Agilent Technologies 86038B, Руководство пользователя

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Agilent 86038B Photonic Dispersion and Loss Analyzer, Second Edition
Diagnosing a phase wrapping error is not always easy, because
the extent to which phase wrapping affects the shape of the
measured relative group delay curve depends upon the details
of both the test device and the measurement setup parameters.
Be conservative in the use of
Equation 6 , as it is possible for
phase wrapping errors to go entirely unnoticed. In addition to
the display of maximum CD in the Sens/Res setup panel, Agilent
provides a similar calculation in an Excel spreadsheet
calculator for estimating the maximum allowable step size. It is
called the Wavelength Step Calculator for Modulation Phase
Shift CD Measurements and can be found in the Library section
of the public Agilent product web page for the 86038B.
Maximum RF Modulation Frequency (MHZ)
The following table lists recommended modulation frequencies.
Any modulation smaller than that listed will give correct results
(that is, no phase wrapping). Smaller modulation frequencies
will have more noise and better resolution. Table cells that have
an arrow symbol (
ℜ
) indicate that you must decrease the
wavelength increment to achieve the desired
∆τ
RGD.
Table 2-1. Maximum RF Modulation Frequency (MHz) for <90° phase steps
f
90
=
∆λ
Wavelength Increment (nm)
∆τ
RGD
(ns/nm)
0.001 0.005 0.01 0.05 0.1 0.5 1 5
0.1 any any any any any any 2500 500
0.5 any any any any any 1000 500 100
1 any any any any 2500 500 250 50
5 any any any 1000 500 100 50 10
10 any any 2500 500 250 50 25 5
50 any
1000 500 100 50 10 5 $
100 2500 500 250 50 25 5 $ $
500 500
100 50 10 5
ℜ
$ $
1000 250 50 25 5 $ $ $ $
5000 50
10 5 $ $ $ $ $
10000 25 5 $ $ $ $ $ $
50000 5
$ $ $ $ $ $ $
f
90
1 4 Δτ Δλ × × ( ) ⁄
=