Multi-Zone Approach

Intelliscan's horizontal zones, each have two receiver sensors and detection channels. They are represented by the colored bars shown in the picture to the right. Unlike the Intelliscan Eighteen-Zone, the horizontal zones of the Intelliscan Six-Zone are not sub-divided. In all other respects both units are similar.

Although the detection zones overlap, they behave as independent metal detectors. Each has a sensitivity control that allows the detection response within the zone to be either boosted or attenuated with respect to the detector's overall sensitivity. The overall sensitivity of the detector is controlled, for each detection program, by the Baseline Sensitivity Control. The Baseline control adjusts the detection response of all zones equally and can be adjusted in 1% steps over the range 1 to 99%. For example, if the sensitivity of the detection zones are all set to zero percent, the detection response within the zones are neither boosted nor suppressed. The sensitivity of a zone can be controlled in 1% steps over a range from -99 to +99%. Applying a negative value produces a drop in detection response within the zone. Conversely, a positive value makes the zone more sensitive. Changing zone sensitivity has no effect on the other zones.

Intelliscan Six-Zone
displays height at which objects are carried. The sensitivity of its zones are fully adjustable.

The zones can be adjusted to create a uniform response throughout the archway, thus insuring that the targeted object is detected consistently in all regions of the archway. The importance of this is discussed in a later section.

Although multi-zoning may appear to be more complicated, it can greatly simplify the operation and calibration of a detector.

Despite its advanced performance Intelliscan Six-Zone is priced to compete with conventional detectors.

Click to see animation

Intelliscan Six-Zone Display Panel

The Intelliscan Six-Zone display panel shows the height at which one or more objects are carried.

The animation depicts the alarm display as a tall person passes through the unit with a weapon in a shoulder holster and is followed by another person carrying weapons at both shoulder and ankle height.

The bar graph display indicates the size of the object and the severity of any existing ambient electrical or electromagnetic interference.

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.