App-8
IM AQ6376-01EN
PEAK RMS Method
Use the PEAK RMS method to obtain the spectrum width and its center wavelength.
Following table shows the details of the parameters for the PEAK RMS method.
Parameter Abbreviation
Default Value Setting Range Unit Description
THRESH
TH
20.00
0.01 to 50.00
dB
Threshold value
K
K
2.00
1.00 to 10.00
-
Multiplying factor
Algorithms for the analysis are described below.
Peak Level
Threshold
Value
• Take out the data points exceeding the limit value TH, within the displayed waveform,
and find the spectrum width by the following calculation.
The mode peak count above the TH is shown in the MODE data area.
• When the wavelength at beach point is
λ
i and the level at the point is Pi, the mean
wavelength
λ
c can be found by the following expression.
λ
c =
∑
λ
i
Pi x
∑
Pi
• By using the mean wavelength
λ
c obtained in above discription, find the spectrum
width
Δλ
by the following expression.
Δλ
=
∑
(
λ
i -
λ
c
)
Pi x
∑
Pi
2
K x
Appendix 2 Data Calculation Algorithms for Spectrum Widths