Nortel Networks Circuit Card 311 - Manual (Page 153)

Application 153
When a port is configured for CLS OPS, loss is programmed into the OPS
analog line card on a call-by-call basis. When configured for CLS ONS, an
OPS analog line card port is programmed to a value that is fixed for all calls.
The loss in the other port involved in the call can vary on a call-by-call basis
to achieve the total loss scheduled by the plan.
For satisfactory transmission performance, particularly on connections
between the public network and an OPS termination, it is recommended
that facilities conform to the following:
• Total 1 kHz loss from the local serving CO to the OPS terminal should
not exceed 7.0 dB. The total loss in the facility between the PBX and
the terminal must not exceed 4.5 dB. See
Figure 25 "Traditional OPS
application configuration" (page 149) .
The following requirements are based on historic Inserted Connection
Loss (ICL) objectives:
— PBX – CO trunk: 5 dB with gain; 0 – 4.0 dB without gain
— OPS line: 4.0 dB with gain; 0 – 4.5 dB without gain. In recent times
economic and technological considerations led to modifications of
these historic objectives. But since the loss provisions in the PBX for
OPS are constrained by regulatory requirements as well as industry
standards, they are not designed to compensate for modified ICL
designs in the connecting facilities.
• Nortel recommends that the attenuation distortion (frequency response)
of the OPS facility be within ±3.0 dB over the frequency range from
300 to 3000 Hz. It is desirable that this bandwidth extend from 200
to 3200 Hz.
• The terminating impedance of the facility at the OPS port be
approximately that of 600 ohms cable.
If the OPS line facility loss is greater than 4.5 dB but does not exceed 15
dB, line treatment using a switched-gain Voice Frequency Repeater (VFR)
extends the voice range.
The overall range achievable on an OPS line facility is limited by the
signaling range (2300 ohms loop including telephone resistance). The
signaling range is unaffected by gain treatment;so gain treatment can be
used to extend the voice range to the limit of the signaling range. For
example, on 26 AWG wire, the signaling range of 2300 ohms corresponds
to an untreated metallic loop loss of 15 dB. Gain treatment (such as a VFR)
with 10.5 dB of gain would maintain the OPS service loss objective of 4.5
dB while extending the voice range to the full limit of the signaling range.
Nortel Communication Server 1000
Circuit Card Reference
NN43001-311 01.04 Standard
Release 5.0 23 May 2008
Copyright © 2003-2008, Nortel Networks
.