Nortel Networks 553-3001-211 manual Functional description, Common features

NT8D15 E&M Trunk card Page 619 of 894

Functional description

The NT8D15 E&M Trunk card serves various transmission requirements. The trunk circuits on the card can operate in either A-Law or µ-Law companding modes. The mode of operation is set by service change entries.

Figure 140 on page 620 shows a block diagram of the major functions contained on the E&M trunk card. Each of these functions is discussed on the following pages.

Common features

The following features are common to all circuits on the NT8D15 E&M

Trunk card:

•Analog-to-digital and digital-to-analog conversion of transmission signals.

•Interfaces each of the four PCM signals to one DS30X timeslot in A10 format.

•Transmit and receive SSD signaling messages over a DS30X signaling channel in A10 format.

•Ability to enable and disable individual ports or the entire card under software control.

•Provides outpulsing on the card. Make break ratios are defined in software and down loaded at power up and by software commands.

•Provides indication of card status from self-test diagnostics on faceplate Light Emitting Diode (LED).

•Supports loopback of PCM signals to DS30X for diagnostic purposes.

•Card ID provided for auto configuration and determining serial number and firmware level of card.

•Software controlled terminating impedance (600, 900, or 1200 ohm) two and four-wire modes.

•Allows trunk type to be configured on a per port basis in software.

•Software controlled 600 ohm balance impedance is provided.

•Isolation of foreign potentials from transmission and signaling circuit.

Circuit Card Description and Installation