Nortel DMS-100 Series General Description Manual page 72

3-4 Ringing in Series II peripherals
RCU components associated with ringing
A detailed functional description of the circuit cards in the RCU is in DMS-1
Urban Circuit Pack Descriptions. A very brief description of the RCU
components associated with ringing is in the following table.
Table 3-3 RCU ringing hardware component description
Component
NT3A68
NT3A31
NT3A42
NT3A39
LCC
Ringing generator capacity
The RCU ringing generator is capable of ringing up to 50 lines simultaneously.
The number of lines that can be rung during one ringing cycle depends on the
ringing type used. Since the SCM-100U schedules ringing during all three
phases of the ringing cycle, it is possible to ring up to 150 lines, or 50 lines per
phase, during one cycle for single-party ringing. Again, this depends on the
ringing type.
Ringing generator takeover/take back
The RCU has duplicated ringing generators. One ringing generator is active,
while the mate is standby. A monitor and alarm circuit in the ringing generator
monitors the ringing generator output, controls ringing generator switchover
relays, shuts down the faulty ringing generator, and reports a ringing generator
alarm.
297-1001-131 Standard 06.01 October 2000
Description
DS-1 interface. The DS-1 interface card converts the serial
data from the DS-1 links to parallel data for use by the RCU
controller.
Control processor. The control processor controls the
functions of the RCU and responds to commands from the
SCM-100U. The RCU control processor performs line
supervision, common equipment audits, and backup
equipment switchover independently of the SCM-100U.
Under direction of the SCM-100U, the control processor
performs channel assignments and takedowns, signaling,
and maintenance functions.
Timing. The timing card provides timing for RCU and buffers
the control and monitoring messages between the control
processor and other cards in its shelf.
Ringing generator. The ringing generators provide a 20 Hz
ringing signal superimposed on +/-48 V.
Line card controller. The line card controller interfaces four
line cards at the RCU with the common equipment in the
RCU. The line card controller transfers PCM samples and
control information, handles signaling, receives ringing
samples, and performs maintenance functions on its
associated line cards.