Nortel Networks DCT1900 - Manual (Page 248)

Technical Product Manual - DCT1900
Installation Instructions, Synchronization Distribution Board (SDB) – REX-BRD0006 or ROANB 101 38
18-2 Install-DCT1900/R8/mw
© 2000-2005
Fig. 18–2 Electrical Schematic Diagram
18.2 Installation
The SDB comes as part of the installation set sync port kit (NTMNB 101 107) and must be installed
in the cabinet where the CPU1 is going to reside (refer to Paragraph 4.7 of Chapter 4). For the
installation of the cables to the CPU1 refer to Chapter 19, CPU1 Cabling. The external sync in and
out cables are part of the sync port kit and are required if PWT air interface synchronization is
needed in a multi DCT1900 system environment. They must meet the requirements in Paragraph
18.3 (see Figure 18-3).
18.3 External Sync Cable
When there are multiple DCT1900 systems with overlapping coverage areas it is necessary to
synchronize the CPUs of the systems together. This is done by connecting an external sync cable
from one of the sync out ports on the master CPU’s sync board to the sync in port on one of the
slave CPU’s sync board.
A pre-made external sync cable, TSR 951 284, is available. The specifications for this cable are
included below. If this cable is not long enough then a cable must be constructed on site. Refer to
the enclosed specifications to construct this cable. If the 6 conductor shielded flat cable is not
available then a single pair of 120 ohm twisted shielded pair may be used.
The signal delay in the external sync cable must be determined. For the cable TSR 951 284 it is
0.04
μs. A cable made on site must be measured using a TDR (Refer to Paragraph 18.4).
Once the delay is known, this value is entered into the slave system’s CPU during its’ initialization.
Refer to the Cordless System Software User’s Guide (LZB 119 2664), Appendix I, on how to enter
this delay.
1 2 3 4 5 6 1 2 3 4 5 6 1 2 3 4 5 6 1 2 3 4 5 6
1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4
X5 X6 X7 X8
X1 X2 X3 X4
CIRCUIT GND
CIRCUIT GND
GND(shield) GND(shield) GND(shield) GND(shield)
SYNC OUT SYNC OUT SYNC OUT SYNC IN
A B A B A B A
'
B
'
To CPU ---------------------------------------------------------
To other
CPU RJ Connectors