Tadiran Telecom Coral IPx 500X, Installation Procedure And Hardware Reference Manual, Page: 388 / 400

8-20
Coral IPx 800 Installation Manual
HDC C
a
rd
Hig
h
Den
sity Con
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o
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8
The HDC card (in combination with one PX card when two expansion cages IPx 800X
are installed, see
Figure 8-1
) is functionally similar to the 4GC/32GC card used in
larger capacity Coral systems. The HDC card supports two HDLC and eight PCM
highways (each PCM highway provides 64 time slot,) and drives the peripheral buses
directly.
Figure 8-2
illustrates the four major circuit areas of the HDC card in a block diagram.
Figure 8-2 HDC Circuit
Block Diagram
Clock Selection
The external clock selector monitors the two inputs for the presence of an 8.0 kHz
clock signal that can be obtained from the incoming data stream of a digital trunk
card. A primary and secondary clock source may be defined in the system database to
synchronize the PCM clock of the HDC card with the digital trunk. If there is no
external clock source, the HDC card always reverts to an internal clock.
The HDC card contains phase-lock circuitry that synchronizes the Coral PCM clock to
a signal derived from one of two digital trunk interface cards (PRI23, PRI30, 4TBR,
8TBR, 30T, 30T/x or T1), designated the primary and secondary external clock source.
This feature, called “slaved clock” or “loop-timed” operation, enables the Coral system
to integrate with any digital telephone network in the world. The HDC monitors
external clock signal integrity and switches the system between the primary and
secondary external clock sources, or internal HDC clock, as necessary.
2 Circuit Description
Digital Tone Generation
CPU
Universal I/O Slots
Clock & Sync Generation
External Clock Selector
Primary
Sync Secondary
Sync
HDLC
PCM
HDLC Tx
PCM Tx
HDLC Rx
PCM Rx
Timeslots
0 - 511
Clock (4.096 MHz)
Sync (8 KHz)
Clk Select
RAM
Card
Software
PROM
U56
Local
Bus
Data
Time Slot Management
512 x 512