No abstract

Tripwire-operated fragmentation mines can be a significant hazard for deminers, especially during vegetation clearance. Several different technologies including thermal, acoustic, and electromagnetic have been evaluated as possible candidates for use in a reliable longrange detector which can find tripwires completely obscured by vegetation. An acoustic method has been proposed to detect non-metallic tripwires. The results of some experimental measurements using this approach are presented. Taut, non-metallic wires can be stimulated acoustically so as to generate a characteristic frequency component which may enable detection.

A new expression for the attenuation of a radio wave propagating over a mixed land-sea path successfully predicts the recovery of field strength over the sea path. An initial series of measurements has been made in the Auckland area to determine whether recovery effect is a significant factor at cellular radio frequencies. Some evidence for this has been obtained.