Nortel Networks 1000 - Manual (Page 145)

Application 145
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.
•
The attenuation distortion (frequency response) of the OPS facility
should 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 should
approximate that of 600 ohm 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 ohm loop including telephone set 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 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 signaling range of OPS analog line
cards beyond 15 dB is not recommended.
Loss is inserted between OPS analog line card ports and other ports in
accordance with the loss plan. This plan determines the port-to-port loss
for each call. 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.
Nortel Communication Server 1000
Circuit Card Reference
NN43001-311 02.06 Standard
27 August 2008
Copyright © 2003-2008 Nortel Networks
.