Preliminary Information
MH89760B
T1 Interface
Switch Matrix
MT8980
Digital Line Interface
MH89760B
MT8910
STo1
STi0
DSTi
OUTA
DSTo
DSTi
•
•
Equal-
izer
DSTo
STi1
STo2
STi3
STo0
•
•
Z
T
OUTB
RxR
CSTi0
CSTo
C4i
F0i
STo3
CSTi1
RxT
•
•
•
•
•
•
•
•
•
•
•
•
•
•
C2i
F0i
µP
E8Ko
C1.5i
D-Channel Processing
MT8952
MT8952
DSTo
MT8941
MT8910
DSTo
DSTi
DSTi
•
•
DSTo
DSTi
•
F0i
C1.5
Z
T
•
•
•
•
µP
µP
F0o
•
C2o
C4o
MT8952
E8Ko
DSTo
DSTi
µP
Figure 14 - ISDN Voice Data Channel Bank
5. Digital Access Cross Connect System
(DACS)
To control and monitor the MT8910s and the T1
interface the switch matrix operates some of its input
and output streams in message mode. This enables
the system to control all of the functions of the
MT8910s and the T1 interface through the Control
ST-BUS points, (CSTi/o).
The Digital Access Cross Connect System (DACS) is
a T1 switch with 127 T1 lines as input and output
plus one T1 line that is reserved for test and
maintenance purposes. A DACS is capable of
switching any input channel on any T1 trunk to any
output channel on any T1 trunk.
Clock synchronization is done by the MT8941.
Phase-locked loop # 2 generates ST-BUS clocks that
are synchronized to the extracted 8kHz output from
the T1 interface. Phase-locked loop #1 generates
the transmit T1 clock synchronized to the ST-BUS
clocks, which are synchronized to the extracted T1
clock. This scheme will also allow the system to
operate in a loop timed mode.
There are four main blocks in Figure 15, the T1
interfaces, the switch matrix, the control matrix, and
the clock generator. The digital trunk interface is
made up of the MH89760B plus the additional
components required to interface to the transmission
line. The MH89760B handles all of the required
transmit and receive data formatting, and converts
the 1.544 MHz serial stream into ST-BUS format so
that it can be routed through the MT8980
synchronous switch matrix.
With appropriate multiplexing a single D channel
processor can handle all 23 2B+D interfaces. If both
B channels on all 24 lines are going to be used then
it would be necessary to use two T1 trunk interfaces.
4-75
MITEL [ MITEL NETWORKS CORPORATION ]
