Nortel Networks Circuit Card - Manual (Page 633)

NT8D15 E&M Trunk card Page 633 of 906
Circuit Card Description and Installation
Card interfaces
The E&M trunk card passes voice and signaling data over DS-30X loops and
maintenance data over the card LAN link.
The E&M trunk card contains four identical and independently configurable
trunk interface units (also referred to as circuits). Each unit provides
impedance matching and a balance 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. A
CODEC performs A/D and D/A conversion of trunk analog voiceband
signals to digital PCM signals.
The four units on the card can operate in the A-Law or the µ-Law companding
mode. The mode is selected by making service change entries. Each unit can
be independently configured for 2-wire E&M, 4-wire E&M, and paging trunk
types. The trunk type is selected by service change entries and jumper strap
settings. All units on the card can perform the following features:
• convert transmission signals from analog-to-digital and digital-to-analog
• provide outpulsing on the card: make/break ratios are defined in software
and downloaded at power-up and by software command
• provide 600-ohms balance and termination impedance (2-wire
configuration)
• provide 600-ohms termination impedance (4-wire configuration)
• provide pad control for 2-wire and 4-wire facility connections
• enable trunk type and function to be configured on a per-port basis in
software
• provide isolation of foreign potentials from transmission and signaling
circuit
• provide software control of A-Law and µ-Law modes
• support loopback of pulse code modulation (PCM) signals to DS-30X for
diagnostic purposes