Nortel Networks DCT1900 - Manual (Page 111)

Technical Product Manual - DCT1900
Configuration Directions, Limitations of the System
Config-DCT1900/R8/mw 2-1
© 2000-2005
C HAPTER 2
Limitations of the System
2.1 Modular Cabinets
Cabinet
A system can support up to 4 cabinets. Each cabinet provides space for a combination of 9
system boards. This means that the total size of the system may be 36 system boards. All boards,
except for the CPU which is always placed in cabinet 1, can in principle be placed in any slot.
However, due to the MCCB layout and power limitations not all combinations are allowed.
Powering limitations of the Modular Cabinet are discussed in paragraph 2.2.
Connection Board
A Modular Cabinet has only one MCCB which is factory fitted. The MCCB provides Base Station
power connections for a total of 7 CLU and/or SLU boards.
Power Supply
Modular Cabinets are powered by an external -48Vdc supply. Base Stations may be powered by
the same power supply or by a second external power supply connected to the MCCB.
Base Stations
The number of Base Stations is limited to 120. A number of Base Stations can be powered via a
single cabinet as mentioned above. Furthermore, the external power source specifications can
limit the maximum number of Base Stations.
Number of Portable Telephones
The number of Portable Telephones that can be supported by the Standalone DCT1900 system is
600 when digital trunks (DTUs) are used, 144 when digital links (DLUs) are used and 208 Portable
Telephones when analog lines (LTUs) are used. The number of Portable Telephones supported by
the DCT1900 Mobility System controlled by the MS but cannot exceed 2048 for a single RE.
CPU Firmware
The memory space reserved by the CPU for each type of board is limited to a maximum of 15 CLU
boards, 8 SPU/SLU, 34 LTU, 10 DTU-E1 , 34 DLU and 13 DTU-T1.
Cabling
When the cable length is only data limited, Base Stations may be connected up to a distance of 2.2
miles away from the REs when using a CLU board, or 1.3 miles when using a SLU/CLU-S board.
In case the cable length is power limited, the distance depends on the powering method that is
used (see Chapter 4).
For the DTU E1 card, in case a cable other than the Ericsson supplied cable is used between the
RE and the PBX to cover a longer distance, this cable should not attenuate more than 6dB at
1.024 MHz (e.g. a cable with an attenuation of 2 dB/100 m at 1.024 MHz gives a maximum
distance of 328 yards). The maximum length of 100 ohm cable used to connect the DTU-T1 to a
PBX/Centrex is 666 ft.
All twisted pair cables are shielded signal cables and the shield must be tied to ground by using
the ground strip at the bottom of the cabinet. This ground strip provides cable connections for any
combination of up to 8 twisted pair shielded cable sets.