DS26521 datasheet(56/258 Pages) MAXIM

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DS26521 Single T1/E1/J1 Transceiver

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Table 8-21. E1 Line Code Violation Counting Options

E1 CODE VIOLATION SELECT

(ERCNT.0)

WHAT IS COUNTED IN

LCVCR1, LCVCR2

BPVs

CVs

8.9.9.2 Path Code Violation Count Register (PCVCR)

In T1 operation, the Path Code Violation Count register (PCVCR) records either Ft, Fs, or CRC-6 errors. When the

receive side of a framer is set to operate in the T1 ESF framing mode, PCVCR records errors in the CRC-6

codewords. When set to operate in the T1 D4 framing mode, PCVCR counts errors in the Ft framing bit position.

Via the ERCNT.2 bit, a framer can be programmed to also report errors in the Fs framing bit position. PCVCR is

disabled during receive loss of synchronization (RLOF = 1) conditions. See Table 8-22 for a detailed description of

exactly what errors the PCVCR counts in T1 operation.

In E1 operation, PCVCR records CRC-4 errors. Since the maximum CRC-4 count in a one-second period is 1000,

this counter cannot saturate. The counter is disabled during loss of sync at either the FAS or CRC-4 level; it

continues to count if loss of multiframe sync occurs at the CAS level.

The Path Code Violation Count Register 1 (PCVCR1) is the most significant word and Path Code Violation Count

Table 8-22. T1 Path Code Violation Counting Arrangements

FRAMING MODE

COUNT Fs ERRORS?

WHAT IS COUNTED IN

PCVCR1, PCVCR2

Errors in the Ft pattern

Yes

Errors in both the Ft and Fs patterns

ESF

Don’t Care

Errors in the CRC-6 codewords

8.9.9.3 Frames Out of Sync Count Register (FOSCR)

The FOSCR is used to count the number of multiframes that the receive synchronizer is out of sync. This number is

useful in ESF applications needing to measure the parameters loss of frame count (LOFC) and ESF error events

as described in AT&T publication TR54016. When the FOSCR is operated in this mode, it is not disabled during

receive loss of synchronization (RLOF = 1) conditions. The FOSCR has an alternate operating mode whereby it will

count either errors in the Ft framing pattern (in the D4 mode) or errors in the FPS framing pattern (in the ESF

mode). When the FOSCR is operated in this mode, it is disabled during receive loss of synchronization (RLOF = 1)

conditions. See Table 8-23 for a detailed description of what the FOSCR is capable of counting.

In E1 mode, the FOSCR counts word errors in the frame alignment signal in time slot 0. This counter is disabled

when RLOF is high. FAS errors will not be counted when the framer is searching for FAS alignment and/or

synchronization at either the CAS or CRC-4 multiframe level. Since the maximum FAS word error count in a one-

second period is 4000, this counter cannot saturate.

The Frames Out of Sync Count Register 1 (FOSCR1) is the most significant word and Frames Out of Sync Count

Table 8-23. T1 Frames Out of Sync Counting Arrangements

FRAMING MODE

(RCR1.5)

COUNT MOS OR F-BIT ERRORS

(ERCNT.1)

WHAT IS COUNTED IN

FOSCR1, FOSCR2

MOS

Number of multiframes out of sync

F-Bit

Errors in the Ft pattern

ESF

MOS

Number of multiframes out of sync

ESF

F-Bit

Errors in the FPS pattern

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