Abstract: A keyless entry system has means for defining an interrogation zone. A marker responsive within the interrogation zone to generate a coded signal cooperates remotely with means for disengaging a locking mechanism upon verification of the coded signal when received.

Abstract: An acoustic transducer is provided that uses a layer of magnetostrictive ferromagnetic material having high magneto-mechanical coupling. The ferromagnetic material is adhered to a part of the outer surface of a resilient rod, so that an incident acoustic signal causes a change in stress in the magnetic material and, in turn, a change in the material's magnetization. An electrical coil surrounds the magnetic material and converts the changing magnetization into an electrical signal. A plurality of transducers may be assembled into an array and towed behind a ship to detect underwater acoustic signals.

Abstract: A magnetic article surveillance system marker is adapted, when armed, to resonate at preselected frequencies provided by an incident magnetic field applied within an interrogation zone. The marker is a plurality of elongated ductile strips of magnetostrictive ferromagnetic material each of the strips being disposed adjacent to a ferromagnetic element which, upon being magnetized, magnetically biases the strips and arms them to resonate at the preselected frequencies. A substantial change in effective magnetic permeability of the marker at the preselected frequencies provides the marker with signal identity.

Abstract: A magnetic article surveillance system marker is adapted, when armed, to resonate at a frequency provided by an incident magnetic field applied within an interrogation zone. The marker is an elongated ductile strip of magnetostrictive ferromagnetic material disposed adjacent to a ferromagnetic element which, upon being magnetized, magnetically biases the strip and arms it to resonate at said frequency. A substantial change in effective magnetic permeability of the marker at the resonant frequency provides the marker with signal identity.

Abstract: A temperature-sensitive switch is provided with a resilient movable cantilever composed of amorphous ferromagnetic material having a Curie point. The cantilever is adapted to carry a first contact member. A second contact member is disposed adjacent the first contact member for at least intermittently establishing electrical contact with the first contact member. A magnet is associated with and adapted to bias the cantilever to a first position that establishes electrical continuity between the first and second contact members. The cantilever is transformed from a ferromagnetic phase to a paramagnetic phase when its temperature exceeds the Curie point, whereby the cantilever assumes a second position in which the electrical conductivity is interrupted. The switch is lightweight, compact, economical to manufacture and reliable in operation.