Nortel Networks 1000 - Manual (Page 462)

462 NT8D09 Analog Message Waiting Line card
Line interface units
The analog message waiting line card contains 16 identical and
independently configurable line interface units (also referred to as circuits).
Each unit provides 600-ohm impedance matching and a balance network
in a signal transformer/analog hybrid circuit. Circuits are also provided
in each unit to apply the ringing voltage onto the line synchronized
to the ringing current zero crossing. Signal detection circuits monitor
on-hook/off-hook status and switchhook flash detection. Four CODECs
are provided to perform A/D and D/A conversion of line analog voiceband
signals to digital PCM signals. Each CODEC supports four line interface
units. The following features are common to all units on the card:
•
transmission and reception of Scan and Signaling Device (SSD)
signaling messages over a DS30X signaling channel in A10 format
• loopback of SSD messages and pulse code modulation (PCM) signals
for diagnostic purposes
• correct initialization of all features, as configured in software, at
power-up
• direct reporting of digits dialed (500 telephones) by collecting dial
pulses
• connection of –150 V dc at 1 Hz to activate message waiting lamps
in two telephones in parallel. The two telephones must be the same
type or the neon series resistor in each telephone must be 54 K ohms
or greater.
• lamp status detection (does not detect a failure of either lamp when
operating in parallel)
•
disabling and enabling of selected units for maintenance
•
40 mA to telephones with short circuit protection
Card control functions
Control functions are provided by the following:
•
a microcontroller
•
a card LAN interface
• signaling and control circuits on the analog message waiting line card
Microcontroller
The analog message waiting 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 CE CP through the card LAN link:
Nortel Communication Server 1000
Circuit Card Reference
NN43001-311 02.06 Standard
27 August 2008
Copyright © 2003-2008 Nortel Networks
.