|
Intelliscan Compensates for Detection Losses Caused by Re-bar in Floors
The zone sensitivity controls permit accurate sensitivity adjustments throughout the vertical axis of the archway. In the case of re-bar in a floor, this is achieved by increasing the ground zone's sensitivity to a level that enables the targeted weapon to be detected at floor and ankle height. Increasing ground zone sensitivity has no impact on the upper zones and, unlike a single zone detector, no hot regions are created. The end result is that uniform detection can be established from the top to the bottom of the detector and the baseline sensitivity can be adjusted to provide optimal detection. Optimal detection occurs at the lowest sensitivity that permits consistent detection of the targeted weapon or object.
Suppressing the detection response of a zone can be useful. At a plant where the workers wear safety shoes with metal toe caps, the response of the ground zone can be lowered to prevent alarms from their shoes.
For further information on cumulative signal effect, detector uniformity and discrimination refer to "Understanding Basic Metal Detection" in Information web page. This article also addresses the economic implications of increasing screening rates.
Horizontal Axis Gain Control
While multi-zone detection provides an excellent method of compensating for detection losses caused by structural steel in a floor or ceiling, it fails to compensate for detection losses caused by vertical standing metal positioned adjacent to a detector's side panel. Ranger's new generation detectors include a feature called Horizontal Axis Gain Control (HAGC.) When a detector is operated in proximity to a metal object, such as a steel girder, distortions occur in the detection field and non-uniformity of detection appears. This results in the detection response on one side of the archway deteriorating. The effect is analogous to the non-uniform detection caused by re-bar in a floor, however, the effect is across the zone rather than vertically. HAGC permits the detection response across each zone to be precisely adjusted and under most conditions detection uniformity can be restored.
Because each zone performs independently, compensation can be accurately applied to those regions of the archway that specifically need it. This factor is important, as the external metal may only influence part of the detection field. Some conventional detectors can be adjusted in the horizontal axis, which results in the compensation being applied across the full height of the detector. This feature is useful if the external metal extends the full height of the detector, however, it is counter productive if only part of the archway is affected. | 
