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PEB 3445 E
Register Description
Data Sheet
101
2001-06-29
N
r
/AICC
N
r
-bit Image (C-bit parity format only)
This bit contains an image of the DS3 frame overhead bit in block 5 of
subframe 1. It is updated only if its state persists for 3 multiframes and
DS3 frame is aligned.
AIC-bit Changed (M13 asynchronous format)
This bit indicates a change of the AIC-bit (first C-bit of the first subframe)
since the last read of this register.
AIC-bit Image (DS3 frame overhead bit in block 3 of subframe 1)
This bit contains an image of the DS3 frame overhead bit in block 3 of
subframe 1. It is updated only if its state persists for 3 multiframes and
DS3 frame is aligned.
X-bit Image (DS3 frame overhead bit in block 1 of subframes 1 and 2)
This bit contains an image of the DS3 frame overhead bit in block 1 of
subframes 1 and 2. It is updated only if both overhead have the same
value, when its state persists for 3 multiframes and when the DS3 frame
is aligned.
DS3 Idle Signal State
This bit indicates that the idle pattern (framed ...1100... with C-bits=’0’ in
subframe 3 and X-bits=’1’) was persistent as per alarm timing
parameters defined in register D3RAP. Idle is considered active in a
multiframe when fewer than 15 errors are detected. At 10
-3
error rates,
5 errors per multiframe are typical. The exact time necessary to change
the flag could be greater if the FAS flag is not constant. The frame
alignment state is integrated by incrementing or decrementing a counter
at the end of each multiframe when the FAS flag is set or cleared
respectively.
DS3 Alarm Indication Signal State
This bit indicates the AIS alarm state. AIS can be a framed ’..1010..’
pattern with C-bits=’0’ and X-bits=’1’ or an unframed all ‘1’ pattern. This
is determined by D3TCFG.AISC. AIS is considered active in a
multiframe when fewer than 15 errors are detected and is declared when
it was persistent as per alarm timing parameters defined in register
D3RAP. At 10
-3
error rates, 5 errors per multiframe are typical. The exact
time necessary to change the flag could be greater if the FAS flag is not
constant. The frame alignment state is integrated by incrementing or
decrementing a counter at the end of each multiframe when the FAS flag
is set or cleared respectively.
AIC
XBIT
IDLES
AISS