Agilent Technologies J-BERT N4903, User Manual

Page: 16 / 434

N O T E
The test times in this table are valid for continuous measurements. If measurements
are made in bursts, the test times will be longer (continuous test time divided by
the burst duty cycle times the burst sync ratio). See
“Introduction to Burst Sync
Mode” on page 144 for background information.
The test times for 95% confidence level are:
Table 2
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-14 ~ 8.4 hours ~ 1.4 days ~ 5.6 days ~ 22.4 days
1E-13 ~ 50 minutes ~ 3.3 hours ~ 13 hours ~ 2.2 days
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
1
Planning the Test
16 Agilent J-BERT N4903 High-Performance Serial BERT