mh89760b Mitel, mh89760b Datasheet - Page 19

• Manufacturer Part Number: mh89760b
• Description: St-bus? Family T1/esf Framer & Interface
• Manufacturer: Mitel

Preliminary Information
the signalling and link control bus to the MH89760B
status and control channels. All signalling and link
functions may be controlled easily through the STPA
transmit RAM’s Tx0, Tx1, while status information is
read at receive RAM Rx0. In addition, interrupts can
be set up to notify the system in case of slips, loss of
sync, alarms, violations, etc.
3. PCM/Voice Channel Bank
The D3/D4 channel bank is one of the most widely
used pieces of equipment in the North American
network today. The D3/D4 channel converts 24
analog telephone lines into the 24 channels of a T1
serial stream. The channel bank is the interface point
between a digital switching or transmission system
and the analog telephone loop. The industry is
moving towards end-to-end digital
(ISDN), but the analog channel bank will still be in
use for many years to come.
Telecom Bus
Signalling and
High Speed
Link Control
Parallel
BUS
D
R/W
OE
D
A
CS
DS
R/W
DTACK
IRQ
IACK
A
CS
MMS MS1 24/32
0
0
0
0
-D
-A
-A
-D
MT8920B
(Mode 1)
MT8920B
5
(Mode 2)
7
5
7
MMS
+5V
+5V
Figure 12 - Using the MH89760B in a Parallel Bus Environment
STo0
STo1
STo0
STo1
STi0
STi0
C4i
F0i
C4i
F0i
•
•
•
connections
DSTi
DSTo
CSTi0
CSTo
CSTi1
F0i
C2i
C1.5i
E1.5i
MT8976
Extractor
Clock
MH89760B
Figure 13 shows a block diagram of a channel bank
that has been divided into four sections, the analog
line interface, signalling interface, switch matrix, and
T1 interface. The subscriber line interface circuit
(SLIC) provides interface to the telephone line, i.e.,
provides loop current and ringing voltage, and
converts the analog voice signal into µ-Law PCM.
The SLIC also detects the off-hook condition for
conventional POTS (Plain Old Telephone Set)
signalling.
Once the voice is encoded into digital format the
switch matrix transfers the 24 consecutive channels
that are received from the SLICs to the 24 valid
channels used by the MH89760B. The MH89760B
formats and transmits this information on the T1 line.
Signalling information from the telephone sets can
be routed straight through to the output T1 channel,
or it can be routed to the DTMF receiver pool. This is
E8Ko
RxD
RxA
RxB
TxA
TxB
•
•
•
1.544 MHz
Driver
Driver
Line
Line
•
Tx
Rx
F0b
C4b
C8Kb
CVb
F0i
C2o
OUTA
OUTB
RxR
RxT
MT8941
MH89760B
MH89761
Switch
16.384 MHz
12.352 MHz
EQU
DIP
Osc.
Osc.
4-73