MT8930CPR Zarlink Semiconductor, Inc., MT8930CPR Datasheet - Page 8

• Manufacturer Part Number: MT8930CPR
• Description: 4 Wire Full-duplex 2B+D (192 Kbps) Data Format ISDN S and T Subscriber Network Interface Circuit with Controllerless Mode
• Manufacturer: Zarlink Semiconductor, Inc.

MT8930C
Line Code
The line code used on the S-interface is a Pseudo
ternary code with 100% pulse width as seen in
Figure 6 below.
marks on the line and successive marks will
alternate in polarity.
A mark which does not adhere to the alternating
polarity is known as a bipolar violation.
Framing
The valid frame structure transmitted by the NT and
TE contains the following (refer Fig. 5):
NT to TE:
TE to NT:
The framing mechanism on the S-interface makes
use of line code violations to identify frame
boundaries. The
line code sequence to allow for quick identification of
the
alignment,
balancing bit (L) will also produce a line code
violation. If the data following the balancing bit is all
binary ones, the zero in the auxiliary framing bit (Fa)
or N-bit (for the direction NT to TE) will provide
successive violations to ensure that the 14 bit
9-40
Figure 6 - Alternate Zero Inversion Line Code
BINARY
LINE
SIGNAL
VALUE
- Framing bit (F)
- B1 and B2 channels (B1,B2)
- DC balancing bits (L)
- D-channel bits (D0, D1)
- Auxiliary framing and N bit (Fa, N), N=Fa
- Activation bit (A)
- D-echo channel bits (E)
- Multiframing bit (M)
- S-channel bit
- Framing bit (F)
- B1 and B2 channels (B1, B2)
- DC balancing bits (L)
- D-channel bits (D0, D1)
- Auxiliary framing bit (Fa) or Q-channel bit
frame
the
boundaries. To
0
1
next
F-bit
Binary zeros are represented as
0
0
mark
violates
0
1
secure
following the frame
0
Violation
the
0
the
1
alternating
1
frame
criterion (13 bit criterion in the direction TE to NT)
specified in Recommendations I.430 and T1.605 is
satisfied. If the B1-channel is not all binary ones, the
first zero following the L-bit will violate the line code
sequence, thus allowing subsequent marks to
alternate without bipolar violations.
The Fa and N bits can also be used to identify a
multiframe structure (when this is done, the 14 bit
criterion may not be met). This multiframe structure
will make provisions for a low speed signalling
channel to be used in the TE to NT direction
(Q-channel). It will consist of a five frame multiframe
which can be identified by the binary inversion of the
Fa and N-bit on the first frame and consequently on
every fifth frame of the multiframe. Upon detection of
the multiframe signal, the TE will replace the next Fa-
bit to be transmitted with the Q-bit.
The DC balancing bits (L) are used to remove any
DC content from the line. The balancing bit will be a
mark if the number of preceding marks up to the
previous balancing bit is odd.
marks is even, the L-bit will be a space.
The A-bit is used by the NT during line activation
procedures (refer to state activation diagrams). The
state of the A-bit will advise the TE if the NT has
achieved synchronization.
The E-bit is the D-echo channel. The NT will reflect
the binary value of the received D-channel into the
E-bits.
contention
configuration. This is described in more detail in the
section of the D-channel priority mechanism.
The M-bit is a second level of multiframing which is
used for structuring the Q-bits. The frame with M-
bit=1 identifies frame #1 in the twenty frame
multiframe.
shown in Table 1.
multiframes must be performed externally.
Bit Order
When using the B-channels for PCM voice, the first
bit to be transmitted on the S-Bus should be the sign
bit.
standards which transmit PCM voice as most
significant bit first. However, if the B-channels are to
FRAME #
This complies with the existing telecom
11
16
This is used to establish the access
1
6
Table 1. Q-channel Allocation
resolution
The Q-channel is then received as
All synchronization with the
in
Q-Bit
Q2
Q3
Q4
Q1
a
point-to-multipoint
If the number of
M-Bit
0
0
0
1