![](http://datasheet.mmic.net.cn/350000/CS62180_datasheet_16545897/CS62180_46.png)
during the 6
th
and 12
th
frames. The original LSB
of the channel is actually replaced with the sig-
naling data, hence this is known as "robbed-bit"
signaling. The 6
th
and 12
th
frames can be treated
as one, 2-state channel, allowing a 2-state signal
to be updated twice every superframe. The two
frames can also be treated as separate channels
(A and B), yielding up to 4 separate codes for
each channel every superframe. For voice grade
applications, these signaling bits offer no notice-
able degradation in the signal quality. When
error-free data transmission is required however,
robbed bit signaling can be disabled (transparent
mode), and some other signaling facility must be
provided by the host system.
193E Framing Format
The 193E or Extended Superframe Format al-
lows much greater flexibility in both the use of
the framing bits, and the number of signaling
channels provided. As shown in Figure A6, the
framing bits are divided into 3 channels. The
FPS, or Framing Pattern Sequence, provides a
synchronization signal for determining frame and
superframe alignment. The FDL, or 4 kHz Facil-
ity Data Link, provides a dedicated channel for
system messages. The CRC (Cyclic Redundancy
Check) channel allows CRC check sums to be
transmitted with each superframe to monitor line
quality. As with the 193S format, every 6th
frame is designated as a signaling frame. The 4
signaling frames (6, 12, 18, and 24) can be mul-
tiplexed in different configurations to provide 2,
4, or 16-state signaling codes.
SLC-96
Framing Format
The SLC-96
T1 format is used between the Lo-
cal Digital Switch (LDS) and a SLC-96
Remote Terminal (RT). The framing format is a
SF(D4
) superframe format with specialized
Data Link (DL) information bits. The DL bits
consist of Concentrator (C), Spoiler (S), Mainte-
nance (M), Alarm (A) and Protection Line
Switch (PLS) bits as shown in Figure A7.
T1DM Framing Format
The T1DM T1 format is used for DDS
service
among hub and local intermediate DDS
offices.
As shown in Figure A8, the framing format is a
SF(D4
) superframe format with a specialized
channel 24 structure. The T1DM accepts up to
23 DS-0 signals and inserts one seven-bit byte
from each signal into the first twenty-three 8-bit
channel slots of the DS1 frame. The 24th chan-
nel slot contains a special synchronizing byte as
shown in Figure A9. DDS
equipment insures
that every DS0 channel contains at least one "1".
Therefore, neither B8ZS nor bit-7 zero substitu-
tion should be selcted in the CS62180B.
193E
Frame
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
F-bits
FPS FDL CRC
m
Channel
bits
Data
Signaling
Signaling
Options
T
2
4
16
1-8
C1
m
0
m
C2
1-7
Bit 8
-
A
A
A
m
1-8
0
m
C3
m
1
1-7
Bit 8
-
A
B
B
m
1-8
C4
m
0
m
C5
1-7
Bit 8
-
A
A
C
m
1-8
1
m
C6
m
1
1-7
Bit 8
-
A
B
D
Figure A6. 193E Framing Format
CS62180B
46
DS225PP
2