Theory of Operation
The D-Guard sensor operates as a linear induction generator whereby precision made concentric conductors within the sensor are arranged to vibrate in a static magnetic field generated by flexible ceramic magnetic profiles.
Mechanical vibrations resulting from intrusion activity are coupled into the sensor through direct contact between the sensor and the protected structure (fence, wall, railing, etc.).
The mechanical energy of vibration is converted to an electrical signal by the sensor by induction of electrical currents into the precision conductors within the sensor.
The electrical signal created by the sensor is an accurate representation of the mechanical energy which created the signal. This enables the signal analyzer module to which the sensor is connected to reliably classify the signals as either hostile, intrusion related signals, or non hostile signals such as those caused by wind, rain, hail, or other environmentally related activity
Unsurpassed Signal to Noise Performance
The smallest intrusion related mechanical activity detected by the sensor will generate a signal level typically 1000 times greater than the background electrical noise level generated by the sensor itself. This unsurpassed audio performance ensures that minute levels of intrusion related activity can be easily extracted and identified by D.O.G - Sec signal analyzer systems without risk of losing such critical information within the high background noise levels that characterize many low performance sensors.
Unaffected by moisture penetration
The low impedance design characteristics of the sensor ensure that the performance of the sensor is unaffected by water ingress resulting from cable sheath damage or poorly sealed terminations or joints.
Immune To Electromagnetic Interference (EMI)
The sensor is configured as a twisted pair of conductors which are balanced with respect to ground thereby ensuring rejection of externally generated electromagnetic interference sources.
Resilient To Lightning Induced Damage
The sensor cable design allows electrical isolation of the sensor from the signal analyzer system using custom made transformers to ensure maximum resilience to lightning strikes in the vicinity of the sensor.
Simple Termination & Repair Procedures
Since the sensor relies on only two copper wires for its operation, terminating and splicing the cable is a simple task readily accomplished by any competent electrical service technician using readily available, non specialist tools. A typical Mean Time To Repair (MTTR) figure of 15 minutes is easily achievable.
Ultra High Quality Audio Signal
The low impedance design of the sensor ensures high quality audio signals which, in turn, allows accurate and unambiguous verification of hostile activity by security personnel.
UV Resistant Sheathing Material
The sensor cable is sheathed in a low density polyethylene polymer which is heavily loaded with carbon powder to provide the highest possible protection against sheath degradation by the ultra-violet radiation present in sunlight.
The sensor cable components are carefully chosen to ensure the highest reliability possible so that a typical Mean Time Between Failure (MTBF) figure in excess of 80,000 hours is achievable. Subject to correct installation, the performance of the sensor will not degrade over time, even in extremes of heat and cold.
No Signal Loss In Interconnecting Cables
The low impedance characteristics of the sensor ensures that no significant signal loss occurs even when long interconnecting cables are used between the sensor itself and it’s signal analyzer. This powerful capability allows the signal analyzers to be ‘clustered’ at strategic points on site where power and communications may be more easily provided. A secondary benefit of this capability is that the requirement for power and signaling cabling along the site perimeter is dramatically reduced with consequent reductions in installation cost