XRT73LC03A Datasheet, PDF (42/61 Pages) Exar Corporation – 3 CHANNEL DS3/E3/STS-1 LINE INTERFACE UNIT

XRT73LC03A
3 CHANNEL DS3/E3/STS-1 LINE INTERFACE UNIT
REV. 1.0.1
ITU-T Recommendation G.775 for both E3 and DS3
applications.
3.5.1 The LOS Declaration/Clearance Criteria
for E3 Applications
When the XRT73LC03A is operating in the E3 Mode,
a given channel declares an LOS Condition if its re-
ceive line signal amplitude drops to -35dB or below.
Further, the channel clears the LOS Condition if its
receive line signal amplitude rises back to -15dB or
above. Figure 26 illustrates the signal levels at which
each channel of the XRT73LC03A declares and
clears LOS.
FIGURE 26. THE SIGNAL LEVELS THAT THE XRT73LC03A DECLARES AND CLEARS LOS
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
Timing Requirements associated with Declaring
and Clearing the LOS Indicator
The XRT73LC03A was designed to meet the ITU-T
G.775 specification timing requirements for declaring
and clearing the LOS indicator. In particular, a chan-
nel declares an LOS between 10 and 255 UI (or E3
bit-periods) after the actual time the LOS condition
occurred. Further, the channel clears the LOS indica-
tor within 10 to 255 UI after restoration of the incom-
ing line signal. Figure 27 illustrates the LOS Declara-
tion and Clearance behavior in response to the Loss
of Signal event and then the restoration of the signal.
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