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MTT-14B e_Manual D07-00-083P RevA00
2.3.4 Test Pattern
To transmit one of the standard patterns:
1. In the screen on the right,
use
to select a
desired pattern. As a pattern
is highlighted, the test set
transmits that pattern.
2. Press INVERT (F2) to send
the pattern with an inverted
polarity (1s and 0s reversed).
Press NORMAL (F2) to send
it with a normal polarity.
The long patterns are written in hexadecimal notation, also known
as 'hex'. A pattern written in hex will be written with pairs of
numbers separated by commas. Hex is a 16 digit number system
consisting of the digits 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F.
The hex pattern 15 FA translates to the binary pattern 0001 0101
1111 1010, where the left most bit is transmitted first.
The following standard test patterns are available:
2e23: Industry-standard 2e23
from a 23 stage shift register. It contains up to 22 zeros in a row and
violates standards for consecutive zeros in AMI transmission.
2e20: Industry-standard 2e20
It is formed from a 20 stage shift register. This pattern contains
up to 19 zeros in a row and violates standards for consecutive
zeros in AMI transmission.
2e15: Industry-standard 2e15
is formed from a 15 stage shift register. It contains up to 14 zeros
in a row and does not violate standards for consecutive zeros in
AMI-coded transmission.
-1
20ITU: This is a 2e20
pseudo random bit sequence. It is formed
from a 20 stage shift register. It conforms to the ITU O.153 techni-
cal standard. It is not identical to 2e20, because different feedback
mechanisms are used when the patterns are produced by means
of shift registers. 20ITU suppresses consecutive sequences of
more than 18 zeros, as opposed to 14 zeros in 2e20.
2047, 511, 127, 63: Industry-standard bit codes used for DDS.
1111: Industry-standard all ones pattern is used for stress testing
E1 AMI and B8ZS lines. If sent unframed, it will be interpreted as
an AIS (Alarm Indication Signal).
1010: Industry-standard alternating ones and zeros pattern. It is
frame aligned with 'f' showing the location of the framing bit.
08:39:57
Meas
>LINK UP
TEST PATTERN
2e23
2e20
2e15
2047
511
127
1111
1-4
1-8
PATTERN :
2e15 INVERT
USER
NORMAL
Figure 39 Test Pattern Screen
-1
pseudo random bit sequence formed
-1
pseudo random bit sequence.
-1
pseudo random bit sequence. It
STU-C E1<
20ITU
63
3-24
Page 60 of 101
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