XRT73LC00AIV-F Datasheet, PDF (41/61 Pages) Exar Corporation – E3/DS3/STS-1 LINE INTERFACE UNIT

REV. 1.0.2
XRT73LC00A
E3/DS3/STS-1 LINE INTERFACE UNIT
3.6.1 The LOS Declaration/Clearance Criteria for E3 Applications
When the XRT73LC00A is operating in the E3 Mode, it declares an LOS Condition if the signal amplitude
drops to -35dB or below. The XRT73LC00A clears the LOS Condition if the signal amplitude rises back up to -
15dB or above. Figure 22 illustrates the signal levels at which the XRT73LC00A asserts and clears LOS.
FIGURE 22. THE SIGNAL LEVELS THAT THE XRT73LC00A DECLARES AND CLEARS LOS (E3 MODE ONLY)
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 for E3 Applications
The XRT73LC00A was designed to meet the ITU-T G.775 specification timing requirements for declaring and
clearing the LOS indicator. The XRT73LC00A declares an LOS between 10 and 255 UI or E3 bit-periods after
the actual time the LOS condition occurred. The XRT73LC00A clears the LOS indicator within 10 to 255 UI
after restoration of the incoming line signal. Figure 23 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.
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