What are the system requirements for DMD?
DMD system operates by generating a controlled magnetic field and measuring very small disturbances in that field caused by objects carried by a person. Because the system is designed to detect extremely weak magnetic signatures, it is inherently sensitive to external electromagnetic interference.
Moving electrical or electromechanical mechanisms close to the system can significantly affect its performance for several reasons:
1. Electromagnetic Interference
Electric motors, actuators, elevators, escalators, automatic doors, HVAC systems, and other moving electrical equipment generate time-varying magnetic and electromagnetic fields. These fields can overlap with the operating frequency range of the magnetometry system and introduce noise that masks or distorts the signals produced by real threat objects.
2. Dynamic Magnetic Field Disturbances
Unlike static metallic structures, moving mechanisms produce changing magnetic fields. DMD system is particularly sensitive to such dynamic variations, as they can be interpreted as target signals, leading to:
Increased false alarm rates
Reduced detection reliability
Unstable system calibration
3. Vibrational and Mechanical Effects
Electromechanical systems often introduce low-frequency vibrations and mechanical movement. These vibrations can indirectly affect sensors, cables, or structural components of the screening system, resulting in signal drift or fluctuations that degrade measurement accuracy.
4. Magnetic Signature of Ferromagnetic Components
Many electrical mechanisms contain ferromagnetic materials (steel shafts, motor housings, gears). When these components move, their magnetic signature changes over time, creating additional interference that cannot be easily filtered out by signal processing algorithms.
5. Impact on System Stability and Calibration
DMD system relies on stable environmental conditions to maintain calibration. Continuous or intermittent operation of nearby electrical mechanisms can cause baseline shifts, requiring frequent recalibration and reducing overall system availability.
Floor requirements:
One of the key installation requirements for discriminative metal detectors is a stable, vibration-free floor. A stable floor ensures a fixed position of the system and the absence of both low-frequency and high-frequency vibrations.
However, floors with a rigid structural design often contain a large amount of massive ferromagnetic reinforcement elements, which create strong field interference in the lower area, particularly near the foot level.
Therefore, when using discriminative metal detectors, it should be noted that there is always a different detection performance in the lower zone, specifically in the leg and floor-adjacent area. In practice, the detection characteristics of any system typically degrade as the target approaches the floor, due to the influence of embedded metal structures within the floor construction
Related Articles
How to Prepare the Installation Site for the DMD System?
To ensure stable and efficient operation of the DMD system, it is essential to choose the right installation site. Below are the key requirements. Installation Area Minimum space: 2.58 m (length) × 1.5 m (width) × 2.5 m (height). Surface: flat, ...
In which countries must additional steps be taken before using the DMD system?
Before operating the DMD system in the listed countries, you must inform the APSTEC team. In some cases, national frequency authorities may require notification or special authorization. If a regulator needs additional information not supplied with ...
How to properly store the DMD system?
The DMD system must be stored in facilities under the same conditions as described in the article on transportation. Keep the DMD system in a dry place. Do not turn over the boxes containing the system. Boxes from the same system may be stacked, but ...
How to properly assemble the DMD system?
Use the DMD system assembly manual for all installation and disassembly instructions. The DMD system is designed for stationary installation only, at locations approved by the APSTEC technical team. Assembly must be performed only by trained ...
How to Operate the DMD System?
1. System initialization and Operating Modes The user can perform several actions to operate the DMD system: Power On — Turns on the system from a powered-off state. After switching on, the system automatically enters the Initialization phase. ...