IDT82V2048(2010) データシートの表示（PDF） - Integrated Device Technology

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IDT82V2048
(Rev.:2010)

OCTAL T1/E1 SHORT HAUL LINE INTERFACE UNIT

Integrated Device Technology 

IDT82V2048 OCTAL T1/E1 SHORT HAUL LINE INTERFACE UNIT

INDUSTRIAL TEMPERATURE RANGES

Table-7 AIS Condition

AIS Detected

AIS Cleared

ITU G.775 for E1

(Register LAC defaulted to ‘0’)

Less than 3 zeros contained in each of two

consecutive 512-bit stream are received

3 or more zeros contained in each of two

consecutive 512-bit stream are received

ETSI 300 233 for E1

(Register LAC set to ‘1’)

Less than 3 zeros contained in a 512-bit

stream are received

3 or more zeros contained in a 512-bit

stream are received

ANSI T1.231 for T1

Less than 9 zeros contained in a 8192-bit stream (a ones

density of 99.9% over a period of 5.3 ms) are received

9 or more zeros contained in a 8192-bit stream are

received

Table-8 Error Detection

Hardware Mode

Line Code Pin CVn Reports

AMI

Bipolar Violation

B8ZS/

HDB3

Bipolar Violation +

Code Violation

Host Mode

Line Code CODVn in e-CODV CZERn in e-CZER

Pin CVn Reports

AMI

-

-

Bipolar Violation

0

0

Bipolar Violation + Code Violation

B8ZS/HDB3

0

1

1

Bipolar Violation + Code Violation + Excessive Zeros

0

Bipolar Violation

1

1

Bipolar Violation + Excessive Zeros

2.4.6.1 BPV DETECTION AND REPORTING IN AMI LINE CODING

AMI stands for Alternative Mark Inversion. It uses bipolar pulses to

represent logical values. A logic 0 is represented by no symbol and a

logic 1 by pulses of alternating polarity. In AMI line coding, marks

(pulses) are transmitted or received alternatively on tip and ring. If a

mark (pulse) is transmitted or received in the same polarity as the prior

mark (pulse), it is a bipolar violation.

Bipolar violation (BPV) is a non-zero signal element in an AMI signal

that has the same polarity as the previous non-zero signal element.

RCLKn

RTIPn 1

3

5

V

7

RRINGn

2

4

6

RDn

1

2

34

5

V

6

CVn

Bipolar Violation

Bipolar Violation detected

Figure-7 AMI Bipolar Violation

2.4.6.2 EXZ AND BPV DETECTION IN HDB3

The purpose of HDB3 is to prevent transmission of more than 3

consecutive zeros while maintaining DC balance. HDB3 encoder will

encode any 4 consecutive zeros as 000V or B00V where V is a bipolar

violation and B is a balancing pulse that is opposite in polarity to the

previous V. If there is an odd number of B pulses since the last V, then

the four consecutive zeros will be substituted as 000V. If there is an even

number of B pulses since the last V, then B00V substitution is chosen.

The HDB3 decoder, once receiving correctly encoded 000V or B00V, will

automatically restore the pattern back into 4 consecutive zeros.

HDB3 decoder will report an EXZ (excessive zero) when it receives 4

consecutive zeros.

The detection of code violation in 000V, coded for 4 consecutive

zeros in HDB3 line coding, depends on the number of alternate ones

between two consecutive ‘V’ (code violation) in the input data pattern. If

the number of alternate ones between two consecutive violations is an

odd number, no violation detection is reported. In Figure-8 input pattern,

there is one code violation detection for two 000V patterns. It can be

inferred that in Figure-8, there is another code violation prior to the first

000V pattern, and the number of alternate pulses between these two

violations is an odd number.

Conversely, if the number of alternate pulses between two violations

is an even number, there is a code violation reported for 000V as in

Figure-9.

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