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XRT83SH38
25
8-CHANNEL T1/E1/J1 SHORT-HAUL LINE INTERFACE UNIT
REV. 1.0.7
FIGURE 12. ANALOG RECEIVE LOS OF SIGNAL FOR T1/E1/J1
NOTE: For programming the equalizer gain setting on a per channel basis, see the microprocessor register map for details.
3.2.3.2
EXLOS (Extended Loss of Signal)
By enabling the extended loss of signal by programming the appropriate channel register, the digital RLOS is
extended to count 4,096 consecutive zeros before declaring RLOS in T1 and E1 mode. By default, EXLOS is
disabled and RLOS operates in normal mode.
3.2.3.3
AIS (Alarm Indication Signal)
The XRT83SH38 adheres to the ITU-T G.775 specification for an all ones pattern. The alarm indication signal
is set to "1" if an all ones pattern (at least 99.9% ones density) is present for T, where T is 3ms to 75ms in T1
mode. AIS will clear when the ones density is not met within the same time period T. In E1 mode, the AIS is
set to "1" if the incoming signal has 2 or less zeros in a 512-bit window. AIS will clear when the incoming signal
has 3 or more zeros in the 512-bit window.
3.2.3.4
FLSD (FIFO Limit Status Detection)
The purpose of the FIFO limit status is to indicate when the Read and Write FIFO pointers are within a pre-
determined range (over-flow or under-flow indication). The FLSD is set to "1" if the FIFO Read and Write
Pointers are within ±3-Bits.
3.2.3.5
LCVD (Line Code Violation Detection)
The LIU contains 8 independent, 16-bit LCV counters. When the counters reach full-scale, they remain
saturated at FFFFh until they are reset globally or on a per channel basis. For performance monitoring, the
counters can be updated globally or on a per channel basis to place the contents of the counters into holding
registers. The LIU uses an indirect address bus to access a counter for a given channel. Once the contents of
the counters have been placed in holding registers, they can be individually read out 8-bits at a time according
to the BYTEsel bit in the appropriate global register. By default, the LSB is placed in the holding register until
the BYTEsel is pulled "High" where upon the MSB will be placed in the holding register for read back. Once
both bytes have been read, the next channel may be selected for read back.
By default, the LVC/OFD will be set to a "1" if the receiver is currently detecting line code violations or
excessive zeros for HDB3 (E1 mode) or B8ZS (T1 mode). In AMI mode, the LCVD will be set to a "1" if the
receiver is currently detecting bipolar violations or excessive zeros. However, if the LIU is configured to
TABLE 6: ANALOG RLOS DECLARE/CLEAR (TYPICAL VALUES) FOR T1/E1
GAIN SETTING
DECLARE
CLEAR
15dB (Short Haul Mode)
-24dB
-21dB
29dB (Monitoring Gain Mode)
-38dB
-35dB
Normalized up to EQC[4:0] Setting
Declare LOS
Clear LOS
-9dB
+3dB
Clear LOS
Declare LOS
+3dB
-9dB
Normalized up to EQC[4:0] Setting