MT8931C
The B1 and B2 channels each have a bandwidth of
64 kbit/s and are used to carry PCM voice or data
across the network.
B2
B2
B2
B2
B2
B2
B2
B2
The D-channel is primarily intended to carry
signalling information for circuit switching through the
ISDN network. The SNIC provides the capability of
having a 16 kbit/s or full 64 kbit/s D-channel by
allocating the B1-channel timeslot to the D-channel.
Access to the depacketized D-channel is only
granted through the parallel microprocessor port.
B2
B2
B2
B2
Channel 3 (B2)
B2
B2
B2
B2
The C-channel provides a means for the system to
control and monitor the functionality of the SNIC.
This control/status channel is accessed by the
system through the ST-BUS or microprocessor
port.
The C-channel provides access to two
registers which provide complete control over the
state activation machine, the D-channel priority
mechanism as well as the various maintenance
functions. A detailed description of these registers is
discussed in the microprocessor port interface.
B1
B1
B1
B1
B1
B1
B1
B1
Channel 2 (B1)
B1
B1
B1
B1
Output in high impedance state
B1
B1
Don’t care
B1
B1
C0
C0
Line Code
The line code used on the S-interface is a Pseudo
ternary code with 100% pulse width as seen in
Figure 5 below. Binary zeros are represented as
marks on the line and successive marks will
alternate in polarity.
C1
C2
C2
C1
C5
C6
C6
C5
Channel 1 (C)
C3
C4
C4
C3
C7
D7
D7
C7
BINARY
VALUE
0
1
0
0
0
1
0
0
1
1
Only valid with 64 kbit/s D-channel
D6
D6
LINE
SIGNAL
Violation
D5
D5
Channel 0 (D)
D4
D3
D3
D4
Figure 5 - Alternate Zero Inversion Line Code
A mark which does not adhere to the alternating
polarity is known as a bipolar violation.
D2
D1
D0
DSTo
D0
D1
D2
Figure 4 - ST-BUS Channel Assignment
9-75
F0od
DSTi
F0b
MITEL [ MITEL NETWORKS CORPORATION ]
