Exfo PSO-200 Optical Modulation Analyzer Manual de usuario descargar pdf (Pagina 24)

Setting Up the Optical Modulation Analyzer

16 PSO-200

Setting Other Acquisition Parameters

Use the following parameters to improve the recovered waveform:

 Burst sampling parameters: you can specify the number of bursts that

will be recorded or buffered by the application, as well as the number

of data points in each burst. A larger number of points will take more

time to process but provide better results.

 Input pattern mode and parameters: available modes depend on the

selected modulation scheme.

 Random – if random signals (live traffic or framed PRBS) or very

long patterns (2

-1 PRBS) are used. The constellation chart and

eye diagrams of amplitude and phase can be measured, but not

the patterns. No filtering, averaging or CD unwrapping possible.

 Repetitive (unknown pattern) – if your signal under test comprises

a repetitive pattern with known word length (for example, PRBS

with header data). The pattern can also be recovered.

 User-defined symbol pattern – if you know exactly the symbol

pattern or can extract it from an acquisition (such as in Repetitive

mode or if your modulation scheme is not supported by the

PSO-200). This mode improves signal processing algorithms and

allows the calculation of a symbol error rate (SER). For details, see

Importing User-Defined Symbol Patterns on page 84.

 PRBS – if your signal is generated from pseudo-random binary

sequences. Since the pattern is known, you can obtain bit error

rate (BER) information and you can use the Gearbox to fine-tune

the bit alignment of your signal stream.

 User-defined bit pattern – if you know exactly the sequence of bits

in your signal. As for PRBS, you can obtain the BER and are able to

use the Gearbox.

Note: Free-Run, CW and Intensity Sampling signals do not allow patterns.

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Exfo PSO-200 Optical Modulation Analyzer Manual de usuario Pagina 24