DS21458 datasheet(86/270 Pages) DALLAS

86 / 270 page

DS21455/DS21458 Quad T1/E1/J1 Transceivers

86 of 270

15.1 Line Code Violation Count Register (LCVCR)

15.1.1 T1 Operation

T1 code violations are defined as bipolar violations (BPVs) or excessive zeros. If the B8ZS mode is set

for the receive side, then B8ZS codewords are not counted. This counter is always enabled; it is not

disabled during receive loss of synchronization (RLOS = 1) conditions.

Table 15-1. T1 LINE CODE VIOLATION COUNTING OPTIONS

COUNT EXCESSIVE

ZEROS?

(ERCNT.0)

B8ZS ENABLED?

(T1RCR2.5)

WHAT IS COUNTED IN THE LCVCRs

BPVs

Yes

BPVs + 16 Consecutive Zeros

Yes

BPVs (B8ZS Codewords Not Counted)

Yes

BPVs + 8 Consecutive Zeros

15.1.2 E1 Operation

Either bipolar violations or code violations can be counted. Bipolar violations are defined as consecutive

marks of the same polarity. In this mode, if the HDB3 mode is set for the receive side, then HDB3

codewords are not counted as BPVs. If ERCNT.3 is set, then the LVC counts code violations as defined

in ITU O.161. Code violations are defined as consecutive bipolar violations of the same polarity. In most

applications, the framer should be programmed to count BPVs when receiving AMI code and to count

CVs when receiving HDB3 code. This counter increments at all times and is not disabled by loss of sync

conditions. The counter saturates at 65,535 and will not rollover. The bit error rate on an E1 line would

have to be greater than 10** -2 before the VCR would saturate.

Table 15-2. E1 LINE CODE VIOLATION COUNTING OPTIONS

E1 CODE VIOLATION SELECT

(ERCNT.3)

WHAT IS COUNTED IN THE

LCVCRs

BPVs

CVs

DS21458 Datasheet(PDF) 86 Page - Dallas Semiconductor