Nortel Networks 553-3001-211 manual NT8D15 E&M Trunk card Page 621

NT8D15 E&M Trunk card Page 621 of 894

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

Circuit Card Description and Installation