XRT73LC04A
4 CHANNEL DS3/E3/STS-1 LINE INTERFACE UNIT
REV. 1.0.1
When the XRT73LC04A 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 XRT73LC04A declares and
clears LOS.
F
IGURE
26. T
HE
S
IGNAL
L
EVELS THAT THE
XRT73LC04A
DECLARES AND CLEARS
LOS
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
The XRT73LC04A 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.
40
EXAR [ EXAR CORPORATION ]
