Nortel Enterprise 1000 Reference Manual page 224

Page 224 of 236
553-3023-211 Standard 1.00 June 2001
Analog line cards
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 52.
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 have 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) will
extend 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; thus, 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