DS2155 datasheet(82/262 Pages) DALLAS

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DS2156

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13.1 Line-Code Violation Count Register (LCVCR)

13.1.1

T1 Operation

T1 code violations are defined as bipolar violations (BPVs) or excessive 0s. 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 13-A shows what the LCVCRs

count.

Table 13-A. T1 Line Code Violation Counting Options

COUNT EXCESSIVE

ZEROS?

(ERCNT.0)

B8ZS ENABLED?

(T1RCR2.5)

COUNTED IN THE LCVCRs

BPVs

Yes

BPVs + 16 consecutive 0s

Yes

BPVs (B8ZS codewords not counted)

Yes

BPVs + 8 consecutive 0s

13.1.2

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 does not roll over. The bit-error rate on an E1 line would

have to be greater than 10-2 before the VCR would saturate (Table 13-B).

Table 13-B. E1 Line-Code Violation Counting Options

E1 CODE VIOLATION SELECT

(ERCNT.3)

COUNTED IN THE LCVCRs

BPVs

CVs

DS2155 Datasheet(PDF) 82 Page - Dallas Semiconductor