Anritsu MS9740B - Setting Items; Calculation Method

5.3 Measuring LED (Light Emitting Diode)
5-11
5
Measurement Functions
5.3.1 Setting Items
This function has following setting items.
● Cut Level
This sets the threshold level used to calculate Mean Wl (n dB), ndB
Width, and PkDens (/1nm).
When calculating Mean Wl (FWHM), FWHM (2.35 σ), Total Power, and
σ, all data are used irrespective of Cut Level.
● Power Cal
This is the calibration factor used at Total Power calculation.
● Kσ
This is the constant for the standard deviation σ.
5.3.2 Calculation Method
The following equation is used to calculate the level L
1
, L
2
, L
3
---L
n
for all
measured wavelengths
l
1
,
l
2
,
l
3
---
l
n
in the spectrum. Here the peak
wavelength is bigger than the level lowered the level at Slice Level from
the peak of the measurement spectrum.
● Mean Wl (ndB)
2
ba
c
ll
l
+
=
l
a
,
l
b
(
l
a
<
l
b
) are the wavelengths for the levels at the Cut level below the
peak.
Figure 5.3.2-1 Definition of
l
a, and
l
b
● Mean WL (FWHM)
∑
∑
⋅
=
n
nn
c
L
L
l
l
● ndB Width
ab
lll −=∆
● FWHM (2.35 σ)
2
2
35.235.2
c
n
nn
L
L
l
l
σl −
⋅
==∆
∑
∑
l
a
l
b
Cut Level