; and

electrical circuitry inside the housing, said electrical circuitry including;

means for generating said oscillatory energy inside the housing and for driving said radiating means;

means for amplifying the oscillatory electrical signal generated by said receiver transducer means;

discriminator means for producing a variable DC signal responsive to amplitude variations in the amplified oscillatory electrical signal from the amplifying means;

low frequency amplifier means for amplifying low frequency signals from said discriminator means; and

means responsive to the output from said low frequency amplifier means for producing an electrical alarm-operating signal.

2. A surveillance unit as defined in claim 1 wherein said alarm-operating signal-producing means comprises:

means for producing shaped pulses in response to said low frequency amplifying means;

means responsive to a first pulse from said pulse-producing means to commence timing a counting period;

means for counting the number of pulses from said pulse-producing means during the counting period;

and means for producing said alarm-operating signal only if the number of pulses counted during the counting period by said counting means reaches a predetermined minimum number.

3. A surveillance unit as defined in claim 1 wherein said electrical circuitry includes means responsive to loss of signal from said discriminator means for producing said alarm-operating signal and means responsive to signal saturation from said discriminator means for producing said alarm-operating signal.

4. A surveillance unit as defined in claim 1 wherein said housing supporting means comprises a support rod joined to and extending away from said shell.

5. A surveillance unit as defined in claim 1 wherein the shell is formed with at least one port-hole and wherein said radiating means comprises at least one respective sonar transducer located in said at least one port-hole.

6. A surveillance unit as defined in claim 1 wherein said shell is substantially spherical.

7. A surveillance unit as defined in claim 2 wherein said electrical circuitry includes means responsive to loss of signal from said discriminator means for producing said alarm-operating signal and means responsive to signal saturation from said discriminator means for producing said alarm-operating signal;

wherein said housing supporting means comprises a support rod joined to and extending away from said shell;

wherein the shell is formed with at least one port-hole and wherein said radiating means comprises at least one respective sonar transducer located in said at least one port-hole; and

wherein said shell is substantially spherical.