
10
Serial BERT N4906B, Data Sheet V.3
Patterns
Patterns are used as stimulus data on the genera-
tor as well as expected data on the error detector.
These patterns can be setup commonly for the gen-
erator and error detector or independently.
User-programmable test patterns
User defined patterns are available with
variable length from 1 bit to 33,554,432 bits
(32 Mbit).
Alternate test pattern
Switch between two equal length user
programmable patterns, each up to 16,777,216
bits (16 Mbit). Switching is possible by using a
front panel key, GPIB or the auxiliary input port.
Changeover is synchronous with the end of the
pattern. The length of the alternating patterns
should be a multiple of 512 bits. Two methods of
controlling pattern changeover are available: one-
shot and alternate.
PRBS (HW generated)
2
31
- 1 Polynomial: x
31
+ x
28
+ 1 = 0
(inverted)
2
23
- 1 Polynomial: x
23
+ x
18
+ 1 = 0
(inverted) (ITU-T O.151)
2
15
- 1 Polynomial: x
15
+ x
14
+ 1 = 0
(inverted) (ITU-T O.151)
2
11
- 1 Polynomial: x
11
+ x
9
+ 1 = 0
(inverted) (ITU-T O.152)
2
10
- 1 Polynomial: x
10
+ x
7
+ 1 = 0
(inverted)
2
7
- 1 Polynomial: x
7
+ x
6
+ 1 = 0
(inverted) (ITU-T V.29)
Zero substitution
Zeros can be substituted for data to extend the
longest run of zeros in the patterns below. The
longest run can be extended to the pattern length
-1. The bit following the substituted zeros is set to
1.
Variable mark density
The ratio of ones to total bits in the patterns below
can be set to 1/8, 1/4, 1/2, 3/4, or 7/8.
Available test patterns for zero and variables:
• 8388608 bits based on 2
23
PRBS
• 32768 bits based on 2
15
PRBS
• 8192 bits based on 2
13
PRBS
• 2048 bits based on 2
11
PRBS
• 1024 bits based on 2
10
PRBS
• 128 bits based on 2
7
PRBS
•
•
•
•
•
•
10
dataTec GmbH
•
Ferdinand-Lassalle-Str. 52
•
72770 Reutlingen
•
Tel. 07121 / 51 50 50
•
Fax 07121 / 51 50 10
•
info@datatec.de
•
www.datatec.de
Kommentare zu diesen Handbüchern