Fixed extensometer is a single rod extensometer, usually defined as device placed in embankment fill or inside borehole for monitoring of settlement or heave between two points without use of a removable probe.
Either the Settlement Platform and the Tell-Tale extensometer are based on a riser settlement rod which is respectively connected to a plate buried at the embankment foundation level or grouted inside borehole as a deep benchmark in a firm soil.
Optical levelling measurements to the top of the riser rod provide precise monitoring. Electrical transducer can be used for remote readings without the need of survey crew.
DEX is a Sisgeo technology designed to monitor the displacement along the main axis of a special tube.
DEX is based on a special linear transducer able to detect with high accuracy the position of a magnetic ring installed on the measuring tube.
The DEX sensor is able to read the movements of the ring, generally caused by external forces.
DEX can work in vertical, horizontal or any inclined position.
The measuring tube is an ABS inclinometer casing that do not interfere with the magnetic field generated from the magnetic ring.
DEX-S is a combination of DEX and MEMS technologies that allows to measure 3D boreholes deformations.
A linear potentiometer is a device with a movable slider, usually called wiper, that makes electrical contact along a fixed resistance strip. A regulated DC voltage is applied to the two ends of the resistance strip: the voltage between one end of the strip and the contact point of wiper and strip is measured as the output signal.
Sisgeo instruments that utilize linear the linear potentiometer technology have often a 4-20mA output because electrical (Ampere) signals are more suitable for long distance transmission than tension (Volt) signal.