EXFO PSO-200 Optical Modulation Analyzer - Manual (Page 113)

Bit Pattern Analysis and the Gearbox
Optical Modulation Analyzer 105
Obtaining and Using Bit/Symbol Error Rates
Obtaining and Using Bit/Symbol Error Rates
Since the PSO-200 is not a real-time oscilloscope, the sampled symbols will
not make a continuous set that can be directly compared with a reference
symbol pattern. Even though the symbols are not sampled in order, after
time-base reconstruction and constellation sample selection, the symbol
error rate (SER) can be evaluated.
To obtain the bit error rate (BER), you have to provide the expected bit
pattern (PRBS or user-defined). The BER is a bit-to-bit comparison
between the measured and expected patterns, performed on every
acquired sample contained in the measurement window.
The BER is updated with each new burst processed (current number of
errors = previous number + new number). The current burst BER and the
total BER (from the start of the acquisition) are both displayed.
Note: When clicking Start or Clear in the application, BER results are reset, like
all other measurements.
Note: BER/SER values cannot be computed in Averaging mode.
BER
Total number of non-matching bits
Total number of bits verified
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