US Government As Represented by the Secretary of the Army

Other

Gilbert F Wagner

J Louis Berger

Arthur C Tiemann

A strain sensitive coaxial cable is disclosed as comprising a centrally dosed conductor about which is disposed a first insulating layer, and a second conductor disposed coaxially about the center conductor, configured as a helix and dimensioned to loosely fit with respect to the first dielectric layer and to permit relative axial movement generally between the second conductor and the first dielectric layer, whereby more uniform signals, and elastic-inelastic strain discrimination are provided and spurious outputs eliminated. An outer protective sheath is disposed about the helical turns of the second conductor. Another form includes using spaced mechanical means such as collar members at spaced intervals frictionally affixed to both the dielectric layer around the center conductor and the second helical conductor to prevent movement of those frictionally engaged spaced portions of the second conductor with respect to the dielectric layer around the center conductor, thereby reducing the possibility of providing false or spurious outputs due to strain relief of the cable.

Strain sensitive cable

A dual signature perimeter detection system utilizing an elongated solenoid ype transducer having a ferromagnetic core as a line sensor is buried in the ground around an area to be protected against intrusion. One end of the transducer is impressed with constant frequency oscillator signals from a signal generator, while a resistance load impedance is connected across the other end of the transducer at the input side of an amplifier used to pass amplified signals selectively to the inputs of either a bandpass type filter or an A.M. detector, or to both simultaneously, then to their related alarms. The line sensor is sensitive to both magnetic and strain stimuli, but the system hereof, which utilizes dual alarm devices, not only provides for determining the type of stimulus creating the signals, but also improves the sensitivity and response uniformity of the transducer. Optimized oscillator frequency selection, transducer shielding, and subsequent filtering at the input to the electronics collectively minimize false alarms from otherwise potentially greater noise pick-up due to the system's use of an increased bandwidth.

Apparatus for discriminating between strain and magnetic stimuli in

Three different embodiments of the ultrasensitive differential point contact relay configuration of this invention are disclosed. The first or basic embodiment is particularly suited for use in intrusion detection systems or as a strain gauge/accelerometer and the like. The second embodiment is particularly suited for use as an ultrasensitive electrically actuated relay and the like. The third embodiment performs the function of an ultrasensitive strain gauge/accelerometer whose output is the mix of the mechanical and electrical stimulus. The basic embodiment comprises a point contact relay housed in a two section case or container. The two sections of the container are joined by a lower modulus section. A movable contact arm is spring biased against a second movable contact and the base of the contact arm floats in a viscous fluid. In the second embodiment the case or container is formed as one section and a piezoelectric crystal is mechanically coupled to the second contact. In the third embodiment the case or container is similar to the case or container of the basic embodiment and a pair of transducers are mechanically coupled to the second contact.

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Vienna, VA, United States of America

Gilbert F Wagner