Abstract: A system for detecting intrusions into a protected area by personnel, vehicles, or other objects, including a sensor capable of detecting magnetic and/or pressure disturbances and a signal processing means for generating an alarm signal when an unwanted intrusion occurs. The signal processing apparatus includes a first band-pass filter for selecting the portion of the signal from the sensor which is within a first frequency range, and a second band-pass filter for selecting a portion of the signal within a second frequency range. Logic circuitry is provided to process the two analog signals from the two band-pass filters using amplitude, signal energy and zero-crossing characteristics of the two signals in a cross-channel relationship to eliminate false alarms which might be caused by disturbances such as lightning, thunder, or wind.

Abstract: The present apparatus is designed to determine the presence of an intruder in a swimming pool by detecting a predetermined change in water level caused by displacement. The surface of the pool water forms the lower boundary of an air filled acoustic cavity, and cavity resonance is excited therein by a sonic transducer coupled to the cavity and also to a signal amplifier, causing the cavity to determine the frequency of oscillation of the feedback amplifier. A rise in water level caused by intruder displacement decreases the vertical dimension of the cavity so that the cavity has a different resonant frequency than before intrusion, and the amplifier therefore oscillates at a different frequency. The predetermined change in amplifier signal output frequency is sensed by an electrical network and converted to an alarm device activating signal to indicate an intrusion.

Abstract: A circuit for an infrared intrusion detector comprising a plurality of receiving directions or regions which are separated from one another and a radiation receiver, at the output of which there appears an electrical signal corresponding to the infrared radiation which is absorbed by all of the receiving directions or regions. The circuit is structured such that an alarm signal is delivered when the received infrared radiation both ascends in a predetermined manner as well as descends in a predetermined manner within a given delay time.

Abstract: A charge-sensitive switch is described sensitive to the adjacency of, or transfer of charge from a person, for controlling lamps, appliances, motors, etc. The switch contains an over-current sensor for detecting excess load current, and takes action to shut off the current. It can also switch successive loads, as would be required in a tri-light lamp. The input sensitivity of the switch is adjustable so as to be able to switch in the presence of an adjacent charge, as would be required for proximity detection in a burglar alarm.

Abstract: A personal security device incorporated into a conventional flashlight for informing a person, by remote control means, who is outside the door of the house, and indicating by a picture, whether it is a man, woman or child, the picture appearing on a view screen of a unit mounted on the flashlight, so that a person is thus cautioned against opening the door, particularly if there is a man outside.

Abstract: A shielded two-wire cable used to transmit signals from one or more remote receivers to a central signal processing unit in an energy-responsive system is simultaneously used to transmit from the signal processing unit to the receivers (a) a signal proportional to the system noise level, (b) a pulsating signal when the system noise exceeds a level indicative of a desired margin of safety, and/or (c) a steady-state signal when an alarm signal is generated by the signal processing unit.

Abstract: A spring within a container is maintained in compression by a first movable pin that extends from the inside to the outside of a container. In response to the first pin being pulled from a set position, a spring drives a hammer against a dispensing button of a tear gas cannister whereby the cannister dispenses tear gas. Additionally, a second pin extends from the inside to the outside of the container. In response to the second pin being pulled from a set position, a switch causes the application of a voltage of a battery to a horn whereby the horn emits sound.