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Setting the Interfaces
Setting SDH Transmit Interface
The PRBS polarity control allows the user to select which definition is used on the
TRANSMITTER and RECEIVER windows.
The ITU-T O.150 standard specifies that the NORMAL or default for all PRBS
patterns should be inverted. This will produce a longest string of n-1 consecutive
n
zeros in a 2
-1 PRBS pattern. Therefore selecting INVERT with an ITU-T pattern
n
will produce a longest string of n-1consecutive ones in a 2
-1 pattern.
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The ITU-T definition also applies in the US, except for 2
-1 and 2
-1 PRBS
patterns. Through common practice, NORMAL indicates that the PRBS pattern is
non-inverted. Therefore when the 'US' PRBS polarity control is enable and
NORMAL is selected for these two patterns on the TRANSMITTER, a longest
string of n-1 consecutive ones is produced. The pattern has to be INVERTed in order
to produce a longest string of n-1 consecutive zeros.
Choose the mapping required in the background (non-test) STS's. Refer to
Appendix A for a table of background patterns for STS-1 SPE.
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