App-21
IM 735302-01E
Appendix
Algorithm for Analysis
mask
area
llevel
Fitting Line
noise
area
wavelength
Data range for use in the fitting calculation
Measured noise level
1. Apply channel detection to measured waveform data using the following procedure:
• Find all maximum points and minimum points to obtain mode peaks where peak/
bottom differences between maximum points and minimum points on both sides
are equal to or greater than MODE DIFF.
• Of the obtained mode peaks, choose only the ones whose level difference
compared to the highest peak is equal to or greater than THRESH. Note, however,
that mode peaks with a level difference equal to or less than DISPLAY MASK
shall be excluded. The number of mode peaks chosen in this manner shall be the
Number of Channels “N.”
2. Obtain the wavelength
λ
’i of each mode peak.
3. Obtain the level LPi of each mode peak.
4. Obtain the center wavelength
λ
i of each mode peak, which is the center of the two
points below the mode peak
λ
’i by A[dB] both on the left and on the right. (A[dB] shall
be either 3 dB or the setting value of MODE DIFF, whichever is smaller. )
5. Follow the setting of the parameter NOISE ALGO to determine the noise area and
mask area for performing the NOISE fitting.
(If the mask area is set outside the noise area when the channel wavelength
λ
i is the
center, the mask area and the noise area will become the same value.)
6. Obtain the measurement resolution RBi of each channel from the values stored in the
AQ6370B.
7. According to the setting of the parameter FITTING ALGO, generate fitting waveforms
from the noise area and mask area determined in 5 and obtain the level at the center
wavelength
λ
i as the noise level Lni.
8. Use the peak level LPi and the noise level LNi obtained in 3 and 7 to obtain the level
Li of each channel from the following equation.
Li = LPi(linear) - LNi(linear)
9. Obtain the normalized noise level LNNi from the equation below.
LNNi = [LNi(LOG) - 10×Log(RBi[nm])] + 10×Log(NBW)
NBW =noise bandwidth (configurable parameter)
10. Use the mode peak level Li obtained in 8 and 9 and the normalized noise level LNNi
to obtain SNi from the following equation.
SNi = Li - LNNi
11. Display the results of foregoing analyses according to the settings of the parameter
DISPLAY SETTING.
Appendix 4 Details of WDM Analysis Function
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