63
Setting the Interfaces - SONET Operation
Setting Transmit Interface
Option 003 only
The definition of NORMAL and INVERTed polarity differs between ITU-T O.150
and common practice usage in the United States of America for 2
15
-1 and 2
23
-1
PRBS patterns.
The PRBS polarity control (see page 193) 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
zeros in a 2
n
-1 PRBS pattern. Therefore selecting INVERT with an ITU-T pattern
will produce a longest string of n-1consecutive ones in a 2
n
-1 pattern.
The ITU-T definition also applies in the US, except for 2
15
-1 and 2
23
-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.
8
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.
9
If VT mapping is chosen for the test STS, choose the PATTERN IN OTHER
VT’s.
SONET_Usr.bk Page 63 Wednesday, December 13, 2000 11:11 AM
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