Metor 6M - Page 7

Metor 6M PAGE 5
Installation and Operating Manual
92102916 REV 5 1. PREFACE
Operating frequency - The frequency of the electromagnetic field generated by a
WTMD. Usually WTMDs have several different operating frequencies. When
calibrating a WTMD at the installation site the operating frequency with lowest
interference level is chosen. Several operating frequencies enable also side-by-side
use of multiple WTMD without synchronization cables.
Detection uniformity - The ability of a WTMD to maintain uniform sensitivity
throughout the whole detection area regardless of the shape and orientation of the
metal item. Detection uniformity directly affects the discrimination capability of a
WTMD. The sensitivity of a WTMD is usually set according to the weakest
position of the detection area. In case of poor detection uniformity this may lead to
unnecessary high sensitivity in other parts of the passage, considerably degrading
discrimination. When the detection uniformity of a WTMD is tested it should
always be done with real objects e.g. a weapon, or their simulators. Cylinders or
spheres as test items can give wrong indications on the true detection uniformity of
a WTMD.
Interference immunity - The operation of a WTMD can be affected by electrical
or mechanical interferences. Electrical interferences are caused by other electrical
equipment which are usually located near the installation site. Electrical
interferences can be conducted through the mains power line or radiated.
Mechanical interferences are caused by e.g. moving metal items near the WTMD
or vibrating behind wall or underneath floor constructions. Good interference
immunity can only be achieved through effective hardware and software filtering
as well as specialized coil design.
Critical test object - The most difficult object to be detected from a group of test
objects. Requires the highest sensitivity for detection.