NT8D14 Universal Trunk card Page 571 of 906
Circuit Card Description and Installation
Card interfaces
The NT8D14 Universal Trunk card passes voice and signaling data over
DS-30X loops, and maintenance data over the card LAN link. These
interfaces are described in “Intelligent Peripheral Equipment” on page32 .
Trunk interface units
The NT8D14 Universal Trunk card contains eight identical and
independently configurable trunk interface units (also referred to as circuits).
Each unit provides impedance matching and a balanced network in a signal
transformer/analog hybrid circuit.
Also provided are relays for placing outgoing call signaling onto the trunk.
Signal detection circuits monitor incoming call signaling. Two codecs are
provided for performing A/D and D/A conversion of trunk analog voiceband
signals to digital PCM signals. Each codec supports four trunk interface units.
The following features are common to all units on the card:
• trunk type configurable on a per unit basis
• terminating impedance (600 or 900 ohms) selectable on a per-unit basis
(minimum vintage BA)
• balance impedance (600 or 900 ohms or complex impedance network)
selectable on a per-unit basis (minimum vintage BA)
• control signals provided for RAN and paging equipment
• loopback of PCM signals received from trunk facility over DS-30X
network loop for diagnostic purposes
• switchable pads for transmission loss control