![](http://datasheet.mmic.net.cn/IDT--Integrated-Device-Technology-Inc/IDT82V2048DAG_datasheet_97508/IDT82V2048DAG_17.png)
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IDT82V2048 OCTAL T1/E1 SHORT HAUL LINE INTERFACE UNIT
INDUSTRIAL TEMPERATURE RANGES
Figure-8 HDB3 Code Violation & Excessive Zeros
Figure-9 HDB3 Code Violations & Two BPV Detections
2.4.6.3 EXZ AND BPV DETECTION IN B8ZS
B8ZS (Binary 8 Zero Substitution) is an AMI line code with the substi-
tution of a unique code to replace occurrences of eight consecutive zero
signal elements. Each block of eight successive zeros is replaced by
000VB0VB, where B represents an inserted non-zero signal element,
and V represents an inserted non-zero signal element that is a bipolar
violation.
Bipolar violation (BPV) is a non-zero signal element that has the
same polarity as the previous non-zero signal element. in normal B8ZS
line coding for 8 contiguous zeros, two BPV signals are deliberately
inserted. BPV in this case is not an error. Therefore, data and error
pulses will not appear on RDn and CVn pins in this BPV case. Some-
times, a BPV occurs as a result of transmission line noise or interfer-
ence. As such, it is an error and should be detected and reported.
An excessive zeros (EXZ) for a B8ZS-coded signal is the occurrence
of any zero-string length greater than seven contiguous zeros.
As shown in
Figure-11, all three bipolar violations (pulse ‘2’, ‘4’ and
‘5’) in the input data pattern are treated as individual code violations:
they are recovered as data bits in RD signal line and a BPV is detected
for each of the three violated pulses.
Code violation detected
Excessive zeros detected
RCLKn
RTIPn
RRINGn
RDn
CVn
Code violation
4 consecutive zeros
1
2
3
4V
V
5
6
12
3
4
5
6
RCLKn
RTIPn
RRINGn
RDn
CVn
1
B
V
3V
0
2
5
12
5
6
46
V
0
00
0
V
0
7
34
7
VV
V
000