Abstract: A high security ultrasonic receiver apparatus including a rigid metal faceplate having an ultrasonic sensor affixed to the rear side thereof and adapted to sense acoustical energy transmitted to the faceplate. The faceplate has no apertures through which acoustical energy is intended to be communicated to the transducer. All acoustical energy is mechanically coupled to the transducer. The plate is further adapted to be affixed to a wall or wall receptacle in a manner similar to that of a standard electrical switchplate or plug socketplate. The transducer and associated electronic components are adapted to be electrically connected to a remote annunciator in a conventional manner.

Abstract: An improved device for generating an ultrasonic signal for use in an area protected by an alarm actuated by an ultrasonic signal. The device includes a tuned, acoustic rod within a cylinder typically about the size of a pen adapted to be worn in a shirt pocket. The device has a spring-actuated hammer which is movable, when triggered, into engagement with the rod to generate an acoustic signal. When the hammer is cocked, it is held in a cocked position by two spaced triggers which must be actuated simultaneously to release the hammer to cause it to move toward and to strike the rod. The cylinder has an opening for indicating the fact that the hammer has been triggered. The device is made so that it cannot be re-cocked without special equipment not available to the public.