Nortel Networks Circuit Card 311 User Manual
Page 155
Application
155
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 ohm loop including telephone resistance). 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:
15.0 dB
(loss corresponding to the maximum signaling range)
–
4.5 dB
(OPS service loss objective)
=
10.5 dB
(required gain treatment)
The use of dial long line units to extend the signaling range of OPS analog
line cards beyond 15 dB is not recommended.
Loss is inserted between OPS analog line card ports and other Meridian
1 ports in accordance with the Meridian 1 loss plan. This plan determines
the port-to-port loss for each call. When a port is configured for OPS
class-of-service, loss is programmed into the OPS analog line card on a
call-by-call basis. When configured for ONS class-of-service, an OPS
analog line card port is programmed to a value that is fixed for all calls,
although the loss in the other port involved in the call may 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. Of that total, the loss in the facility between the PBX
and the terminal should not exceed 4.5 dB (see
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 consideration has
led to modifications of these historic objectives. However, the
loss provisions in the PBX for OPS are constrained by regulatory
requirements as well as industry standards; so, they are not designed
to compensate for modified ICL designs in the connecting facilities.
Nortel Communication Server 1000
Circuit Card Reference
NN43001-311
01.04
Standard
Release 5.0
23 May 2008
Copyright © 2003-2008, Nortel Networks
.