XRT75R12D_06 Datasheet, PDF (124/134 Pages) Exar Corporation – TWELVE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET

XRT75R12D
TWELVE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCHRONIZER REV. 1.0.1
JITTER ATTENUATOR CONTROL REGISTER - CHANNEL 0 ADDRESS LOCATION = 0X07
CHANNEL 1 ADDRESS LOCATION = 0X0F
CHANNEL 2 ADDRESS LOCATION = 0X17
BIT 7
R/O
0
BIT 6
Unused
R/O
0
BIT 5
R/O
0
BIT 4
BIT 3
SONET APS
Recovery
Time
DisableCh_n
JA RESET
Ch_n
R/W
R/W
0
0
BIT 2
JA1 Ch_n
BIT 1
JA in Tx Path
Ch_n
BIT 0
JA0 Ch_n
R/W
R/W
R/W
0
1
1
• If the LIU has been configured to operate in the Hardware Mode.
Then the user should tie pin 43 (JATx/JARx*) to "1".
e. Enable the "SONET APS Recovery Time" Mode
Finally, if the user intends to use the LIU in an Application that is required to reacquire proper SONET and DS3
traffic, prior within 50ms of an APS (Automatic Protection Switching) event (per Telcordia GR-253-CORE), then
the user should set Bit 4 (SONET APS Recovery Time Disable), within the "Jitter Attenuator Control" Register,
to "0" as depicted below.
JITTER ATTENUATOR CONTROL REGISTER - CHANNEL 0 ADDRESS LOCATION = 0X07
CHANNEL 1 ADDRESS LOCATION = 0X0F
CHANNEL 2 ADDRESS LOCATION = 0X17
BIT 7
R/O
0
BIT 6
Unused
R/O
0
BIT 5
R/O
0
BIT 4
BIT 3
SONET APS
Recovery
Time
DisableCh_n
JA RESET
Ch_n
R/W
R/W
0
0
BIT 2
JA1 Ch_n
BIT 1
JA in Tx Path
Ch_n
BIT 0
JA0 Ch_n
R/W
R/W
R/W
0
0
1
NOTES:
1. The ability to disable the "SONET APS Recovery Time" mode is only available if the LIU is operating in the Host
Mode. If the LIU is operating in the "Hardware" Mode, then this "SONET APS Recovery Time Mode" feature will
always be enabled.
2. The "SONET APS Recovery Time" mode will be discussed in greater detail in “Section 8.8.3, How does the
LIU permit the user to comply with the SONET APS Recovery Time requirements of 50ms (per
Telcordia GR-253-CORE)?” on page 123.
8.8.2 Recommendations on Pre-Processing the Gapped Clocks (from the Mapper/ASIC Device)
prior to routing this DS3 Clock and Data-Signals to the Transmit Inputs of the LIU
In order to minimize the effects of "Clock-Gapping" Jitter within the DS3 signal that is ultimately transmitted to
the DS3 Line (or facility), we recommend that some "pre-processing" of the "Data-Signals" and "Clock-Signals"
(which are output from the Mapper device) be implemented prior to routing these signals to the "Transmit
Inputs" of the LIU.
8.8.2.1 SOME NOTES PRIOR TO STARTING THIS DISCUSSION:
119