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Panasonic Digital Business System - Overview
April 1997
Cabling Requirement
The cabling between the Central Control Unit (CCU) and each extension is 2 wire, 0.5mm
diameter copper conductor and terminated with a Line Jack Unit (LJU). Use a master LJU for
analogue extensions and a slave LJU for the digital extensions.
The following table shows the maximum cable length from the CCU.
Cabling from the Network Test and Termination Point (NTTP) must also comply with these
requirements.
Cable
CCU > ITS
CCU > DSS
CCU > 1AS (A version)
CCU > 1AS (B version)
CCU > PFU
NTTP > CCU
Over-voltage Protection
Surge arresters are fitted to the PAS, ITS and 1AS ports of the system. If the extension
cabling extends between buildings or runs around the outside of a building, surge arresters
should be fitted at both exit and entry points.
PBX Recall
The DBS can be installed as a host or subsidiary system to suitably approved PBX
equipment.
As a host the DBS will accept timed break recall signals from a PBX connected to a 1AS
port.
As a subsidiary the DBS can provide both timed break and earth recall signalling to the host
from PAS ports.
1AS Port Line Feeding
The DBS is not a through fed system. Line feeding from 1AS ports to connected equipment is
derived internally from the DBS CCU. The maximum current that can be supplied to
extension equipment on 1AS ports is 50mA.
Analogue Extensions
When using separately approved extension apparatus, Panasonic recommend DTMF
signalling. The recall signalling must be timed break. The impedance class of the apparatus
must be class (a) of clause 4.3.2.1 of BS6305:1982.
Maximum Loop Resistance
40 ohms
20 ohms
100 ohms
100 ohms
Table 7 - Maximum Cable Distances
6
Issue 6
Maximum Length
240m
120m
480m
880m
250m
15m
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