Tektronix OM4006D, Руководство пользователя

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Appendix E: Equivalent-Time (ET) oscilloscope operation
While the modulating frequency, f
n
is still the same, the frequency deviation, f
D
,
has been reduced by 2 π f
n
∆ t where ∆ t is the time difference for the two paths.
Some lasers can have frequency deviations in the 200 MHz range over 1 ms. To
minimize the FM bandwidth after detection, reduce the frequency deviation to ~
1 kHz. This is accomplished with
∆ t = 0.8 ns or a path difference of 16 cm or less.
Generally speaking, the ET measurement performance is best with a path
difference less than 10 cm when possible. For lower noise lasers, path lengths
differences up to 2 m can be tolerated.
Matlab Engine fi le (ET)
You can con fi gure MATLAB to perform a wide range of mathematical operations
on the raw or processed data using the Engine window. Normally the only call
is to CoreProcessingCommands, the set of routines performing phase and clock
recovery.
NOTE. To view a complete list of variables, open the MATLAB Command Window
and enter who .
NOTE. CoreProcessingCommands will provide either ET or RT processing
depending on which mode the OUI is in. To ensure you only get ET processing you
can use CoreProcessingET in the window instead of CoreProcessingCommands.
Similarly you can use CoreProcessing in the Engine Window if you want to be
sure you only get real-time processed data.
OM4000D Series Coherent Lightwave Signal Analyzer 141