Nortel NT1R20, Description

Page: 81 / 316

NT1R20 Off-Premise Station Analog Line Card Page 57 of 290
Line cards Description
Card interfaces
The OPS analog line card passes voice and signaling data over DS-30X loops
and maintenance data over the card LAN link. These interfaces are discussed
in detail in “Intelligent peripheral equipment line cards” on page 8.
Line interface units
The OPS analog line card contains eight identical and independently
configurable line interface units (also referred to as circuits). Each unit
provides impedance matching and a balance network in a signal
transformer/analog hybrid circuit. Relays are also provided in each unit to
apply ringing onto the line. Signal detection circuits monitor
on-hook/off-hook signaling. Two codecs are provided for performing A/D
and D/A conversion of line analog voiceband signals to digital PCM signals.
Each codec supports four line interface units and contains switchable pads for
control of transmission loss on a per unit basis. The following features are
common to all units on the card:
— OPS or ONS (on-premise station) service configurable on a per unit basis
— terminating impedance (600 or 900 ohm) selectable on a per unit basis
— standard or complex balance impedance (600 or 900 ohm or 3COM or
3CM2) selectable on a per unit basis
— loopback of PCM signals over DS-30X network loop for diagnostic
purposes