Electronic fence surveillance apparatus

Abstract

Abstract Electronic fence surveillance apparatus in which a plurality of sections of relatively rigid electrical conduit are supported by the fence serially therealong and independently of the fence posts, the sections being connected by a plurality of liquid tight housings each interposed between and having a threaded liquid tight connection with the adjacent sections of conduit and in which there is a vibration sensor secured in each of the housings and responsive to vibrations transmitted to the housing in which it is located, each of the vibration sensors being effective to produce a vibratory electrical signal upon the conduit being vibrated and transmitting this signal to an indicating device through an electronic network. The vibration sensor is in the form of a piezoelectric element designed to operate within the range of frequencies occurring in the conduit when the fence is disturbed. The conduit is preferably of iron or steel and has a wall thickness of between 0.10 and 0.12 inches so as to have a relatively wide band of frequency transmission with relatively little attenuation. The electronic equipment includes a band pass amplifier between each group of sensors and the indicating device associated therewith. Provision is made for integrating the output of the band pass amplifier. The electronic apparatus may contain a number of band pass amplifiers, each of which is connected to a separate group of the sensors, and there may be two indicating devices, one of which is controlled by all of the band pass amplifiers and the other of which may be selectively connected to the amplifiers one at a time by a suitable selector switch. A flexible coaxial cable extends through the conduits interconnecting the various sensors in any one group to the electronic apparatus.

Inventors

• 👤 Charles R. Dettmann
• 👤 John J. Frederick

Bibliographic Details