A 33‑zones door‑frame metal detector (33‑zone DFMD) is a premium high‑precision multi‑zone screening device for mission‑critical security guard systems. Compared with 18‑zone models, this high‑end equipment divides the full‑height archway into thirty‑three independent overlapping vertical‑horizontal detection zones. When concealed metal weapons or forbidden metal articles are detected, corresponding LED zone indicators on both left and right sides illuminate to show ultra‑fine‑grained height plus left‑right position of metal threats on human bodies. Security staff can then use a handheld metal detector to pinpoint suspicious spots with minimal scanning range, maximizing pedestrian throughput at high‑security checkpoints. Sintronic 33‑zones door‑frame metal detectors have been delivered for overseas security projects including the Colombia shipment reference project.

Core Working Principle of 33‑Zones Door‑Frame Metal Detector

Sintronic 33‑zones door‑frame metal detector adopts advanced digital pulsed‑induction electromagnetic technology. Large quantities of independent transmitter‑receiver coil pairs are embedded on both sides of the arch frame to form thirty‑three separate overlapping detection sections, covering full‑body area from head down to feet with minimal blind spots. The complete detection workflow is shown below.

1. Power‑on self‑check & multi‑zone magnetic‑field generation

After power‑on initialization and full self‑diagnosis, each of the thirty‑three coil groups generates stable pulsed low‑frequency electromagnetic field, covering different vertical‑horizontal segments across the passage. Operators can configure independent sensitivity parameters for every single zone according to strict high‑security project requirements. Multiple preset screening profiles are available for quick scene switching.

2. Magnetic‑field disturbance triggered by metal objects

When a pedestrian walks through the archway carrying concealed metal items, eddy currents will be induced inside the metal. It generates reverse secondary magnetic field and disturbs local electromagnetic field of one or several detection zones. Only receiver coils of disturbed zones capture abnormal signal data.

3. DSP signal processing & zone‑targeted alarm trigger

Built‑in high‑performance DSP digital signal processor analyzes signal amplitude from each of the thirty‑three zones separately. Once the signal exceeds preset sensitivity threshold, the detector activates combined audio‑visual alarm: buzzer beeps, meanwhile the LED indicator lights corresponding to disturbed vertical‑horizontal zones illuminate on both sides of the arch.

4. Reset and prepare for next pedestrian screening

After security personnel finish secondary inspection and handling for alarmed persons, the detector automatically resets all zone status and stands by for the next passing‑through pedestrian.