User guide

Table 3
BER STM-64/
OC-192
(9.95328 Gb/
s)
STM-16c/
OC-48c
(2.48832 Gb/
s)
STM-4c/
OC-12c
(622.08 Mb/s)
STM-1/OC-3
(155.52 Mb/s)
1E-12 ~ 5 minutes ~ 20 minutes ~ 80 minutes ~ 5.3 hours
1E-11 ~ 30 seconds ~ 2 minutes ~ 8 minutes ~ 32 minutes
1E-10 ~ 3 seconds ~ 12 seconds ~ 48 seconds ~ 3.2 minutes
The formula for confidence level is as follows:
C = 1 - e^-nb
Where:
C = degree of confidence (0.95 = 95%)
e = natural base number
n = number of bits examined without error
b = desired residual BER
You may want to prove that your device has a certain residual BER. If you know
this desired BER and the desired confidence level, you can calculate the number
of bits that must be measured without error. The number of bits, in turn, can be
translated into a period of time at a certain bit rate. That is what is done in the
above table.
The following example shows how to calculate the number of bits if the desired
BER (b) is 1E-10 and the desired confidence level (C) is 95%:
1
Change formula "C = 1 - e^-nb" to solve for the number of bits (n)
n = -ln(1-C)/b
2
Replace variables C and b
n = - ln(1 - 0.95)/1E-10
3
Calculate the number of bits
n = - ln(1 - 0.95)/1E-10 = 2.99/1E-10 = 2.99E+10 bits
4
Calculate the time period at the STM-16/OC-48 bit rate (2.48832 Gb/s)
2.99E+10 / 2.48832E+9 = 12.016 seconds
1 Planning the Test
28 Agilent J-BERT N4903B High-Performance Serial BERT