Tektronix OM4006D, User Manual

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Core Processing function reference
R.A. Grif fi n, A.C. Carter, "Optical differential quadrature phase-shift key
(oDQPSK) for high capacity optical transmission," OFC 2002 conference,
Anaheim, US, paper WX6, 2002.
EstimateClock
function [Clock,BoundValsOut,AlertsOut] =
EstimateClock(V,ChDelay,pHyb,FreqWindow,NonlinFunc,BoundValsIn,AlertsIn)
V – 1x4 array of structures, each containing waveform (voltage values) from scope
ChDelay – 4-element vector of time delays between scope channels, usually
obtained by separate calibration
pHyb – 2x4 array (4 column vectors) containing characteristic Jones vectors of
optical hybrid ports, usually obtained by separate calibration
FreqWindow – range of frequency in which symbol clock frequency may be
located
.Low – low frequency limit
.High – high frequency limit
NonlinFunc – string containing instruction for nonlinear function used in clock
recovery
BoundValsIn – structure of boundary values from previous block AlertsIn –
structure of alerts accumulated before executing function
Clock – structure containing estimated symbol clock:
.t0 – time of fi rst symbol center after t = 0
.dt – symbol period
BoundValsOut – structure of boundary values to be passed to next block
AlertsOut – structure of alerts including any alerts raised during execution of
function
EstimateClock determines the symbol clock frequency of a digital data-carrying
optical signal based on oscilloscope waveform records. The scope sampling rate
may be arbitrary (having no integer relationship) compared to the symbol rate.
The clock recovery process has three steps:
OM4000D Series Coherent Lightwave Signal Analyzer 97