Operator’s Manual
65
Phase Estimation
Lasers are not spectrally pure and they have random phase noise that needs to be corrected. The phase
estimate technique commonly used in wireless transmission is called “Viterbi & Viterbi”. It finds the
average phase error between an ideal symbol on a group of symbols and corrects for it. If the number of
symbols is too low, you will get over-correction. For example, if only one symbol is used, its offset from
the ideal location on the I-Q plane will be considered to be the average, and the symbol will be shifted to
the ideal position when the average phase error is corrected.
The frequency estimate and phase estimate algorithms can be performed on each polarization
independently or you can speed up the processing time by assuming that they are identical for each state
of polarization for dual polarization signals originating from a single laser source (Pols Separately
checkbox).
OMA parameters for phase estimation
For more information on phase noise correction, please refer to:
A. Viterbi. "Nonlinear estimation of PSK-modulated carrier phase with application to burst digital
transmission”, In IEEE transactions on Information Theory, 1983, Volume 29, Issue 4, pp.543-551.
Summary of Contents for IQS25
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