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PERCEPTIONeb,,
Tl/DS-1
SEPTEMBER1991
tion imposes
that in every frame
of 8(n+l)
bits,
where
n = 1 - 23, there must be at least an "n"
number
of "ONE." There can also be no more than
15 consecutive
"ZEROS" present.
To comply with
these
requirements,
the Tl/DS-1
interface
pro-
vides the following
two techniques:
1) Zero Code
Suppression
(ZCS): This tech-
nique forces the second least significant
bit of
any time slot with eight consecutive
"ZEROS"
to "ONE."
2)
Bipolar
Eight
Zero
Substitution
(B8ZS):
This technique
provides
a unique algorithm.
Whenever
a time slot contains eight consecu-
tive "ZEROS," the "ZEROS" are replaced by an
8-bit code (OOOll O-j.1). The bipolar violation
occurs in the fourth and the seventh
bit posi-
tions of the inserted
code. The receiving
end
recognizes
this code, and it translates
it into all
"ZEROS" (see Figure 3).
Voice and Data Applications:
The Tl/DS-1
trunk
TIE) provides
a feature
transparency
to voice and
datatransmission
applications.
PERCEPTIONeLex
supports
voice only with the NDTU.
Data trans-
mission must be done through
a modem or modem
pooling.
Synchronization:
The PERCEPTIONeLex
Tl/DS-
1 interface can support two types of clock synchro-
nization.
It can either generate
the clock reference
internally
(Master)
to the public digital or private
digital
network,
or attain
clock (Slave)
from the
external digital network.
In case there is more than
oneTl/DS-1
trunkinstalledin
PERCEPTIONehex,
only one will provide
the clock synchronization
signal. When connecting
PERCEPTIONehex
to the
network,
PERCEPTIONeLex
will always be slave.
Out of Frame (OOF)
An Out of Frame (OOF) condition
occurs when an
error in the framing
bit is observed.
An error is
considered
to have happened
when two out of four,
or two out of five framing
bits are absent.
This
capability
to emulate
different
trunks
(CO, DID,
condition
causes the MFALM
LED to light.
ORIGINAL WORD
0
0
0
0
0
0
0
0
SUBSTITUTED
WORD
0
0
0
+I
-1
0
-1
+I
POLARITY*
JJ
*Assume last "ONE" transmitted
was a
positive "ONE. " Polarity is reversed if
the last "ONE" transmitted was a
negative "ONE. 'I Bipolar violations always
occur at the 4th and 7th bit positions.
FIGURES-SAMPLEOFB8ZSCODE
-23-
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