XRT73R12_07 Datasheet, PDF (26/89 Pages) Exar Corporation – TWELVE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT

XRT73R12
TWELVE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT
REV. 1.0.2
TABLE 3: THE ALOS (ANALOG LOS) DECLARATION AND CLEARANCE THRESHOLDS FOR A GIVEN SETTING OF
REQEN (DS3 AND STS-1 APPLICATIONS)
APPLICATION REQEN SETTING
DS3
0
1
STS-1
0
1
SIGNAL LEVEL TO DECLARE ALOS SIGNAL LEVEL TO CLEAR ALOS
DEFECT
DEFECT
< 41mVpk
> 102mVpk
< 52mVpk
> 117mVpk
< 51mVpk
> 114mVpk
< 58mVpk
> 133mVpk
3.5.2 Disabling ALOS/DLOS Detection
For debugging purposes it is useful to disable the ALOS and/or DLOS detection. Writing a “1” to both
ALOSDIS_n and DLOSDIS_n bits disables the LOS detection on a per channel basis.
3.5.3 E3 LOS Condition:
If the level of incoming line signal drops below the threshold as described in the ITU-T G.775 standard, the
LOS condition is detected. Loss of signal is defined as no transitions for 10 to 255 consecutive zeros. No
transitions is defined as a signal level between 15 and 35 dB below the normal. This is illustrated in Figure 8.
The LOS condition is cleared within 10 to 255 UI after restoration of the incoming line signal. Figure 9 shows
the LOS declaration and clearance conditions.
FIGURE 8. LOSS OF SIGNAL DEFINITION FOR E3 AS PER ITU-T G.775
0 dB
-12 dB
-15dB
LOS Signal Must be Cleared
Maximum Cable Loss for E3
-35dB
LOS Signal may be Cleared or Declared
LOS Signal Must be Declared
23