Tektronix OM4006D, User Manual

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Core Processing function reference
Theta.Ce (Theta.Values(end)-Theta.Values(1))/2/pi/number of
symbols/Theta.dt
Although it reports the same value for .CentFreq every block, the function
internally estimates a new heterodyne offset frequency for each block. This means
that it is able to track a slowly varying frequency change. The block size must be
smaller than the time taken for the frequency to shift in order to track it accurately.
The phase calculate internally is adjusted for the reported .CentFreq (calculated
in the
fi rst block), so that the reported Theta.CentFreq and Theta.Values are
consistent. The user can differentiate Theta.Values to see the changing frequency,
perhaps with a large step size to effectively average the result.
References M.G. Taylor, "Phase Estimation Methods for Optical Coherent Detection Using
Digital Signal Processing," IEEE J. Lightwave Technol., vol. 27, no. 7, p.
901-914, 2009.
EstimateSOP
[RotM,BoundValsOut,AlertsOut] =
EstimateSOP(pSym,SigType,BoundValsIn,AlertsIn)
pSym – dual-polarization description of optical signal, at symbol center times:
.t0 – time of fi rst symbol
.dt – symbol duration
.Values – 2xN array (row of Jones vectors), symbol center signal values
SigType – integer value indicating signal modulation format
BoundValsIn – structure of boundary values from previous block
AlertsIn – structure of alerts accumulated before executing function
RotM – 2x2 matrix (Jones matrix) containing axes of polarization states of
signal tributaries BoundValsOut – structure of boundary values to be passed
to next block
AlertsOut – structure of alerts including any alerts raised during execution of
function
EstimateSOP reports the state of polarization (SOP) of the tributaries in the optical
signal. The result is provided in the form of an orthogonal (rotation) matrix RotM.
For a polarization multiplexed signal the
fi rst column of RotM is the SOP of the
fi rst tributary, and the second column the SOP of the second tributary. For a single
tributary signal, the fi rst column is the SOP of the tributary, and the second column
is orthogonal to it. The signal is transformed into its basis set (the tributaries
horizontal vertical polarizations) by multiplying by the inverse of RotM.
100 OM4000D Series Coherent Lightwave Signal Analyzer