BT8376EPF datasheet(190/323 Pages) CONEXANT

190 / 323 page

Bt8370/8375/8376

3.12 Transmitter Registers

Fully Integrated T1/E1 Framer and Line Interface

3-72

Conexant

N8370DSE

TLOFC–TLOFA

Transmit Loss of Frame Criteria—Determines the number of frame errors that the online

framer must detect before declaring a loss of frame alignment [TLOF; addr 048]. Refer to

TFRAME [addr 070] to find which frame bits are monitored during the selected framer mode.

TZCS[1:0]

Transmit Zero Code Suppression—Selects ZCS and Pulse Density Violation (PDV)

enforcement options for XTIP/XRING and TPOSO/TNEGO outputs. B8ZS and HDB3

replace transmitted sequences of eight or four 0s with a recoverable code. These are standard

T1 and E1 line code options, respectively (see Table 3-20).

T1/E1N

TLOFC–A

Reframe Criteria

100

3 consecutive FAS errors

001

2 out of 4 frame bit errors

010

2 out of 5 frame bit errors

100

2 out of 6 frame bit errors

NOTE(S):

All other TLOFC–A combinations are invalid.

Table 3-20. Transmit Zero Code Suppression

TZCS

T1/E1N

T1DM

ZCS

PDV

Zero Code Substitution

(Sent left to right)

AMI

None

HDB3

None

000V or B00V

B8ZS

None

000VB0VB

UMC

None

10011000

AMI

Enforced

on PDV errors

AMI

Alternate Mark Inversion. Bipolar line code forces successive 1s to alternate their output pulse polarity. Analog and

digital dual-rail outputs are always AMI encoded, although certain AMI codes are modified to include 0 suppression.

HDB3

Prior to transmission, four consecutive 0s are substituted by 000V or B00V code, where B is an AMI pulse, and V is a

bipolar violation. ZCS encoder selects the code that forces the BPV output polarity opposite that of the prior BPV.

B8ZS

Prior to transmission, eight consecutive 0s are substituted by 000VB0VB code, where B is an AMI encoded pulse, and

V is a bipolar violation.

PDV

Enforcer overwrites transmit 0s that would otherwise cause output data to fail to meet the minimum required pulse

density per ANSI T1.403 sliding window.

NOTE(S):

The enforcer never overwrites a framing bit and is not applicable during E1 mode.

NOTE(S):

Each PDV-enforced 1 causes a nonrecoverable, transmitted bit error.

UMC

Unassigned Mux Code. DS0 channels containing eight 0s are substituted with the 10011000 code, per Bellcore

TA-TSY-000278.

NOTE(S):

The receiver's ZCS decoder cannot recover original data content from UMC encoded signal.

NOTE(S):

PRBS, inband loopback, and YB2 alarm insertion occurs after PDV enforcement; therefore, output data might violate

minimum pulse density requirements while these functions are active.

BT8376EPF Datasheet(PDF) 190 Page - Synaptics Incorporated.

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