ST 40
2
‘CAYMAN’ NLJD
31
Items known to contain semiconductor components (electronic instruments, office and home
equipment, communication devices, etc.) are checked by other means.
When running checks on enclosing structures, it is important to set a suitable receiver gain. If
excessive, it may well cause detection of objects behind the walls, which may be a problem when
there is no access into the adjoining spaces. On the other hand, if the gain is too small, targets of
interest with a weak response may remain undiscovered in the structure under scrutiny.
While scanning walls and other large vertical structures, it is recommendable to move the
antenna from top to bottom in a serpentine fashion, as is shown in Fig. 9.
Fig. 9
The antenna head should be held at a distance of 5-15 cm from the surface.
If a potent response is registered (all LEDs in an multi-segment LED gauge bar light up), the
gain should be decreased in order to establish the exact location of the responding target.
The primary task for an NLJD is the discovery of eavesdropping devices, whose giveaways
are the signals returned by semiconductor-containing electronic components and by MOM-
structures on casings, at junctures, etc. Therefore, particular attention should be paid to scanned
areas where responses have been observed on the red led gauge bar alone, and on both red and
blue multi-segment LED gauge bars. The nature of each such response should be determined and
its source identified.
A strong, off-scale response on one of the multi-segment LED gauge bars may be accompanied
by a much weaker one on another. As a rule, the former is a true response and the latter a false
one; it is advisable to decrease the gain or move away from the target until there is no off-scaling.
Small-sized objects should be checked at locations where no response is observed on any of
the three INPUT LEVEL led gauge bars, preferably away from large metal structures, pillars,
cabinets, safes, etc.
