App-9
IM AQ6370D-01EN
Appendix
App
Appendix 2 Data Calculation Algorithms for Spectrum Widths
NOTCH Width Measurement
Obtain a bottom level. Then, obtain the NOTCH width for the bottom level and its center
wavelength.
Following table shows the details of parameters for NOTCH analyses.
Parameter Abbreviation Default Value Setting Range Unit Description
THRESH TH 3.00 0.01 to 50.00 dB Threshold value
K K 1.00 1.00 to 10.00 - Multiplying factor
TYPE TYPE BOTTOM BOTTOM / PEAK - Reference position for
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Algorithms for analyses are described here. They differ depending on the types of
analysis (BOTTOM/PEAK). Algorithms for each type of analysis are described below.
When “TYPE” is BOTTOM
λmin
LGmin+TH
LGmin
• Obtain the minimum level “LGmin.” Also, set the wavelength of this point to λmin.
• Set the rightmost wavelength, which is located on the left of λmin and which crosses
the level (LOG) of |LGmin + threshold value (THRESH[dB])|, to λA.
• Set the leftmost wavelength, which is located on the right of λmin and which crosses
the level (LOG) of |LGmin + threshold value (THRESH[dB])|, to λB.
• Obtain λA and λB through multiplication by the value which is set to the multiplying
factor K.
λ'C = (λB + λA)/2
λA = K × (λA − λ'C) + λ'C
λB = K × (λB − λ'C) + λ'C
• Obtain the NOTCH width from the following equation.
Δλ = λA − λB
• Obtain the center wavelength λC from the following equation.
λC = (λA + λB)/2
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