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XRT7300
E3/DS3/STS-1 LINE INTERFACE UNIT
REV. 1.1.1
FIGURE 21. THE SIGNAL LEVELS THAT THE XRT7300 DECLARES AND CLEARS LOS (E3 MODE ONLY)
0 dB
Maximum Cable Loss for E3
LOS Signal Must be Cleared
-12 dB
-15dB
LOS Signal may be Cleared or Declared
-35dB
LOS Signal Must be Declared
Timing Requirements associated with Declaring
and Clearing the LOS Indicator for E3 Applica-
tions
(or E3 bit-periods) after the actual time the LOS con-
dition occurred. Further, the XRT7300 clears the
LOS indicator within 10 to 255 UI after restoration of
the incoming line signal. Figure 22 illustrates the
LOS Declaration and Clearance behavior in response
to the first loss of signal event and then afterwards to
the restoration of the signal.
The XRT7300 was designed to meet the ITU-T G.775
specification timing requirements for declaring and
clearing the LOS indicator. In particular, the
XRT7300 declares an LOS between 10 and 255 UI
FIGURE 22. THE BEHAVIOR THE LOS OUTPUT INDICATOR IN RESPONSE TO THE LOSS OF SIGNAL AND THE RESTO-
RATION OF SIGNAL
Actual Occurrence
of LOS Condition
Line Signal
is Restored
RTIP/
RRing
Time Range for
LOS Declaration
10 UI
10 UI
255 UI
255 UI
RLOS Output Pin
0 UI
0 UI
G.775
Compliance
Time Range for
LOS Clearance
G.775
Compliance
31
EXAR [ EXAR CORPORATION ]
