Unattended ground sensors with screw thread for aiding installation into the ground

摘要

An unattended ground sensor unit has a body portion 1 and a head portion 2. The body portion has a screw thread 7 on and around an external surface so that a rotation about the main axis will tend to draw the sensor unit into the surrounding ground in order to improve the acoustic coupling of the unit to the ground. The body portion 1 is generally hollow and a battery 3, a sensor 4, an antenna 5, and control electronics are provided therein. The head portion 2 may include engagement recesses or flats (26, fig.1; figs 3&4) for cooperation with a toothed tool or hexagonal spanner (8, figs 5A, 5B) for installing the sensor unit. The sensor unit may include a seismic sensor, acoustic sensor, magnetometer, heat or light sensors and may be used in a network of such sensors for detecting the movement of a person or object.