XRT75VL00D datasheet(89/92 Pages) EXAR

89 / 92 page

XRT75VL00D

REV. 1.0.3

E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCHRONIZER

that are responsible for acquiring and maintaining DS1 or DS3 frame synchronization (with these DS1 or DS3

data-streams that have been de-mapped from SONET) must have re-acquired DS1 or DS3 frame

synchronization within 50ms" after APS has been initiated."

The LIU was designed such that the DS3 signals that it receives from a SONET Mapper device and processes

will comply with the Category I Intrinsic Jitter requirements per Telcordia GR-253-CORE.

Reference 1 documents some APS Recovery Time testing, which was performed to verify that the Jitter

Attenuator blocks (within the LIU) device that permit it to comply with the Category I Intrinsic Jitter

Requirements (for DS3 Applications) per Telcordia GR-253-CORE, do not cause it to fail to comply with the

"APS Completion Time" requirements per Section 5.3.3.3 of Telcordia GR-253-CORE.

However, Table 3

presents a summary of some APS Recovery Time requirements that were documented within this test report.

Table 3,

NOTE: The APS Completion (or Recovery) time requirement is 50ms.

Configuring the LIU to be able to comply with the SONET APS Recovery Time Requirements of 50ms

Quite simply, the user can configure a given Jitter Attenuator block (associated with a given channel) to (1)

comply with the "APS Completion Time" requirements per Telcordia GR-253-CORE, and (2) also comply with

the "Category I Intrinsic Jitter Requirements per Telcordia GR-253-CORE (for DS3 applications) by making

sure that Bit 4 (SONET APS Recovery Time Disable Ch_n), within the Jitter Attenuator Control Register is set

to "0" as depicted below.

TABLE 20: MEASURED APS RECOVERY TIME AS A FUNCTION OF DS3 PPM OFFSET

DS3 PPM OFFSET (PER W&G ANT-20SE)

MEASURED APS RECOVERY TIME (PER LOGIC ANALYZER)

-99 ppm

1.25ms

-40ppm

1.54ms

-30 ppm

1.34ms

-20 ppm

1.49ms

-10 ppm

1.30ms

0 ppm

1.89ms

+10 ppm

1.21ms

+20 ppm

1.64ms

+30 ppm

1.32ms

+40 ppm

1.25ms

+99 ppm

1.35ms

JITTER ATTENUATOR CONTROL REGISTER - CHANNEL 0 ADDRESS LOCATION = 0X07

CHANNEL 1 ADDRESS LOCATION = 0X0F

CHANNEL 2 ADDRESS LOCATION = 0X17

BIT 7BIT 6BIT 5

BIT 4BIT 3BIT 2BIT 1BIT 0

Unused

SONET APS

Recovery

Time Disable

Ch_n

JA RESET

Ch_n

JA1 Ch_n

JA in Tx Path

Ch_n

JA0 Ch_n

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