Abstract: A system and method of discerning human intrusion from animal presence without compromising sensitivity to human intruders exhibiting low intensity infrared signatures. At least four infrared sensing elements are arranged with at least one horizontal pair and at least one vertical pair, such as within a quad-sensing element device. To generate an intrusion alert in a pet-immune mode, simultaneous changes in infrared energy must be registered in at least two vertically adjacent detection zones spanning two tiers of sensing elements, corresponding to detecting a standing or semi-standing human intruder. Intrusion is generated in a non-pet-immune detection mode in response to registering sufficient infrared activity within any one or more individual detection zones. The focal lengths of the lens elements and position of the lens tiers are configured to produce a vertical separation of detection tiers sufficient to prevent a pet from simultaneously occupying space in two vertically adjacent detection zones.

Abstract: A tamper resistant magnetic contact switch apparatus for alarm systems that has a plurality of magnetic reed switches configured in a logic circuit and a magnetic pack for actuation. A magnetic shield disposed around the switches defines an actuation zone. In combination with the magnetic shield preventing magnetic fields from reaching the switches from locations outside the actuation zone, the magnet pack activates two of the five switches when positioned within the actuation zone to complete the logic circuit. The magnet pack does not, however, activate any of the other switches. If any of the other three switches are activated, or if either of the two activated switches are deactivated, the logic circuit is broken and the alarm circuit is activated.

Abstract: A tamper resistant magnetic contact switch apparatus for alarm systems that has a plurality of magnetic reed switches configured in a logic circuit and a magnetic pack for actuation. A magnetic shield disposed around the switches defines an actuation zone. In combination with the magnetic shield preventing magnetic fields from reaching the switches from locations outside the actuation zone, the magnet pack activates two of the five switches when positioned within the actuation zone to complete the logic circuit. The magnet pack does not, however, activate any of the other switches. If any of the other three switches are activated, or if either of the two activated switches are deactivated, the logic circuit is broken and the alarm circuit is activated.