PM4328 View Datasheet(PDF) - PMC-Sierra
Part Name
Description
MFG CO.
'PM4328' PDF : 250 Pages View PDF
STANDARD PRODUCT
DATASHEET
PMC-2011596
ISSUE 1
Figure 29: CRCE Count vs. BER (E1 mode)
PM4328 TECT3
HIGH DENSITY T1/E1 FRAMER
AND M13 MULTIPLEXER
1.00E-02
1.00E-03
1.00E-04
1.00E-05
1.00E-06
1.00E-07
0
200
400
600
800 1000 1200
CRCE
Figure 30 illustrates the expected count values for a range of Bit Error Ratios in
T1 mode.
Figure 30: FER Count vs. BER (T1 ESF mode)
9
)8
2-
10 7
x( 6
aet 5
Rorrr
4
BEt i
3
2
Average Count Over
Many 1 Second Intervals
1
0
0
50
100
150
200
250
Framing Bit Error Count Per Second
Since the maximum number of ESF superframes that can occur in one second is
333, the 9-bit BEE counter cannot saturate in one second in ESF framing format.
Despite this, there is not a linear relationship between BER and BEE count, due
to the nature of the CRC-6 calculation. At BERs below 10-4, there tends to be no
more than one bit error per superframe, so the number of CRC-6 errors is
generally equal to the number of bit errors, which is directly related to the BER.
However, at BERs above 10-4, each CRC-6 error is often due to more than one
bit error. Thus, the relationship between BER and BEE count becomes non-
linear above a 10-4 BER. This must be taken into account when using ESF
CRC-6 counts to determine the BER.
PROPRIETARY AND CONFIDENTIAL
139
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