Nortel Networks Circuit Card 311 - Manual (Page 158)

158 NT1R20 Off-Premise Station Analog Line card
• 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:
• the termination is a non-compensating telephone set
• the OPS port is served by a line card using a constant-current feeding
bridge
• the OPS termination is to telephone sets behind a local switch providing
local current feed, such as a key telephone system
OPS line terminations with loudness characteristics designed for other
applications may also impact transmission performance. For example,
wireless portables loudness characteristics are selected for connections to
switching systems for wireless communication systems; if deployed in an
OPS arrangement without due consideration for these characteristics, the
result could be a significant deviation from optimum loudness performance.
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.
Nortel Communication Server 1000
Circuit Card Reference
NN43001-311 01.04 Standard
Release 5.0 23 May 2008
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