Toshiba Perfecptione Installation And Maintenance Manual page 342

PERCEPTIONea,,
Tl/DS-1
SEPTEMBER 1991
frames within the Super-frame.
l
The identification is done by verifying the
Terminal Framing (FT) bit sequence
"101010" (odd frames) and the Signaling
Framing (FS) bit sequence "001110" (even
frames). (See Figure 2.)
2) Twenty-four frames per Super-frame. This
grouping is known as the Extended Super-
frame (ESF).
l
In this arrangement the framing bit is time
multiplexed to support three functions,
namely, Synchronization, Cyclic Redun-
dancy Check (CRC), and Facility Data Link
(FDL).
Signaling Protocol: The DS-1 interface is com-
patible with two types of signaling protocol:
cant bit of each time slot in every sixth frame
(sixth and twelfth) is robbed for signaling pur-
poses. The signaling in ESF is closely similar
to the one in SF, but the former contains the A,
B, C, and D signal bits which occur in the sixth,
twelfth, eighteenth, and twenty-fourth frames.
To provide compatibility between SF and ESF
framing format, the A, B, C, and D bits are
used in a manner that C = A and D = B.
2) Common Channel Signaling: The Common
Channel Signaling is also called the Bit Ori-
ented Signaling (BOS). This type of signaling
is mainly used in Digital Multiplexed Interface
(DMI) applications. In this protocol, the first 23
bits are used for data processing, while the
last bit is used for signaling.
1) Channel Associated Signaling: The DS-1
signaling must be compatible with both the A
and B bit signaling protocol of Channel Asso-
ciated Signaling (CAS), used by a D4 type
channel bank. In this protocol, the least signifi-
Pulse Density Restriction: Since regenerative
repeaters are used in the transmission facility, a
restriction on the transmission of data has been
imposed upon. This restriction is designed to pre-
vent a clock recovery failure (due to an excessive
number of "ZEROS") from happening. The restric-
n SUPERFRAM _I
FRAME FRAME
FRAME
SIGNALING FRAMING (FS)
TERMINAL FRAMING (FT)
FIGURE 2-D4 FRAMING FORMAT
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