Nortel Networks 553-3001-211 Card control functions, Line interface units, Signaling and control

Page 160 of 894 NT1R20 Off-Premise Station Analog Line card

Line interface units

The NT1R20 OPS analog line card contains eight independently configurable interface units. Relays are 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 Analog/Digital (A/D) and Digital/Analog (D/A) conversion of analog voiceband signals to digital PCM signals.

Each codec supports four 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 service configurable on a per unit basis

•terminating impedance (600 or 900 ohms) selectable on a per unit basis

•standard or complex balance impedance (600 or 900 ohms, 3COM1 or 3COM2) selectable on a per unit basis

•loopback of PCM signals over DS-30X network loop for diagnostic purposes

Signaling and control

This portion of the card provides circuits that establish, supervise, and take down call connections. These circuits work with the CPU to operate line interface circuits during calls. The circuits receive outgoing call signaling messages from the CPU and return incoming call status information over the DS-30X network loop.

Card control functions

Control functions are provided by a microcontroller, a card LAN interface, and signaling and control circuits on the NT1R20 OPS analog line card.

Microcontroller

The NT1R20 OPS analog line card contains a microcontroller that controls the internal operation of the card and the serial card LAN link to the controller card. The microcontroller controls the following:

•reporting to the CPU through the card LAN link:

— card identification (card type, vintage, and serial number)

553-3001-211 Standard 2.00 September 2004