Abstract: An intrusion sensing line to be buried or emersed in a medium and operative to deliver electrical signals in response to pressure changes as the medium is stressed, the line including multiple metal shells each having a transducer bonded to a flexible diaphragm surface inside the shell, and the shells being spaced apart and joined by soft metal tubing, the tubing and shells being metal-to-metal bonded at all joints and sealed to retain a dry inert gas, and the transducers being insulated from the shells to which they are bonded and wired together, preferably with alternating polarities, by insulated wiring extending through the tubing and the shells.

Abstract: An intrusion detecting sensor assembly comprising a bracket having one leg to be clamped to the surface of a structural member, for instance of a building, and having a second leg spaced from the first leg and also abutting said surface, the second leg being joined to the first leg by a bridge portion of the bracket supporting a piezoceramic transducer which is sensitive to bending of the bridge portion when the structural member is flexed by changes in its loading.

Abstract: A cable supporting along its length one or more detector units, each comprising a bendable board which is much longer than it is wide and which supports near its center a piezoceramic transducer whose output is responsive to bending of the board, the cable being bared in the vicinity of each transducer and having its conductors connected with the two terminals of the piezoceramic transducer, the board and the portions of the cable immediately adjacent to the board being unitized by a heat shrunk tube which tightly conforms to the board and said cable portions and unifies them so that they become part of the cable with commensurate stiffness.