App-23
IM AQ6376-01EN
Appendix
1
2
3
4
5
6
7
8
9
10
11
App
Index
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.
Automatic Parameter Setting Function
This unit provides the noise area/mask area automatic setting function. To activate the
automatic setting, set the algorithm to AUTO-FIX or AUTO-CTR.
AUTO-FIX
Noise Algorithm
Obtain the left and right noise areas (NA_Ri, NA_Li) of each channel according to the
number of detected WDM channels as follows:
When the number of WDM channels “n” is 1
Internally obtain the measurement resolution of SNi calculation trace and the value of
the noise measurement point NOISE AREA in accordance with the resolution, and then
obtain the values from the following equations.
NA_Ri =
λ
i + NOISE AREA
NA_Li =
λ
i - NOISE AREA
When the number of WDM channels “n” is 2 or more
Obtain the channel spacing of each channel (spacing of
λ
i.) With the minimum spacing
set to SPACING as well as NOISE AREA = SPACING / 2, obtain the NOISE AREA.
Finally, obtain the values from the following equations.
NA_Ri =
λ
i + NOISE AREA ( i =1,2,…,n )
NA_Li =
λ
i - NOISE AREA ( i =1,2,…,n )
Fitting Algorithm
While the setting is at AUTO-FIX, LINEAR is used for the fitting algorithm, which is
calculated as follows.
• Obtain ELi and ERi as the level (LOG) of each position of the noise areas NA_Li and
NA_Ri.
• Use the data of the straight line connecting the two points of ELi and ERi to fill the
inside of the fitting range.
• Set the level of
λ
i of the data generated in the fitting to the noise level LNi.
Note
Due to being set to LINEAR, it is not possible to set the mask areas.
AUTO-CTR
Noise Algorithm
Obtain the left and right noise areas (NA_Ri, NA_Li) of each channel according to the
number of detected WDM channels as follows (while treating the center points between
channels as NA_Ri and NA_Li).
When the number of WDM channels “n” is 1
Internally obtain the measurement resolution of SNi calculation trace and the value of
the noise measurement point NOISE AREA in accordance with the resolution, and then
obtain the values from the following equations.
NA_Ri =
λ
i + NOISE AREA
NA_Li =
λ
i - NOISE AREA
Appendix 4 Detailed Explanations of WDM Analysis Function