Nortel Passport 15000, Установка и обслуживание оборудования, Страница: 388 / 874

388 Chapter 17 Hardware procedures
241-1501-240 5.2S2
Installing a BITS cable
Install a BITS cable from the timing source directly to the alarm/BITS
module or to a prefabricated cable assembly to enable network
synchronization with the node.
Prerequisites
• You must be familiar with “Safety considerations and best practices”
(page 53).
• The prefabricated alarm/BITS timing cables that you can connect to
include:
— NTHR75
— NTHW75
— NTPN81
• When your timing connection requires a cable that connects directly to
the alarm/BITS module or connects to one of the prefabricated timing
cable assemblies, you need a custom-made BITS cable. See “Making a
BITS cable” (page 635).
• The BITS wire pairs from the site’s B reference timing source plug into
the J3 receptacle and the A reference timing source plug into the J4
receptacle. J3 and J4 are located on the alarm/BITS module at the rear of
the NEBS 2000 frame. The alarm/BITS module receptacle connects to a
male 9-pin D-sub (DB9) connector directly from a site source or as part
of the prefabricated cable assemblies. For a redundant timing setup
(using both the A and the B timing references), a DB9 connector is
needed for each reference at J3 and J4.
Procedure steps
1 Test the signal strength of the site source at the end of the cable before
connecting it to J 3 and J4 of the alarm/BITS module. The signal strength
must be within the range indicated in “Making a BITS cable” (page 635).
If the signal is not within the range, fix the problem between the point of
test and the site source. Depending on the length of cable from the site
source, you many need a thicker gauge cable to ensure the signal
strength.