Exfo PSO-200 Optical Modulation Analyzer Manual do Utilizador descarregar pdf (Página 101)

Bit Pattern Analysis and the Gearbox

Optical Modulation Analyzer 93

Performing Detailed Bit Pattern Analysis with the Gearbox

Definition Section

This section describes the type of Gearbox this file addresses. The possible

values of the “Type” field are:

 OneGlobalStream

 NIndividualStreams

 DualXYStreams (only required and supported for dual-polarization

modulation schemes)

There is one file per Gearbox streaming type and per modulation scheme.

For example, DP-QPSK has three Gearbox configuration files.

The third type (dual X-Y streams) is different from the other two. For a

same modulation format, the “SYMBOLWORDCOORDINATES” section

content has to be seen as two single-polarization configurations. As an

example, see the dual X-Y stream configuration for DP-QPSK (left)

compared to the one global stream configuration for QPSK (right).

As these examples show, the dual X-Y streams configuration represents the

same configuration as twice the single-polarization “one global stream”.

In dual X-Y streams, the “SYMBOLWORDCOORDINATES” section does not

seem to contain all possible bit combinations, but it does. In the example,

the word “0000” is, in fact, “00” of polarization “X” and “00” of polarization

“Y”. With two bits per polarization, there are only four possible words.

For details about the Gearbox types, see Gearbox Streaming Types on

page 88.

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Exfo PSO-200 Optical Modulation Analyzer Manual do Utilizador Página 101