Nortel Networks 1000 - Manual (Page 147)

Application 147
Termination transmission characteristics
The loss plan for OPS connections is designed so that a connection with
an OPS termination provides satisfactory end-to-end listener volume
when the OPS termination is a standard telephone. The listener volume
at the distant end depends on the OPS termination transmit loudness
characteristics; the volume at the OPS termination end depends on the
OPS termination receive loudness characteristics.
A feature of many (though not all) standard telephones is that the loudness
increases with decreased current. So as the line (PBX to OPS termination)
facility gets longer and loss increases, the increased loudness of the
telephone somewhat compensates for the higher loss, assuming direct
current feed from the PBX with constant voltage at the feeding bridge.
However, this compensation is not available when:
•
the termination is a non-compensating telephone
•
the OPS port is served by a line card using a constant-current feeding
bridge
•
the OPS termination is to telephones behind a local switch providing
local current feed, such as a fax machine or a key telephone system
OPS line terminations with loudness characteristics designed for other
applications can also impact transmission performance. For example,
wireless portables loudness characteristics are selected for connections
to switching systems for wireless communication systems; if used in an
OPS arrangement without consideration for these characteristics, the result
could be a significant deviation from optimum loudness performanceThe
loss plan for OPS connections is designed so that a connection with
an OPS termination provides satisfactory end-to-end listener volume
when the OPS termination is a standard telephone set. The listener
volume at the distant end depends on the OPS termination transmit
loudness characteristics; that at the OPS termination end depends on
the OPS termination receive loudness characteristics. With standard
telephone sets, these characteristics are such that satisfactory—if not
optimum—performance is achievable within the above noted objectives for
connecting facilities.
A feature of many (though not all) standard telephone sets is that the
loudness increases with decreased current. So as the line (Meridian 1 to
OPS termination) facility gets longer and loss increases, the increased
loudness of the set somewhat compensates for the higher loss, assuming
direct current feed from the PBX with constant voltage at the feeding
bridge. However, this compensation is not available when:
Nortel Communication Server 1000
Circuit Card Reference
NN43001-311 02.06 Standard
27 August 2008
Copyright © 2003-2008 Nortel Networks
.