Geophone technology - works best trenched.

How would you recommend applying geophone technology in perimeter security application?

A: The right way to use geophones is to have them trenched and buried. Geophones provide high security protection with low false alarm rates so long as there are no stray passers-by coming anywhere near the boundaries. Burying these sensors should be carried out carefully. Security managers and project managers overseeing geophone trenching should never ask the install team to cut corners.

Geophone trenches must be about 300mm wide and 150-300mm deep. Where flat-based geophones are used, go for a 300mm trench and backfill with pea gravel or sand to 100mm before laying the geophone and cable and adding another 100mm of sand and then 100mm of earth tamped 10mm below ground level. This surface should then be planted with grass or covered with gravel to form a sound box.

Spike geophones can be used in shallower trenches. They’re pressed into the base of the trench and then backfilled with layers of sand, gravel and earth. Depending on who installs the system, it’s recommended that security contractors carry out or supervise backfilling. Backfilling forms part of the sensor and should not be underestimated in terms of the system’s sensitivity.