YASKAWA AQ6370B - Page 319

App-7
IM 735302-01E
Appendix
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App
Index
RMS Method
Use the RMS method to obtain the spectrum width and its center wavelength.
Following table shows the details of parameters for the 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 threshold value TH, within the displayed
waveform, and find the spectrum width by the following calculation.
• WhenthewavelengthatbeachpointisλiandthelevelatthepointisPi,themean
wavelength
λ
c can be found by the following expression.
λc =
∑
λi
Pi x
∑
Pi
• By using the mean wavelength
λ
c, find the spectrum width
Δλ
by the following
expression.
∆λ =
∑
(λi - λc)
Pi x
∑
Pi
2
Appendix 2 Data Calculation Algorithms for Spectrum Widths