Nortel Networks 1000 - Manual (Page 146)

146 NT1R20 Off-Premise Station Analog Line card
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 90
"NTCK80AA/AB/AC/AD" (page 332) . 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 Economic and
technological changes led to modifications of these 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 Networks 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 set 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.
15 dB
–4.5 dB
= 10.5
dB
The use of dial long line units to extend signaling range of OPS analog line
cards beyond 15 dB is not recommended.
Nortel Communication Server 1000
Circuit Card Reference
NN43001-311 02.06 Standard
27 August 2008
Copyright © 2003-2008 Nortel Networks
.