Technical Manual

Technical Manual AM Systems
General AM and EAS issues v4.4 Page 9 of 72
3 General AM and EAS issues
This chapter covers the various issues related to Acoustic Magnetic systems and
Electronic Article Surveillance systems in general, like:
x Noise sources
x Installation guidelines
3.1 Noise sources
Listed below are various noise sources that might affect the performance of any EAS
system. It is strongly advised to either eliminate these noise sources (as far as possible)
or maintain the largest possible distance to these noise sources.
The following devices can create or absorb AM noise signals which can reduce the
performance of an EAS system:
x AM systems installed in other shops (even if they are installed up to 100m or
more away from your store).
x Any electronic device that operates around 58kHz or produces harmonic
frequencies around 58kHz.
x An active laptop. The back light in the screen can create a lot of noise which is
detected by the EAS system and can reduce the performance dramatically. Make
sure to keep laptop computers at least 3 meters away from the antennas.
x (Moving) Objects containing metal, like sliding and revolving doors, elevators,
escalators, roller shutters, frames, etc.
x Electronic devices, like computers, laptop screens, LCD screens, cash registers,
engines, transformers, etc.
x Vertically positioned power cables, both low voltage and high voltage.
x Lights (flashing, fluorescent, halogen, gas-de-charge, etc.)
x Metal scan systems installed in close vicinity. Cross Point’s Metal Scan operates
around 19kHz in channel 0 and has a second harmonic frequency around 58kHz.
3.2 Installation guidelines
Listed below are EAS installation guidelines to ensure a proper installed and functioning
system. Not following these guidelines might result in less performance of the EAS
system.
1. Check the shop entrance/exit carefully for possible noise sources prior to
installation. If possible noise sources are found then try to eliminate these
sources or pick the best position for the EAS system where the influence of
these noise sources will be minimized.
2. If possible, connect a TRX or a set of antennas (1 TRX and 1 RX) and put them
in the required position in the entrance/exit without drilling holes in the floor and
bolting the antennas down. Switch the system on and test the performance. In
this way the noise level and system sensitivity can be determined and if
necessary (in case of high noise or poor sensitivity) the system can be moved to
find a better position.
3. Always install the TRX antenna on that side where the highest noise is or where
the highest noise can be expected.