Perimeter layout
OmniTrax Product Guide Page 55
Placement of decouplers
Decouplers are installed at the ends of sensor cable sets (see Installing decouplers and
terminators on page 132) to terminate the radio frequency (RF) signals, which form the detection
field. There are two types of decouplers. Network decouplers allow DC power and alarm data to
pass from processor to processor over the cables. Standalone decouplers allow data to pass but
block DC power. Typically, the detection field continues a short distance past the decouplers.
However, different soil composition and cable spacing makes the length of the extended detection
field vary from site to site.
A combination of site-specific factors occasionally results in a high clutter signal at decoupler
locations, especially in SC1 single cable systems and narrow cable spacing applications. To
screen out high clutter and prevent potential detection shadows at decoupler locations, Senstar
recommends that decouplers be overlapped by 4 m (13 ft.) by forming active cable loops. The 4 m
of overlapping detecting cable is defined as non-detecting in software, which prevents the high
clutter and the resulting detection shadows. Install the decouplers side by side and at the same
burial depth as the cables. The transmit cables from two adjacent cable sets are connected using
decouplers and a cable loop, as are the corresponding receive cables (i.e., TXA to TXB and RXA
to RXB).
For OC2 and SC2 cable, the decouplers must be lined up and parallel. The maximum distance
from parallel alignment for OC2/SC2 decouplers is 30 cm (12 in.).
Note Use flags, stakes, or paint to mark the location of the red bands on the
ground’s surface. The red band’s positions are required for sensor
calibration.
Note Bury and seal decouplers according to the procedures for each medium
(see (Installing decouplers and terminators
on page 132). Bury
decouplers at the same depth as the cables. If installing in concrete,
place a metal or fiber-board plate over the slots to protect the
decouplers until the sealant cures.
The active cable loops at decoupler locations DO NOT have to follow
the minimum turn radius for detecting cable. Much tighter turns can be
used providing that the smallest allowable bend radius of 15 cm (6 in.)
is not violated.
Use flags, stakes, or paint to mark the location of the decouplers on the
ground’s surface. The decoupler’s positions are required for sensor
calibration.
Note Maintain the separation between the TXA and TXB, and the RXA and
RXB cables.
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